I I I I I June, .J 1969 I

•

- . - - . ·-- --· ------··-·-·--·-·····--··-· ----·---· · ··-·· ·-·--·-- ···-- . ------··------[ - ! San Fernando Valle,y State College

i jI

I EFFECTS OF TROPICAL CYCLONES UPON SOUTHERN CALIFORNIA jI I \i I I A thesis submitted in partial satisfaction of the requirements for the degree of Master of Arts in

i Climatology I by

I �dchael Ford Harris

Ii I I I I June, .j 1969 I

I I

I I Ii - - · - ______···------·------·--·- .. . ----.. -· ...... - - · . [ ______-·------· - . . - . . _ ... - -- . .. ,_ ...... I ......

· The thesis of �cha.el Fqrd Harri� is approved:

Co:rmidtt.ee Chairm.a.n

San Fernando Valley State College

June 1969 TABLE OF CONTENTS

PAGE

List of Tables •••••••••••••••••••••••••••••••••••••••••••••• v

List of Figures ...... vi

Acknowledgments ...... vii

Abstract ...... viii

CHAPTER

I. INTRODUCTION ...... 1

1.1 Tropical Qyclone Importance 2

1. 2 Definitions ...... 6

PART I: BACKGROUND

II . LITE!l.A.TURE REVIEVJ' ••••••••••••••••••••••••••••••••••••• 9

2.1 Growing Recognition ...... 9

2.2 nsonoran Storm.s •••.••••••••••••••.••••••.••••.•• 13

! III. CHARACTERISTICS OF EASTERN NORTH PACIFIC

TROPJ:,CAL CYCWNES ••••••••••••••••••••••••••••••••••••• 16

I J.l Tropical G,yclone Frequenc,y •••••••••••••••••••••• 16

3.2 Tropical G,yclone Origin Areas ...... 19

3·l Tropical G,yclone Movement ••••••••••••••••••••••• 23

3.4 Tropical G,yclone Intensity •••••••••••••••••••••• 27

TROPICAL CYCLONE ACTIVITY PRIOR TO 1961 ...... 30 IV. 4.1 Tropical G,yclone Activity in

Southern California .••••••••.•••••••.••••.•••... 30

Tropical Qyclone Activity in Baja

California and the l1exican Mainland ...... 33

iii CHAP.rER

II: PRECIPITATION P.ll.RT

METHODS AND TECHNIQUES ...... v. 5.1 Need for Subjective � sis 36 y

5.2 Precipitation Station Network ...... 37

5.3 Precipitation Identification ...... 42

5.4 Supplemental Techniques ...... 44

5.5 Statistical Methods ...... 46

DISCUSSION •••••..••.•••.•.••.••••••.•••..•.••••••••••• 51 VI.

6.1 The Seven Storms ...... 51 .

6.2 Areal Distribution ...... 54

SUMMARY CONCLUSIONS ...... VII. AND

BIBLIOORAPHY ...... 65

APPENDIX A ...... 73

APPEl'l'DIX B • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • 77

II IlI

II �•-••·•- --v---·••---·------·----•••----•·••-• L.. ••••••-·-··•-·•-·•�·�-·••-·-·-·-·------·---·--.-·-- ••-·----•••-•·-----·--·---••••-

iv LIST OF T.ABLES

T.ABLE PAGE

Beaufort Wind Scale ...... 8

2. Monthly and Annual Tropical Qyc1one Frequencies

as Presented by Various Authors ••••••••••••••••••••••• 17

3. Hurricanes and Tropical C,yc1ones, 1961-1968 ••••••••••• 19

4. Hurricane Frequency ...... 28

5. Precipitation Stations Per Elevation Intervals • • • • • • • • 38

6. Precipitation Stations Used in T'nis Study • • • • • • • • • • • • • 39

7. Tropical C,yc1one Precipitation, Annual Precipitation, and Tropical C,yclone Precipitation as a Percentage of

the Annual Precipitation •••••••••••••••••••••••••••••• 47

8. Total Annual Precipitation, Total Tropical C,yc1one Precipitation, and Tropical Qyclone Precipitation

Percentages ••••••••.•••.•••••••.••••••.•••••.••••.•••. 49

9. at Six Desert Stations, 1961-1967 •••••••••••• 61 Rainfall

v LIST OF FIGURES

FIGURE PAGE

1. The Eastern North Pacific Tropical Cyclone

Activity Region...... • ...... • ...... 3

2. Principal Shipping Routes Through the Ea stern North Pac:i.fic...... 5

3. P�rcentage of Tropical CIJclone Origins Per ·

5 Squai:'es. • . . • • • . • . . • • • • • . . . • . . . • • . • . . • • . . . . . • • • • • .. . 21

4. Mean Summer Sea Surface Temperatures...... 22

5. Percentage of Tropical Cyclone Occurrence Per Squares, 1961-1968...... 23 5° 6. Hean uly �ftugust Positions of the Eastern J and North Pacific Wind Shear Line...... 25

7. Storm Duration in Days, 1961-1968...... 27

8. Hurricane Wind Speeds, 1961-1968...... 29 �aximum 9. Precipitation Station Network Used in this Stuqy...... 41

10. Potential Zone and Potentially Effective Storms.• • • • • • • 43

Total Precipitation .Associated with the Seven 11. Tropical C,yclones from 1961 to 1967...... 56

12. Mean of .Annual Percentages, Seven Years, (Ya)...... 57

13. Mean of .Annual Percentages, Six Years, (Yb) • • • • • • • • • • • • 58 14. Percentages of Total Precipitation (Seven Years) Associated with Tropical G,yclones, (Yc)...... 59 15. Percentages oi' Total Precipitation (Six Years) Associated with Tropical C,yclones, (Y )...... d 60

...... ------L______--�------______vi ... ·�- -�-----· ------. ---- - ��--·--- --� ------�-----·------Ii

ACKNOWLEDGMENTS

This thesis is an outgrmrth of a paper prepared during a course

hydrometeorology at San Fernando Valley State College. The extent in

of the paper and its findings indicated that further study of the

subject was necessary. In completiJ."'lg the present work, the author

has come to better understand the problems 1dthin the fields of

meteorology and climatology.

the course of this study, assistance was offered by During many

and grate.fully accepted. My sincere appreciation is extended to my

thesis committee, • .Arnold Court, David A. Henderson, and Dr Dr. Dr.

Peter F. Mason. I express deepest thanks to Court for his my Dr.

untold hours of encouragement and unending patience. Acknov;rledgment

is given to Robert DeViolini, Duane Lea, and Jay Mr. lf.i!'. Mr.

Rosenthal of the A·�ospheric Science Section at Point Mugu Vdssile

Center for their satellite photographs and advice; and to George l1r.

Kalstrom and his associates at the Los Angeles Weather Bureau Office

for unlimited use of their files. Personal thanks is addressed to my

typists, Shelly Lorraine, and also to James A. Roberts for and Dr.

his moral support.

To "Little One", without whose love, patience, and occasional rey

kicks to derriere this work would never have begun, I lovingly my I'II dedicate this thesis.

______------·-·------· ------·-·------lL ----·- ·--··· ---· --·· ····-·- -- - ·-·- --·-··---·-·- vii .ABSTRACT

EFFECTS OF TROPICAL CYCLONES UPON SOUTHERN CALIFOR�ITA

Michael Ford Harris

Master of .Arts in Climatology_

June, 1969

The effects of tropical cyclone rainfall upon the late summer

and early autumn precipitation regimes in ;'Southern California have

been investigated.

Eastern North Pacific tropical cyclones occur on an average of

11 per year, with about one pe r year producil"'.g noticeable effects in

Southern California. Effects, other than increased out-of-season

p�ecipitation, are evidenced by damages in excess of $25 million to

both agricultural and non-agricultural activities.

Rainfall associated with these storms accounted for sir;nificant

percentages of the annual precipitation at most of the Southern

California stations exai'llined. At many stations 10 percent to 15

percent of the annual total precipitation was attributed to this

activity, while amounts in excess of percent were noted 20 at,

several desert stations in southeastern California. Tropical cyclone

precipitation also accounted for 40 percent to 70 percent of the 1

seasonal--June through October--precipitation at these same l stations.

I I

l.-·---·· ·------·-- -· ---

- - - viii CHAPTER I

INTRODUCTION

Hurricanes and their lesser counterparts, tropical storms, form

:a considerable portion of the atmospheric system. Landsberg (1960) i i 1strongly felt that hurricanes played a major role in the general

circulation by dissipating large amounts of energy in condensing water

vapor. Not only do the tropical cyclones produce precipitation �dthin .

their area of existence, but they also transport moisture from the 1 ' low latitudes to the high latitudes. and Miller stated Dunn (1964)

,that, without the hurricane, precipitation over the Great Plains

!would be greatly reduced, while Rosendal (1962) stressed the fact 1 i that the benefit of attendant rains frequently outiveighs the

destructive forces of the stonns.

The precipitation attendir� tropical cyclones has seldom been

studied as a factor in the climatology of an area. Only Cry (1967)

has dealt with this problem, for the East Coast of the United States.

The thesis here presented offers an analysis of the effect. of eastern

North Pacific hurricanes and tropical storms upon the Southern

California area.

The effects of these tropical cyclones will be shown in detailed

accounts of individual storms. Their significance will be measured by

the percentage of total annual precipitation that is associated with

tropical cyclones.

1 2

1.1 Tropical 9yclone nnportance

1), The eastern North Pacific ( Figure although mentioned in early writings as an area of tropical cyclone occurrence Redfield, 1857), ( has not received as much attention as has been devoted to other areas of cyclonic activity, especially the western North Atlantic and the western North Pacific. Both regions are easily accessible and usually

:have .frequent and vigorous tropical cyclonic activity. Less study has been given to other zones of tropical cyclone activity throughout the world, of which the eastern North Pacific is one.

Tne eastern North Pacific Ocean is an area of considerable tropical cyclonic activity. Tropical storms and hurricanes occUFring in this region affect not only the shipping routes from Panama to

Hawaii and the Far East, but also the west coast of North America.

The Mexican west coast is heavily affected by these storms, while occasionally tropical cyclones advance northward to be felt in portions of Southern California and the Southwestern Urdted States.

The importance of the eastern North Pacific zone has grown with the increase in shipping and economic development along the North

American west coast. The tropical storms and hurricanes occurriP� in the area have more potential destructive power now, simply because of the increased value of the region. Thus, it is very important to understand the characteristics of tropical cyclones and their effects upon this part of the 1-rorld.

Tropical cyclones rarely inflict full storm effects in Southern

California. Often, however, Baja California is raked by storms of

1962). hurricane intensity (Rosendal, Loss of life and several ...... ··-········-· ·· ···· ··--·-···-- ··· ------...... ··· ··-- ···--· ·· ··----····--·--· ·-· ---.··· r------,

1000 O o lb5° 9-r: 9-o I

.•. >.�·; •

. ·,

"'-- - . \ --...... ' L ,..- '"

' ' GuadaluJPe f "'... • v-- ' Island 1 Point San ' Eugenio

.evillagiged� Islands • 0 • •

0Clipperton1Island

0 o .. 0 0 0 125 120° ... 0 ios 0 "'0 ll 0 91"' 9

Figure 1. The eastern North Pacific tropical cyclone activity region. L.__,_I ------

\.4.) 4

millions of dollars in damages have resulted from these tropical

cyclones. The effect of these storms on Southern California is usually

1932). increased out-of-season precipitation (Reed, This activity,

although often quite welcome to the parched South:tvest, may be of destructive force. The fruit drying industry is most v.aturally

affected if the precipitation is intense. The mere presence of clouds,

usually attending tropical air masses, may affect the ripening of

vine crops in such a w� as to decrease or obliterate the crop yield

1933). (Blake, Massive topographic changes, caused by flash flooding, are also evidenced.

Tnunderstorm activity is characteristic of the desert regions of

California and Arizona and occurs in w-1arm, moist tropical air brought

into the area from the Gulf of Hexico and from the eastern North

Pacific. Intensification of the thundershower precipitation produced

1by the presence of a tropical cyclone is the primary cause of crop and land damage. The effects of the northward movement of tropical

cyclones, quite understandably, are not as dominant in Southern

California as those of other weather features in the yearly cycle.

But occUF�ing in the off season--late summer or early autumn--this precipitation may have a definite economic and geomorphologic consequences.

The eastern North Pacific is an area in which meteorological phenomena are not readily observable. Prior to 1961, weather observations, particularly tropical cyclone detection and tracking, were determined by ship reports. These were usually restricted to the

shipping lanes bordered by the seaw�s from Panama to the United 5

States west coast and from Par�a to Hawaii and the Far East

Figure 2) . Since 1961, when the first Tiros weather satellite ( w·as placed in orbit, weather detection over the area has increased

considerably. These observation platforms have tremendously

increased the number of tropical cyclones reported.

Because of this improved tropical cyclone detection, this stuqy

is restricted to the tropical cyclone season--Nay to Nove...-riber--of the

years 1961 to 1967. Included in the discussions of Chapter III,

11Characteristics of Eastern North Pacific Tropical Cyclones11, are

hurricane and tropical storm data for the 1968 season. However,

precipitation data for 1968 were not yet available for the

tabulation of tropical cyclone effects •

-1 �...... : ..... : ...... �' tr\:4.:-'-F-::::..'.1;_-__,.,r-=:-t-!_-t,..._...... ,.�l�"'�""�i . · · · . · . . : ...... : ..-?� · : _ .. . . : . .. 1...:-q � . . \. . :. _:...... : ...:: : ...... : : _.: ...... _: . ...' 1�\'\. ,_, · . :·. .. _ _ · a I I � · : _.: : :: _.: .- : _.: i · : : ; . _ _ .. o."!<::l_ ... : . : : ... . ·��" I � �-"-·· : : -.·: -.::·:- \IJ'est ·• -- ·· ·· I • ro-- . / '-1 / • ' • . ' • . . ' • • t-- j · • • . ' ."' "· _ : _ . . C· rcl Ro" te / : //:: : _ -�_ � ...:...:...:: .. : ·· .. : ···- //_ : �:· �: L ::/.{'/// ///_//////_.: / ///.-_..-·////_ :: . / ::�-:: : :: .... �- / · ' ! Grebt . · ..;1-'-'- �: �:::,_.. ' : 1;.,"'::>�'"'- u � r . . . . ' .· . . . ·: . :;. ,...,. , ,...... -!' ' .l:'anFIJna-J awa: �-Ii'G'!I' .!!;.= : st • . """"'•··r---:.:.: !-..._ . -�· ' ... . . ,_ • :.:· :"::·.-:-. . '· · I --·1-_ _ : · . . � -.'r-lJ�.·..:_:_�-)"'1 ! '. r . :.... )----;/ -· ·; jor shipping areP. I ....:..: .. -:.:::_.. f'I,, o• o• \00° J ' •

Figure 2. Principal shipping routes through the eastern North Pacific. Sadler, 1964). ( 6

1.2 Definitions

Tne terms and their definitions cited in this study are those

derived from the Smithsor.ian Heteorological Tables (Smithsonian

19.58) , • Institution, and the �'leather Bureau Operations Hanual (U. S 1968) . . Department of Commerce, These terms and definitions are

:generally accepted by most authors and agencies, but differ slightly

from those found in the Gloss�; of Meteorology ��erican : ( ! ·Meteorological Society, 19.59) .

Cyclones are atmospheric systems in which the barometric pressure

decreases to a minimum at the center. Wlnds spiral inward toward the

lm� pressure, causing rising air. Clouds and precipitation are

produced. The circulation is counterclockwise in the Northern

Hemisphere and clocb·rlse in the Southern Hemisphere. Tnese s,ystems

vary in extent, but usually cover at least 40 miles of approximately

circular area. T'.ae name "cyclone11 does not denote intensity, but is a

term utilized for all storms of the above description. These stonns

occur in both mid latitudes--extra-tropical cyclones--and low

1964) . latitudes--tropical cyclones--(Dunn ar� }filler,

A tropical cyclone is a nonfrontal cyclone of synoptic scale,

developing over tropical or sub-tropical waters and having a definite

organized circulation. The United States Weather Bureau distinguishes

:four stages of tropical cyclones, classified according to intensity:

(1) The weakest recognizable stage of a tropical cyclone is the

tropical disturbance, in which rotary circulation is slight or absent

at the surface, but possibly better developed aloft. There is either

, one closed surface isobar or none at all, and no strong winds. 7

(2) The weak stage of a tropical cyclone with a definite closed

surface circulation, one or more closed surface isobars, and the

: highest w·ind speeds less than 34 knots--39 mph--is a tropical

'deeression. (3) A tropical storrn is a tropical cyclone ,.lith closed

:isobars and maximum wind speeds of from 34 to 63 knots--39 to 73 mph.

A is a large revolving storm--tropical cyclone-- : (4) hurricane :originating over tropical or sub-tropical waters with winds of 64

knots--74 mph--or more blowing counterclocb?ise--in the Northern

He�sphere--around the center.

These wind speeds are based on the Beaufort Scale (Table 1). In this study, as in other works containing tropical cyclone

data, the term tropical cyclone, when utilized, will me�� only

.tropical cyclones which have reached tropical storm intensity--winds

greater than 33 knots. Thus, tropical cylones, v1ill include both : and only the last two classifications, tropical storm and hurricane.

In the next three chapters the frequency, area of origin, tracks,

intensity, and effects on the coast of eastern North Pacific tropical

cyclones are discussed. The final three chapters discuss the

:significance of tropical cyclone precipitation upon Southern ! : California. 8

----· ------· - -- ·· ------. .. """"···------· . -. I. BeaufOrt 1V:Lnd Scale TABLE 1958) ( from Smithsonian Institution,

J.V.d.les Specifications Description

:J.i'orce per hour Knots for use on land of >-lind

0 Calm, smoke rises ver-'c,ically...... Calm

1 1-3 1-3 Direction of vdnd sh��n by smoke drift, but not Light

by v1ind vanes . • • . • • • • . • • • . . • ••••air

2 4-7 4-6 Wind felt on face> leaves rustle; ordinary vane Light

moved by idnd .••••..••••••••••••breeze

3 8-12 7-10 Leaves and small twigs in constant motion,; wind Gentle

extends light flag •.••••••••••••breeze

4 13-18 11-16 Raises dust and loose paper; Moderate

small branches are moved .•••••••breeze

5 19-24 17-21 Sw�l trees in leaf begin to sway; crested wavelets Fresh

form on inland waters .••••••••••breeze

6 25-31 22-27 Large branches in motion; whistling heard in telegraph vdres; umbrellas used with Strong

difficulty ••••. •..•••..•.•••••••breeze

7 32-38 28-33 wbole trees in motion; inconvenience felt when Moderate;

walking against t-iind ••••••••••••gale

8 39-46 34-40 Breaks twigs of trees; Fl�esh

generally linpedes progress ••••••gale

9 47-54 41-47 Slight structural damage occurs ( chimney pots and Strong slate removed ) ••. •••••••••••••••gale 10 55-63 48-55 Seldom experienced inland; trees uprooted; considerable k�ole

structural damage occurs ••••••••gale

11 64-73 56-63 Very rarely experienced, accompanied by widespread

daraage...... •...... Storm

12 74� 64::£ ....•.••.•...... ••...•.•..•.HurricarJ.e PART I: BACKGROUND

CHAPTER II

LITERATURE REVIEli

Although the literature concerning tropical cyclones is quite

·extensive, such activity in the eastern North Pacific has not been

:emphasized. Typical of the lack of recognition is Helm's (1967)

'popular Hurricanes: �>leather at its 1-J'orst, which does not mention

tropical cyclonic activity along the Mexican west coast.

2.1 Gr01ving Recognition

Several -vrorks on California cli1nate, which might be eA.-pected to

discuss tropical cyclones and their effects, fail to do so. Felton's

( 1965) i·mrk concerning the climates of California co ntains no

statements >vhatsoever of the influences of any tropical factors on

the climate of Southern CaliforP�a. McAdie (1903), Carpenter (1913),

and Bailey (1966), did not denote the presence of tropical cyclonic

·influences in their studies of California's climatic conditions, but

mentioned, without discussion, 11Sonora11 storras--thunderstorms ! i occurring in the SouthvJest. Although these storms can be caused by : •tropical cyclones, they are not dependent upon them. Of the three, ionly Bailey mentioned Chubascos, which is a local name for showery

weather, sometimes caused by tropical cyclones. Thompson (1950) based

'his research on the 11rainy11 season of 1 October through 31 March,

·completely avoiding summer precipitation. Neither Conroy (1933) nor

9 10

Demarias (1965), both concerned with atmospheric dispersion and

,precipitation distribution over Southern California, mentioned the

influences of tropical cyclones in the area. Only .Aldrich and Meadows

(1966),in their work on the Southern California clim:ate, stated that

, the tropical cyclone lvas a definite factor in the SUirliiler vreather.

,Their presentation included general descriptions of the phenomena and

;pertinent infor.w�tion as to the effects and frequency of these storms.

Some general works discuss both the eastern North Pacific

cyclonic activity and the effects of tropical cyclones on Southern

California. Tannehill ( 1934) stated that tropical cyclones did occur

;in the eastern North Pacific, but he did not go further. Wenstrom (1942) mentioned the tropical cyclone activity of the area and

included reports of the September 19 9 tropical storm which crossed ! 3 'the United States coastline at Los Angeles. B,yers (1944) devoted

several pages to the discussion of Mexican west coast hurricanes.

Tannehill (1952), in a work concerning world weather, investigated both the occurrence and effects of the tropical cyclones within the eastern North Pacific. Garbell ( 1947), Palmer ( 1955), Trewartha

(1962), and Riehl (1965), expressed various ideas concerning the origin and effect of both tropical storms and hurricanes in the area under study. Gray ( 1968), in discussing the distribution of tropical cyclones over the world, presented recent data to emphasize the eastern North Pacific's position as an active area of tropical cyclone occurrence. The most extensive discussion in a work whose main theme is not tropical cyclones is in Meteorology for Mariners

(Great Britain Meteorological Office, 1967). Frequency, movement 11

and origin of tropical cyclones in the eastern North Pacific are thoroughly discussed.

Tropical cyclo c influences in Arizona and Sonora are a major ni topic of a few authors. Reed (1933) stated that much of the rain in the far Southwest was due to the passage of "hurricane air" up the west coast of Mexico and into the area. However, Turnage and Maller.y

(1941), .although stating that a high percentage of the rain in the Sonoran desert and Southwest region was produced by thunderstorms, did not elaborate on the possibility of tropical influences. Br.yson and Lowr.y (1955) stated that a one or two day peak in early summer precipitation in Arizona was induced when a tropical cyclone off the west coast of Mexico aligned itself with a deep long, upper trough extending southwest-northeast. The resultant now of air from the southwest over the warm Gulf of California brought precipitation to

Arizona, at the northeast end of this system. Previously Jurwitz

(1953) stated that air flow from the west coast of Mexico was a major factor in the summer thunderstorm precipitation of Arizona, accounting for 40% to 60% of Arizona's total annual precipitation. Ives (1949) stated that the occurrences of tropical cyclones over the Sonoran

Desert was the major cause of the variability in precipitation.

Several works have been primarily concerned with tropical activity off the west coast of Mexico. Visher (1925) presented the first major work in which areas of origin and frequency of Pacific tropical cyclones were extensively noted. Hurd (1929) further discussed these storms and presented the first classification of tropical cyclones of the Mexican coastal area, grouping them ------�------r according to storm tracks--discussed later in section 3.3. He also I l enumerated the characteristics of these storms and described several

which had affected the Southern California area. Blake (1933)

admitted that tropical cyclones caused only a small percentage of the

precipitation in Southern California, but that the storms were

widespread, damaging ripening and drying fruits. He noted

particularly the stations of Warner Springs and Cuymaca, where 12% to

18% of the annual precipitation was attributed to tropical cyclonic

activity. Blake (1935) further discussed several cyclones that had

influenced the Southwest, although not with hurricane forces. The

results were excessive out-of-season--late sunrrQer or early autumn--

rainfall, and abnormally high temperatures. Mountainous and desert

regions, where flash floods occurred, were shown to be heavily

affected. Ives (1952) discussed "Hurricanes on the West Coast of

Mexico" before the Pacific Science Congress in 1949, but the work is

not available and Ives says ( Ives, that it is now obsolete. Dr. 1969)

Five recent works concerning tropical cyclonic activity the in

eastern North Pacific, have been of particular assistance. Kalstrom

(1952) was primarily concerned with the wind speeds and movement

characteristics of the cyclonic systems, because of the extreme danger

to shipping and .fishing. The frequency of tropical cyclones the in

eastern North Pacific and their storm tracks were the main themes of

Rosendal's work, citing several instances which hurricanes (1962) in

caused damage along the Mexican coast. Sadler (1964) found that the

frequency of observed storms had increased through the use o.f

satellite photographs as tracking devices, These photographs were 13

·�····-····· ·------�·--·-··· -·-�------·-···- --·-----···· ·---�---·-······-·- ______····-· --··--·· --- .. .. - - - - � - ·- .______. - - - . - ---..... - - -. also used to estimate the wind strengths and pressure characteristics

I of the tropical systems. The most recent work, DeAngelis (1967), is

very intensive study of tropical cyclone activity from a. 1947 to 1966;. i storm frequency and particular storm descriptions are major aspects. I! Discussions of frequency have been the main theme of written

work on eastern North Pacific tropical cyclones. In the next chapter

the various estimates are compared. The climatological significance

of the attendant precipitation has not been ana�zed, and on only a

few occasions has precipitation or damage caused by tropical cyclonic

activity been of major concern. This study offers a discussion of

these aspects of eastern North Pacific hurricanes and tropical storms.

2.2 11Sonora11 Storms

Tropical cyclones have often been confused with "Sonora11 storms

as factors.in the late er and early fall precipitation of Southern summ

California. Several authors who neglected the effect of tropical

cyclonic activity in Southern California did mention nsonora11 storms

in connection with the out-of-season rainfall. "Sonora" storms were 1

identified by Bailey (1966) as thunderstorms caused by a

I southeastern .flow o.f air from the Gulf of California, and by Carpenter 1

as an overflow an Arizona southerly storm in the spring. (1913) :frOlll

McAdie (1903) .felt that the 11Sonoran storm had some effect upon San i, I Diego, but did not possess enough power to have major consequences. other authors, LYnch, 1931; Reed, 1937) stated that these 11! ( thunderstorms--11Sonoras11-- were a definite aspect of summer II j precipitation, while Taylor (1954) made a clear distinction between I .---·- ·------·--·-···------·------·-·-·--·-···--·-·--·------··------·· - ---·----·· ····-----· ···-········- - ·--· .. L ... ---- -· . - -·- . i:a "Sonora" and the effects caused by tropical cyclones off the Mexican i west coast. An Analysis of Rainfall in the Sonoran Desert and Adjacent / Terri tory Turnage and Mallery, 1941) mentions nothing of tropical [ storm effects( or even the occurrence of "Sonora" storms, but identifies

1summer precipitation as that occurring in thunderstorms, with no ! explanation of cause. ! I The most extensive work done on 11Sonoras11 is that by Dean Blake

who in his works on the eastern North Pacific and Pacific j(1923),Southwest, concerned himself on numerous occasions, with the phennomena I li that influence Southern California's summer and autumn precipitation /I i patterns. His aptly entitled article, Sonora Storms,emphatically ! !distinguishesI between "Sonora" storms and tropical cyclones. I j Originally a "Sonora" was any storm in the Southwest whose origin was 1i not clear, but Blake identified it as a summer_thunderstorm in the

\! mountains and deserts of Baja and Southern California. The season-- / i mid-June to mid-September--is almost concurrent with the tropical

! cyclone season, but the highest frequency occurs in July and August, I I I while September is the month of cyclonic activity. In the ji maximum area of maximum intensity, San Diego County, most of the precipitation ! . I falls on east-facing slopes above 2, 000 feet. A "Sonora" typically I I begins between 9:00 and 11:00 A.M., with wisps of clouds; 1 i thundershowers follow by or 2:00 P.M. I! Blake's arguments for1:00 a difference between "Sonora" storms and ' tropical cyclone influences were: a the "Sonora" is caused by !i ( ) i factors close at hand, namely the convection in the Mojave and i 1 Colorado Deserts; b many storms occur at the same time; and 1 ( ) �. ··------·-·------···------.------�--- L ··------· ------·--·------·-·------I .. ------15

( c) the storms have little horizontal movement, beginning and ending within a radius of a few miles. He thus felt that the 11Sonora11 should not be considered a northward extension of a tropical s.ystem, because they were isolated, and stated flatly that the tropical rains of the south--Baja California--were not related to the thunderstorms of the north--southern California.

Perr�ps Blake's distinction, while generally valid, should be modified, since tropical air from the south may aid 11Sonora11 storm development. 11Sonoras 11 may occur without any abnormal airmass activity from the south. But if one forms in tropical air introduced into Southern California by a distant tropical cyclone, its consequences are not those of a. 11Sonora" storm, but are tropical cyclone effects. While this may not make order out of confusion, the distinction between the two phenomena should be realized. -··-·-· ·-----�---�------�---·-·····-----·----····-···---·-··--··-----·------·------·----�·--····· --·- \i .. CHAPTER III - i

CHARACTERISTICS OF EASTERN NORTH PACIFIC TROPICAL CYCLONES

Any assessment of the effects of tropical cyclones on the climate !I of Southern California, particularly its rainfall, requires I!information on the nlli�ber, location, movement, intensity, and general I behavior of such storms. Included in the discussions of t:r�s chapter [ are tropical cyclone data for the 1968 season. However, the past year I i is not included in the analysis of tropical cyclone effects found in l !chapters VI, and VII, because the necess� precipitation data v, I 1wasI not available. i I 3. 1 Tropical Cyclone Frequency I 1 Tropical cyclone activity in the eastern North Pacific formerly Iiwas considered insignificant, but as observational competence I increased, especially through satellite coverage, its importance j i increased markedly. More than a century ago, Redfield (1857) ! I chronicled only 11 storms in 8 years. Visher (1925) listed 95

! tropical cyclones in 92 years, but in 45 of those years no storms j!I were reported. Kendrew, in the first three editions of his textbook,

!I did not mention tropical cyclones in the eastern North Pacific, but I lin the fifth edition (1961) gave an annual average of 1.7 for an I unspecified period. Average monthly and annual frequencies given by ! various authors (Table 2) show a general increase with time. !

--·-· ·······--·······- -·- ···-· ·····---·-· IL. .••.• --�. ·------· --·-----· ---· .••...• ------16 17

j TABLE 2. Monthly and Annual Tropical Cyclone Frequencies as Presented j by Various Authors

!Source May Oct Nov Years Jun Jul Aug Year i Sep visher 0.1 1 .1 (1925) 92 o.o 0.1 0.1 0.2 0.3 0.2 l ) Great Britain j Hydrographic ! Office (1938) 19 0.6 7 0.8 1.8 0.9 0.1 4. 9 ! 0.1 o. ! Tannehill (1949, \ 1952) and U.S. ! Heather Bureau i 0.0 0 1 (1959) 27 o. 1 0.6 0.6 0.9 1. 9 1.0 5. I Kalstrom (19 52) 5 0.2 1. 2 0.6 1.0 2.2 0.6 0.2 6.0 ! Krick (1954) 6. 0 I !I Riehl19 < 54, 1965) 10 5.7 i Palmer (1955) 8.0 I/ Petterssen (19 8) 30 0.1 0.2 0. 1.0 1. 1.0 0.1 5 i) 5 7 9 .7 ' Kendrew ( 1961) 0.1 0.3 0.3 0. 6 0.4 0.1 1. 7 !I o.o I Rosendal (19 62) 15 0. 1.2 1.5 0. 9 2.0 1.3 0.2 7.5 I 3 I I Donn (1965) 30 0.1 0.8 0.7 1.0 1. 9 1.0 1.0 6.5 I DeAngelis (1967) 18 0.2 1. 4 1. 6 ' 1 .6 2.6 1.3 0.2 8. 9

lI Gray (19 68) 10.0 I AVER.AGE OF .ABOVE 5. 7 i �I 'iI Previous studies were based entirely on ship reports and the I ! shipping routes severely limited the zones of ob servation. Even to� I some tropical cyclones each year are not recorded by ships because l1 iI these storms occur outside the frequent� traveled shipping lanes ! Figure 2). With increased surface and aerial reconnaissance, better I ( reporting by land stations, and the presence of weather satellites, i I

______------·------·- L ..______... _ ..____ -----�--�------· ---- 18

the frequency of observed storms has increased, and undoubtedly will continue to do so Rosendal, 1962; Sadler, 1964; DeAngelis, 1968). ( The latest technique, the use of weather satellites, is now essential in tropical cyclone detection, tracking, and prediction Baum, 1966; ( Gustafson, 1968).

From satellite pictures, Sadler (1964) estimated that 30 tropical cyclones might occur per year, far more than the present figure, though not completely unrealistic. During 1968, 19 tropical cyclones were reported. Gray (1968) using 25 year averages for the entire globe estimated that 10 tropical cyclones, about 16% of the global total of tropical cyclones occur annually in the eastern North Pacific, making it secpnd only to the typhoon region of the western Pacific as an area of tropical cyclone occurrence. The Northwest Atlantic- including the western Caribbean and the Gulf of Mexico--produces only seven storms per year, 11% of the global total, while the Northv;est

Pacific typhoon region produces 22 storms, 36% of the global total.

From 1961 through 1968, 93 tropical cyclones were reported

(Table 3) in the eastern North Pacific, east of 180° longitude and north of the equator--the region used, avowedly or tactily, by other investigators. All occurred from June to November, vdth none in

May, although Tannehill (1952), Roden (1958), Rosendal (1962), and

DeAngelis (1967) all considered the tropical cyclone season to begin in M�. The 1961-1968 average of 11.6 tropical cyclones per year is greater than the estimates Table 2) of any of the previous authors, ( except Sadler's (1964) upper limit of 30 as possible in one year. 19

.. ---·-· ______. ,_, ______�_ .... ··-···---·----· -··"' ------·· . ------·------·--� .. ___,._ ... -·------· . --·· ._......

TABLE 3. Hurricanes and Tropical Cyclones, 1961-1968 Jun Jul Aug Se:e... Oct Nov Total Year H TC H TC H TC H TC H TC H TC H TC 1961 1 1 0 4. 0 1 0 1 0 2 1 2 2 11 1962 1 1 0 1 0 2 0 3 1 1 0 0 2 8 1963 1 1 2 2 0 0 0 4 1 1 0 0 4 8 1964 0 0 1 3 0 2 0 1 0 0 0 0 1 6 1965 0 ·4 0 0 1 3 0 3 0 0 0 0 1 10 1966 1 1 0 0 4 4 2 6 0 2 0 0 7 13 1967 1 3 0 4 2 4 2 4 2 3 0 0 7 18 1968 0 1 0 4 3 8 2 3 1 3 0 0 6 19 TOTAL 5 12 3 18 10 24 6 25 5 12 1 2 30 93

AVG 0.6 1 .5 0.4 2.3 1.3 3.0 0.8 3.1 0.6 1.5 o. 1 0.3 3.8 11.6

H=Tropical cyclones which reached hurricane intensity ( �74 mph). TC=Total tropical cyclones (including hurricanes and tropical storms). (Mull, 1962; Benkman, 1963; Wilgus, 1964; McGurrin, 1965; Baum, 1966, 1967; Gustafson, 1968, 1969)

3.2 Tropical eyclone Origin .Areas

Eastern North Pacific tropical cyclones are generally considered to originate north of 10°N and west of 90°W (Hurd, 1929; Blake, 1935; Sadler, 1964). Alpert (1945) suggested that the air flow onto and off t�e coast of Central America was a possi�le cause of tropical cyclones in the Gulf of Tehuantepec (Figure 1). This area was described by Wenstrom (1942) as the region of greatest cyclonic generation. However, the Gulf has not been found by this study to be a pr:ilnary area of tropical cyclone origin.

Areas of origin, by 5° squares of latitude and longitude, as given by previous authors, and as found in the present study, are sho'lm in Figure 3. The numbers indicate the percentage of the total number of tropical cyclone origins which occurred within the square.

Squares in vihich at least 1 O% of the storms began are crosshatched,

squares of at least 5% are hatched. The similarities and differences between the maps indicate changes in the observational techniques and capabilities, and also variation in the mechanisms necessary for tropical cyclone birth.

The obvious agreement between Rosendal (1962) and Gr� (1968) arises from Gr�'s reliance on Rosendal for the Northeast Pacific.

In each of the five maps at least 90% of the tropical cyclones ° ° began between 90°W to 125 W and 10°N to 25 N. The areas with 10% or more of the origins show a general trend with time to the west betw·een ° ° ° ° 1 0°N and 15°N. The specific area of 15 N to 20 N and 100 W to 110 W, shaded on four of the five maps, is apparently the primary tropical cyclone origin area. This area has all three of the requirements

(Ramage, 1951) for tropical cyclone origin: vi arm water, warm air, and a source of low pressure. Sea surface temperatures average 86 F within the area (Figure 4; Sadler, 1964). .Average July air temperature; of 80 F (Tre".fartha, 1954) -vlithin the area produce the vertical air motion and instability necessary for storm development. Low pressure in the area is caused by low level tropical disturbances associated

------_,_. ------· - - ··- · ·------L.. _ -- -�--- � ------�------·------�- --·- ---· ------�------�------21

Visher I o' I I I I I o" I s• ., l 5" I�· r:f 'i" cf \ \( I�· [,.- )0 l.l n-·------· ····-·--·--·-·-----·--···----·-·--··-----·-· (1925) ··--·------'�--·-�··· --·t·------·------··1 ....- --- Storms 1832 - 1923 3.8 \.3 \ ."6 I 79 !.� �'H""- ..,_� I.'I 2.5 �.5 1.'3 '2. . \.'iJ \."5- • "l[ ...... ' 1'-.::�-...... ;;:. �...... � \.1 1 .'1 \ .1 5� 1 s• !5" 1 lr! t.d' I o• t!l" to" 1 s• t o• t s• 1 &' 1 6 1 ,_ -L'3 � \.'6 ----1 .

Rosendal 1 o• 1 1 s· 1 1• "00 1 s• q Iff' s· lr! cr I� q • \. � "'.

(1962) 0� ,.,. Storms """' 1947 - 1961 o., 112 � 't.S �� Z.7 �l:V<.)( )�� f.-. . �!-:l . �o.t:t o., \ .8 � � • " r;" s· I 1 s· t o" IS ·, o 1 s 1 o" I �� 'I � 10. ' \0 !i" tc!15' tel' � llx>' 'iSo "'P" .

DeAngelis I 'J0 I I do" 5' r:f

(1967 ) 0-" 1949Storms - 1966 160 0." o.f. 3. \

I o" ' I I I I rr I II I 6" I q '\ I 0 I 5' cf 'fS" 5" __..;....Ok !'>" 'j"' p� Po' cf Gray

Storms (1968Per) Years 25

I 6" I 1 s• 1 I 5' · • o" t o" 1 o' 1 I 'I • o" \J_1'f.: s• � ,� 1961 -1968 l.\ Storms ""' 93 '·' �l.l i\ . .\ �· \ '·' %.\ .t/. '5 ·�� • • \.1 . '"' 3.2 ��3.z. � Al.1 � 1 1 5° I 5" t t 5° t o• I I I S" I r;;• I 5° I 0° cf I �. , t:f 5" 0' ;oo�� • \ "1 ko 'I f 3. gure Percentage of Tropical Cyclone origins P 5° Squares .

-:;·I 22

- ······-- -.. ------··------·------·------·-·· - - --····· ·------··------·-· ···- ····-·--·····-··· ···· -- - r· ------(Durm ------, with old troughs (Sadler, 1964) and by easterly waves and !

• II Miller, 1964) Another mechanism producing low pressure is the i monsoonal trough or w nd shear line which marks the interface between I As west winds to the south and - east winds to the north. the I _/ Intertropical Convergence Zone--ITC--in the eastern North Pacific

I moves north during the su.mm.er, the shear line follows and becomes 111 positioned about 10°N during August, September, and October (Alpert, I 1946) . Interaction along this shear line can lead to cyclonic I development . !I I

' ' ' ' Sea Surface Temperatures I ...... ·I -- i . ' in Degrees Fahrenheit· ''-70--- ..... - I . """ .-"": ...... -- / /// I ---'2.06 ...... _ _7R...- ..... /�- -// -- --7+--- --

---.....__ . _ '// / ,.-- ' '(

Figure 4. Mean Surmner Sea Surface Temperatures (Sadler, 1964) .

k----,------· ····------·--·------·-··------I JI 23

3 . 3 Tropical Cyclone Iv1ovement

No "average storm track " can be established for tropical cyclones in the eastern North Pacific. However, all authors agree that most storms proceed to the north or northvrest, l·rhile remaining within several hundred miles of the coast . In Figure 5 the percentages of tropical cyclone occurrences per 5° squares of longitude and latitude are presented for the period from 1961 to 1968 . Squares with at least

5% of the tropical cyclone occurrences within their boundaries are crosshatched, those vrlth at least 3% are hatched.

Four types of tropical cyclones, classified according to track, were presented by Hurd (1929) : (1) "Coastwise storms 11 originate south of the Gulf of Tehuantepec, parallel the coast, and usually curve eastward onto the Mexican coast; (2) "Perpendicular to the coast storms 11 originate further south than the 11coasto;dse storms 11 and move farther west, a1'1ay from land; (3) "Revillagigedo Isla�ds storms " begin near the Islands--19°N, 111° tv to 112°'1'!- -and usually proceed west-v1ard;

(4) ·. t.Jestern storms occur west of 1250W and have no effect upon the

"' o s• 0 0 • 1 \ I o• rf: \ s• \ 0 c 1�5· 'o' \ C @.� �@Jj 2 , f: .:;::" /- "'<::> � . ...' �eo [.l 0 (}.� €.).(, Lb 2.7L. "'!! � l.tl o:a. 0 I � �'. fl>'((' .:0<1 . > u:o -· q,o \.lo ; N 0. 't. o.l 0.� O.l. @.� �PV

0 �� e.l o.l .,o so I 0 I \f'5o I l o· I, 5" I c• I I 1 o" I • 5. I f,o• l cf p;• o" 1 s• 5" I >a " �::f Figure 5 . Percentage of Tropical Oyclone Occurrence Per 5° Squares, 1961-1968 . 24

·�-- ···- . ------· ------·------· -·------·-· ·-----·-······------··· ------·-·------.. r .. ..-·- - ·· ------.. . -

North American coast, but can later regenerate and cross the central II:1 I i Pacific to become typhoons of the rTestern Pacific . 1 Of these four types, the first two--coastwise and perpendicular I to the coast--account for most of the storms during the period of I I study used in this paper. Several storms of type (4) caused considerable damag e i!l th.E! western Pacific . Hurricane Sarah, 19 67,

left the eastern Pacific id 1dnds of 65 knots, just barely th hurricane intensity, intensified aft er crossing the 180th meridian,

anc caused extreme damage to InTake Island with 13 0 kn.ot 1dnds . Hurricane Dot proceeded westward from 15 °N, 141°�4 causing 55 knot

1dnds, 30-40 foot seas, and approximately $6 million in damages to

the Hawaiian Islands in Aillf!.'Ust, 1959 (Stearns, 19 6o) .

I Presence of cool water west i'Tinds above 20,000 feet northwest I and Il of the area of origin of eastern North Pacific tropical cyclones I I presents a situation quite different from that in other tropical I � I) cyclone region of the world. Ocean water cooler than ab out 80 F (Figure 4) has a dissipating I effect on tropical cyclones as they move into mid-latitudes (Battan, 1I 19 61) . Blair (1965) stated that the boundar·.r for tropical 1 and Fite I cyclonic activity the eastern North Pacific v�as the 80 F isotherm, / in while Sadler (1964) maintained that i·l; merely marked the area of

I frequent dissipation. j The other cause of storm dissipation is a change viith height in wind direction west of 120'\1 (Gray, 1968) . Her upper westerlies, l,i1 air above about 20,000 feet, overlie the easterly trades of the lower I troposphere (Sadler, 19 64) as a result of the general circulation

•-·•·---·---··-•-•·-·-�·-·---·- -• "••w•-•-·-�·-·--··••---- ··-----·--�--�-·�-·----�-·-<- ··-· ---·-·•• -··••.. I..I --�------· .. �·-� •""-•--- ••·• --•··-- •- --• - "• 25

in the eastern North Pacific ( Sadler, 1969) . This wind shear is caused by the change of the north-south temperature gradient with altitude, and is characteristic of the tropics in general. Since the winds are a result of the thermal structure, the wind change will occur where difference in the thermal characteristics exist. In the i ' :e' astern North Pacific during sUlT'..mer, the thermal equator moves i :northward, increasing the temperature gradient between the surface and

!upper levels. Figure 6 shows the mean July and August positions of

:this wind shear. '

1\\"'\. - _..,. I ...... '� �,{" Jt:i::i v \ �i..f.· � vl±n ui::i " -�"'... SUR4'ACE Ea� t Wi nds '� �, , � ' '" j� st indc --" I � .....lliOFr : E< 1 - � ,,..,_ Ti' .!. T.T..! • \ .,.,., �� - _, ., =...... � ._..,� ..... · ,_.,..  .,.-'� � '\ I J r. , -- _ Mean Position f'"' .... f-- - July - - - I August c---

Figure 6. - Hean July and August Positions of the Eastern North

Pacific Wi nd Shear Line Sadler, 1964) • (

Another effect of these mechanisms is the srr�ll number of storms which cross the coast in or near Southern California. The only two such storms from 1961 to 1968 were Tropical Storm Katherine (1963), which crossed Baja California ab out 125 miles south of San Diego, and 26

Hurricane Katrina ( 1967), •fhich crossed the Gulf of California coast at the mouth of the Colorado River, 85 miles from El Centro, on her way to .Arizona . Rosendal (1962) presented the tracks of three tropical' ; cyclones which crossed the coast within 250 miles of San Diego in

September 1939. Such intense activity, however, has not occurred in recent years .

The whole personality of tropical cyclones within the area depends upon the strength and extent of both the cool water and the wind shear . The fectsef of these two forces are shown by the ab rupt decrease in tropical cyclone occurrences north of 25°N and west of

135'11 (Figure 5) .

Speed and duration of tropical cyclones are also heavily dependent up on the same forces, Eastern North Pacific tropical cyclones move at an average speed of 8 to 12 miles per hour Great ( Britain Meteorological Office, 1967) , varying with the month .

Kalstrom (1952) estimated the movement in nautical miles per d� as :

May-June July August September October-November Average 163 209 273 165 . 187 199

DeAngelis (1967) estimated the average speed at 7-12 knots, with a range from to knots . He also agreed Kalstrom that the 0 25 with rates of speed were lmvest in June and highest in August .

vfuile Kalstrom (1952) placed the average dur ation of storms at three days , ranging from one to · seven, Rosendal 1962) found the ( average duration to be four to five days, with a few storms lasting

10 days or more . For 1961 -1968, this study found the average storm length to be 5.9 d�s , with extremes of 1 to 15 (Figure 7) . 27

r------_------�

- I I

I 15 �b� I

of .s I --= I j Storms10 --= ! i I

1 2 3 4 5Days 6 of 7 Duration 8 9 10 11 12 13 14 15 I I S Figure torm Duration in Days , I 7. 1961 - 1968 .

Increase in storm duration may be explained by the increased II I ! area of surveillanc e by the satellites, permitting storms which would

not have been reported outside of the normal areas of ob s�ation, to ! .

be recorded and tracked.

Tropical gyc lone Intensitz 3 .4

Tropical cyclones of the eastern North Pacific are gener�

smaller and less intense than those in the Atlantic and in the

w7stern Pacific (Rosendal , Sadler placed the maximum 1962). (1964) intensity of winds in these storms near knots. Less than half 100 of the tropical cyclones reach hurricane intensity, winds of 64 knots or greater (Rosendal , Of the authors who se estimat es 1962). 13 2, ot trop�cal cyclone frequency are given in Table only three counted the storms which reached hurricane intensity . Their figures

of hurricane frequency and those derived· by this study are given in

I Table 4.

______l------I ------__)I1

- - 28

··------·····-······ · ····- --·-·····------····--·- · -· ··--····-·- -- ·---- -·--·-····------·--- --·- ·· ·

Table 4 . Hurricane Frequency

Period of Total Hurricanes Annual Averag e Source Study T.C. H. as % of TC Hurricane Frequency

Kalstrom ( 1952) 1947-1951 30 12 40.0% 2.4

Rosendal (1962) 1947-1961 112 48 42.8% 3.2

DeAngelis (1967) 1949 -1966 160 67 41 .9% 3 -7

This - Study 1961-1968 93 30 32.3% 3.8

Although the average numb er of hurricanes per year does not

change significantly from study to study, tropical storms can no�1

be detected mor e readily than a decade ago . The increase in observed

tropical cyclone occurrence causes the hurricane percentage to

decrease .

The western Atlantic has both a higher hurricane percentage and

annual frequency . From 1886 to 1956, hurricanes accounted for 58.3%

of the tropical cyclones, while averaging 4.6 occurrences per year

(Cry, Haggard, and White 1959). A slightly lower percentage, 55.5%,

and a higher frequency, 5.5 per year were shown for the same area

from 1931 to 1960 (Cry, 1967).

Although several eastern North Pacific hurricanes have produced

,winds of 100 knots or greater, the average maximum wind speeds

!ari e much less than those found in other areas . Rosendal (1962) set i i ithe maximum sustained wind at 100 to 125 knots, but DeAngelis (1967) ! !ni oted several hurri canes with winds in excess of 1 30 knots . '

A cumulative percentage graph of the maximum wind speeds of the i i \ 30 hurricanes which occurred between 1961 and 1968 is presented in

-�-•·------�----••-•-···- -•--·• - ·-·-· ---·· -•··-- •• -••• -·-········•·•-- •·· •· •V••-•· -----•-•••••�•------·•·•••••·· - L-.-�-i •·-·�-·�·-·-� -·�-.,•••-•-• -�•- ·--- · · •••· •· •-- • •-• 29

Figure In more than 50% of the hurricanes, vrinds were 75 8. maximum knots or less . Hurricane Sarah--8-22 September 1967--originated in the eastern North Pacific and developed vdnds of 130 knots west of the international date line, which therefore are not included in the maximum wind speed tabulation; the highest winds reported east of the date line, 65 knots, are included in the tabulation.

Total

Number

Hurricanes -c:--. '-'-zl.-.l.-ooh1o�-'l+r-15_-rlWindJ�J -"?!t-Speedcls--r in KnotsJ�o - ""J s::---lma l"'!"o- �l �o:s:'---"1-fJo

Figure • Max:imum Hurricane Wind Speeds, 8 1961 - 1968 . CHAPTER. IV

TROPICAL CYCLONE ACTIVITY PRIOR TO 1961

Many tropical cyclones have greatly affected Southern California

;a' nd Mexico in the past, and will continue to do so unless a method is ! 'derived to control these tremendous systems . Although Baja California 1! and the Mexican mainland are not the primary areas of concentrati on

/for this study, storms which heavily affected these areas will be irnenI tioned. Storms which affected Southern California between 1961 and i i [1967 will be discussed in a following chapter. I The present discussion ! will concern destruction, d&7lage, inconvenience and meteorological

!ei! ffects of storms prior to 1961 , and those afterward whose effects i ! did not extend north of the border . !

4.1 Tropical qyclone Activity in Southern Califorr�a

In Septemb er 1939, a tropical storm proceeded northward along the i !west coast of Mexico and curved inland at Los Angeles, the first i J !recorded tropical cyclone to have crossed the coast there. In this

!I destructive tropical storm on record in Los Angeles, 45 lives

lost at sea and $2 million in d��ag es were reported. So unique

was this storm that it is mentioned by many thors au concerned with

general topics, (Wenstrom, 1942 ; �J ers , 1944; Duru1 and Biller, 1964; 1967) .

The storm began on 14 September 1939 at about 10°N, 91�w and

the coast . The lowest barometric pressure was 910.9 mb--

30 31

28 .67 inches of mercury--reported on 22 Septemb er ab out 300 miles

:1�\'J of the tip of Baj a California . On 24 September, winds in its

quadrant were recorded at B?aufort force of to mil es NE 8 9--39-54

per hour . The next day , 25 September , the storm vias cent ered over

Los Angeles and produced rains of unprecedented scale over all of

Southern Calif ornia . Los Angeles recorded 5.5 inches; Mount l'ulson,

13 inches Ros endal , 1962) ; and San Diego, 2. 5 inches Koeppe, 1958) . ( ( U.S. Weather Bureau reports and Los Ar�eles Time s temperature account s

are given in Appendix A.

No other tropical storms or hurricanes have come so far north

along the coast , but several have crossed it 1vithin a few hundred

miles of San Diego Willson, 1921; Wi lgus , 1963; Aldrich and ( Meadows, 1966) . Host storms are felt only through their influences

on local phenomena : out-of-season precipitation, cloudiness,

occasional high temp eratures, and increased surf along the coast .

Two tropical storms , in 1889 and 1908, probably reached as far i north as San Diego according to .Aldrich and Meadows 1966) In i ( . September 1918, a tropical cyclone centered off Baja California was

: assumed responsible for rains in California during the same period

Tingley, 1918) . (

San Diego Wi llson, 1921; Blake, 1935). On 30 September, Yuma, ( Arizona recorded 3. 63 inches of precipitation as a result of this

storm. As the storm proceeded northward it did not dissipate as is 32

usual, but continued in the .midlatitude westerlies to the East Coast, to produce the longest recorded track, 7,000 miles (Hurd, 1929a).

Eight years later, another tropical storm brought precipitation to the Southern California area as it moved up the coast and into

San Diego on 17 Sept ember 1929 (Hurd, 1929b ; .Aldrich and Meado1-rs,

1966) •.The abnormal weather, very similar to that described in

Appendix A for the 1939 tropical storm, was presented by Blake ( 1929). i Desert air pulled toward the coast by the low pressure tropic al syst�� offshore, brought maximum temperatures of over 100 F on the

16th and morning temperatures of 90 F and above in San Diego on the

17th. The coast recei ved 0.21 inches of precipitation, the mountains reported hea�J rain, and the Los Angeles area was reported

to have also been affected.

On 28 September 1932, a tropical cyclone moved northward from ° 19°N, 107 W, and dissipated over the Southern California mountains, causing thundershowers, hail, and snow, killing 15 persons and doing drunage totaling $1 million. Precipitation totals for the Tehachapi

Mountains area were (Sprague, 1932) :

September/October 28 29 30 1 Total

Inches 2.14 0.17 2.20 2.60 ?.11

On 8 August 1936, stratocumulus clouds marked the begirL.J.irig of unusual lfeather conditions in Los Angeles, which later resulted in

squall 1dnds, high humidity, and heavy overcast (Ward, 1936) . A tenth of an inch of precipitation was reported on the 8th, with more falling on the 9th. A.Yl intense tropical st orm had moved north from ° ° its origin at 18 N, 106 W (Blake, 1937a) up through the Gulf of 33

California, and continued through Southern California (Hurd, 1936) .

Blru(e (1937b) used aerological soundings for San Diego, Billings,

Cheyenne, and Salt Lake City to follow the air mass, attended by thunderstorms and rain. By 13 .August it had moved into the I1ontana- Idaho area before losing its distinguishing characteristics of high

equivalent potential temperature and high specific humidity.

Tn e last tropical cyclone noted as affecting the west coast of the United States before 196l occurred in .August 19.51 , when one inch

I 'of precipitation was reported in San Diego (Koeppe, 19.58) .

4.2 Tropical Clclone Activity in Baja California and the Hexican Nainland

Tropical cyclones have caused extensive damage in Baja

California and western Ma�ico more often than to the west coast of the United States. However, only a fev1 of the more severe storms have been cited in previous literature . El Cordonazo de San

Francisco--The Lash of Saint Francis--has been greatly feared by

Baja Californians for ma� generations . Tn ese violent southeasterly and southerly winds along the Mexican ivest coast, usually associated with tropical cyclones a short distanc e at sea, are so named because of their usual occurrence on or ab out 4 October, the feast of

Saint �r ancis (Kalstrom, 19.52) . Hurricanes and extreme tropical

are still referred to as El Cordonazo, their date of occurrence

no actual significance.

The first documented El Cordonazo occurr ed on 1 November 1839, 12 boats ru1d all persons on board were lost in the harbor at 34

Mazatlan Hurd, 1929a) • Another storm claimed three boats at (

San Blas in 1840 Kalstrom, 1952). In 1881, two storms with estimated • ( winds of over 100 knots hit Mazatlan and Manzanillo Rosendal, 1962) . ( Mazatlan was again the scene of destructive hurricane forces in

· October 1957. At that time one large freighter and 20 slU'imp boats

were beached, while 20 more w·ere sunk . Mazanillo Has also visited

i again on 27 October 1959. Estimated Hinds of 1 35 knots--the wind

'equipment had registered 127 knot s before it was blown down- -attended

the hurricane . Along the coast six He.xican merchant vessels and one

naval ship viere sunk . Mexico City reported extensive destruction,

with a death toll of 1,000 DeAngelis , 1967) . ( Hurricane Tara, on 12 November 1961, swept across the coast

between Acapulco and Zihuantanejo taking an estL�t ed 500 lives

Rosendal , 1962) . Tropical storm Hazel of to Sept emb er ( 23 26 1965 moved inland just south of Hazatlan with winds of 59 knot s, killing

six persons, wrecking 30 fishing boats, and causing another $1 million

in damage. An estimated 1 0,000 people were evacuated from low lying

areas because of stream flooding caus ed by extensive rainfall

. Baum, 1966). ( The first tropical cyclone of the 1966 season, Hurricane Adele,

went ashore about 100 miles south of Manzanillo, causing considerable : flooding and several deaths before it dissipated. In late

September, Tropical Storm Kirsten heavily damaged or destroyed 180

homes and killed six people before it dissipated over the Mexican

mainland Baurn, 1967). ( Ii In 1967, Hurricane Katrir�--29August to 2 September-- produced i about $5 million darr�e in San Felipe as it crossed Baja California

and turned no+th up the Gulf of California. One person was killed,

5,000 were stranded, of San Felipe was destroyed, and the half highway to Mexi.cali v1as washed out . Two -thirds of the town 's shrimp

fleet was completely ruined and about vessels along the coast vrere 6o wrecked. A second damaging hurricane, Olivia--5 to 15 October--"'vith

110 knot winds , crossed the Baja California coast unleashed her and strength upon the town of Mulege. T'.ae tovm remained isolated full for several days, th most of the 1500 t people homeless; two id owns drownings were reported. PART II : PRECIPITATION

CHAPTER V

11ETHOD'3 TECHNIQUES AND

5. 1 Need For Subjective Analysis

No ob jective criteria are available to distinguish rainfall

caus ed by tropical cyclones from that caused by other processes .

Cry (1967) enc ountered this same problem during his study of the

Eastern and Southern United States . He identified tropical cyclone

precipitation as that occurring along the East Coast up to the time

of storm dissipation. Since tropical cyclones within his area of

study do cross the coast, this method was acceptable, lvhile such

criteria could not be implemented in a stuqy of the West Coast of the

United States as is presented here .

When a tropical cyclone crosses the coast, the attendant

precipitation usually can be attributed to it , but few tropical

1 cyclones cross the Hexican and California coast lines ; of the 74

tropical cyclones which occurred from 1961 to 1967, only two crossed

the coast in th e vi cinity of Southern California Section J.J). ( Tropical cyclone effects on Sout hern California precipitati on

arise primarily from the tropical air mas s impelled northward by

dissipating storms . Precipitation caused by such activity is

considerably more difficult to identify than precipitation directly

associated with tropical cyclones .

36 37

Analysis of synoptic weather raaps , aerologic soundings, and satellite photography helped somewhat in identifying tropical systems potentially responsible for precipitation in Southern California, but considerab le subjective analysis of the data was also necessary.

Storm strength, area of dissipation, storm track in the fevi day s before dissipation, and the amount of precipitation occurring- were all scrutinized carefully . No boundaries, rules, or upper-loi>J"er limit s could be used to determine what precipitation was or was not caused by tropical cyclones or the lingering tropical air masses of dying hurricanes or tropical storms . Any marginal situation was excluded, to insure that the final result would be a minimum figure for the amount of precipitation caused by tropical cyclone activity .

The major aim of this thesis is to present the effect of hurricanes and tropical storms up on Southern California as the percentage of annual precipitation . Thus the primary methods and techniques are oriented to the analysis of precipitation itself .

5.2 Precipitation Station Network

-�4 extensive network of recording rain gauges throughout

Southern California, necessary to show the effect of tropical cyclone precipitation, was chosen. Forty rain gauges from Santa

Barbara to the Colorado River were selected from thos e presented in

Hourly Pr ecipitation Data, California (U.s. Department of Comi1lerce, 1961 -19671;>).

Only stations with continuous records and no station site changes during the seven year period of study were chosen. Hourly data provide greater accuracy, in both data collection and reduction, : !than once-daily readings. Two stations in Arizona, Wikieup and

:Yuma (U.S. Department of Commerce, 1961 -1 967a) , both just across

·the Colorado River, were added after preliminary studies shm·1ed they would provide significant details on the precipitation distribution along the southeastern border of California.

All available hourly records in the Colorado and Mojave

Deserts w·ere used, while only a few of the stations in the greater

Los Angeles area were included. Tn e stations, numbered for ease in reference are listed in Table 6, and shown in Figure 9. Of the

42 stations, 7 are considered coastal, 9 mountain, and 13 desert .

The remaining are combinations and caru"lot be classified in detail .

The nmnb er of stations at various elevation intervals ab ove sea

level are presented in Table 5.

Table 5. Precipitation Stations Per Elevation Intervals

Elevation in feet 0-1 00 100-500 500-1000 1000-3000 3000-5000 over 5000 Numb er of stations 5 1 3 6 2 t$ t$ Table 6. Precipitation Stations Us ed in Tn is Study

Map Index Stations No . No . Lat . N. Lon . Elev. Feet g \{ .

CALIFORNIA

San Diego County San Diego Airport 1 1 i·rB 7740 32 117 10 3 44 1 Morena Dam 2 .5840 32 41 116 3 307.5 Crawford Ranch 3 2139 32 .53 116 17 1,500 Julian \>vynola 4 4418 33 06 116 39 36.50 Oceanside Prunping Plant .5 6379 33 13 117 21 30 Palomar Mt . Observatory 6 66.57 33 21 116 .52 .5.54.5 Warner Springs 7 9447 33 1 7 116 38 3180

Imperial Count;y: Centro El 8 27 1 3 32 46 11.5 34 30

Orang e Count;t Laguna Beach 9 46.50 33 33 117 48 210 Modena 10 11 El 277.5 33 48 7 47 464

Riverside County Elsinore 11 280.5 33 40 117 20 128.5 San Jacinto Ranger Station 12 781 3 33 47 116 .58 . 1,560 Riverside Experimental st . 1 3 7473 33 .58 117 20 101.5 Thermal F Airport 1 .AA 4 8892 33 38 116 10 120 Hay field Pillnping Plant 1.5 385.5 33 42 115 38 1 370 Blythe 7 W 16 092.5 33 37 114 43 390

' ------·-·------·---··------··------·------·-·· ------·------···-· ----�------�------(-.,_- .. ---- � --···------40

6. Table Precipitation Stations Used in Thi s Stuqy ( Cont . )

Nap Index Stations No . No . Lat . N. Long . W. Elev . Feet

CALIFORNIA :.

: San Bernardino County � Etiwanda 1 7 2895 34 08 117 31 1390 , Cajon 1.-Jest Summit 18 1272 34 23 117 34 47 80 ' Victorville Pumping Plant 19 9325 34 32 117 18 2858 Big Bear Lake Dam 20 0742 34 14 116 58 6815 Iron Hountain 21 4297 34 08 115 08 922 Parker Reservoir 22 6699 34 17 114 10 738 Needles 23 61 15 34 50 114 36 4.80 .Amb oy 24 0176 34 34 115 45 635 1 25 2255 34 52 116 52 1975 Daggett ffi�E Baker 26 0436 35 16 116 04 940

, Kern County · Boron 27 0979 35 00 117 39 2460 Tehachapi .� rport 28 8832 35 08 118 26 3960

Sant a Barbara County Santa Barbara 29 7902 34 25 119 41 5

Los Ang eles County Palmdale 30 662)� 34 35 118 06 2596 Tujunga Mill Creek 31 9049 34 23 118 05 4645 Acton Escondido 32 001 4 34 30 118 17 2920 Burbank Valley Pump Plarit 33 1194. 34 11 118 21 655 Chatsworth Reservoir 34 1682 34 14 118 37 91 2 Bel Air 35 0619 34 05 118 27 585 Los Ang eles Airport 36 51 14 33 56 118 23 WB 97 Los Ang eles Civic Center 37 51 15 34 03 118 14 270 Signal Hill 38 8230 33 48 118 10 100 San Dimas Tanbark Flat. 39 7750 34 12 117 46 2720 Diamond Bar Hors e Camp 40 2432 33 59 117 50 740

ARIZONA

l1ohave County Wikieup 41 9309 34 113 37 2125 44 Yuma County Yuma 42 9662 32 114 37 1 38 44

----···· --.-··-···- ··-·· ·------· ·------L----· ··-··--· ------··---- ···-··· ··------. ------· ------·------...------1 I' . ;li § ' ·-· .... 36° 0120 1 ° 119°1 118°1 111 7° --- l· 115° r·-' .1 14° 113- � ------. T _n.6 -- ,------�K 7 • 6• • I ° 'b I \ 33 � � 3 r1 \."• 33 • I \ • 8 -- 2 I _ ..,....,.· _ •42 • ___; - - - - � -- I - l...... 32°120° 1190 118° 115° .....114 °...... 11332 ...... o ..... o

9 I . I Figure . Precipitation Station Network Used in This Stu�. ·-·-----··------···------·------··---·-··-- ·-··---·------·-·-··-··---·-·--· ------··------·------·------·· ·-·------1

f:; --··-·--s·:-3- ;;��;��-�-·-i���·��;��------. - The lack of objective criteria made it necessar,y to identify I 1 the tropical cyc�one precipitation by the precipitation data itself---�l. Two procedures were needed to limit the masses of precipitation

data to manag eable quantities : a maximum distance of tropical

cyclone precipitation effectiveness, and a time lag between tropical

c.yclone occurrence and rainfall in Southern California .

For two reasons, a tropical cyclone was not expected to cause

rain in Southern California until it was within 500 miles, south to

west, of San Diego (Dotted Area - Figure 10) . Normal hurricanes

produce gale winds--40 mph or greater--within 350 to 400 miles of

the storm center; lesser storm characteristics can be assumed to be

felt within a much larger radius and Miller, 1964). Along (Dunn the East Coast of the United States, intense hurricane precipitation

was reported within 300 to 500 miles of the hurricane eye--storm

center--and, on severe occasions, rainfall proceeded the hurricanes

by as much as four days (Schaner, 1968) . At a slow speed of six

knots for hurricane movement, rain four days early represents

precipitation 500 to 600 miles distant from the storm center.

For easier tabulation of existing tropical cyclone data, this

tentative 500-mile radius was modified to a "potential zone" . extending from 105 0W to 1250 W and north of 250 N (hatched area, 1 .Figure 0) • storm occurring within this area was considered .Airy capable of producing precipitation in Southern California. Tracks

(Appendix B) of t e 74 tropical cyclones which occurred from 1961 h to 1967 (Table showed oricy" 1.3were still active in "potential 3), the �-----· c------·-·"··--: ------... r-r=: : ... -1I 1 r ...... e b ...... 1961�1967 I . Potentially Effectiv Tr pical C,yclones . . . I . 1 3 Orla (TS)1961 Claudia ( TS)1962 2 September 4 September Bernice (TS)1962 Doreen (H) 1962 September 5 October Katherine (TS)1963 6 · September( tsl ClaUdia 1965 1 August 1965 ' 8 Emily · (H) 00 August 1966 5 9 Helga (H) ' Original Mile September Kirsten (TS)1966 Radius, So�uth to West � � ��go September('IS } � 0 - �• � 0 July 1967 _ . � >� }- 20<\::' � " \ Francene �- I' I \ � � �l l Katrina (H) 1967 Modified Area: ' "Potential Zone11 ' LilyAu gust 1967 ' (H) ' Septe· mber 1967 Effective. l\\\\\\ \\\\ Storms\\\) ' Olivia (H) I - ;II'/ ' October � �- ...... _ Non-effective 120° 0 ' \ 0 ..,.. __ _ _ ..... 8 Storms ,1'1 - "ThQ">-

I 10.

__ I Figure Potential Zone and Potentially Effective Storms . __ L j

e; ·

--zone·- ---·· ·-··-····-11; their···-· ··------·-·-·--·---- tracks are .found------in Figur--···--·-e ---- 1 0.------·-- ·--·--·------····---·----

', A preliminary estimate o.r 10 days .for the possible time lag .for

·precipitation to occur after a storm had entered the "potential zone" was reduced to se' ven d�s. after �sis of the precipitation data of the 13 cyclones which entered the "potential zone". In

several instances, no precipitation was accounted .for at or all, precipitation in Southern California could not be considered

associated with tropical cyclone activity because of either the

time differential or the type characteristics determined by .further

study.

� seven storms appeared to have been effective in producing

precipitation in Southern California. These seven storms, shown by

solid lines in Figure 10, are discussed in detail in the next

chapter.

5.4 Supplemental Techniques

Weather maps, aero logical soundings, and satellite photographs

were used to study the seven storms identified by tracks and

precipitation records .

Daily weather maps published by the S. Weather Bureau were U. studied to detect tropical air movement .from the Mexican west coast .

I However, observations in the eastern North Pacific were so infrequent that a hurricane or ext.reme tropical storm was shown onl.y

after it approached within 100 miles or so of Southern California.

The maps did permit identificati on of precipitation in Southern

---·------· ------· C f ed t ro � thana�� byo= trop��;,.ical cyc�-lones-�:=�a�- to =:��: the south;;. �This��= identific=::��:,-r:�ation contributed to the final delineation of tropical qyclone �nduced

I precipitation.

To determine mass characteristic s attributable to tropical air cyclonic activity, adiabatic charts, compiled by the U. S. Weather

1.j Bureau , Los Angeles office, were accessible. None of these

soundings was similar to the tropical hurricane structures given

by Blake (1937) and Schacht (1946) . Since upper analysis has air been vast� improved and refined over the past 30 years, this

difference does not necessari� indicate change in the structure aqy of tropical cyclones in that period. Just as the weather map data

helped eliminate precipitation caused by frontal activity, the

aerological soundings also indicated non-tropical precipitation.

During several periods thought to be influenced by tropical cyclone

activity, the soundings showed high relative humidities but low

temperatures, which indicated non-tropical conditions .

Satellite photographs , obtained through the Atmospheric

Science section. · at Point Mugu Naval Missile Center, provided

pictorial proof of the presence of tropical cyclones in the area

and of the range of their effect. Unfortunately, a satellite

photograph of a mature tropical cyclone shows clouds , with the

underlying land almost totally obscured. Hence, such pictures do

not provide much detail on actual effects.

______l ______j ,------5�-5- -����-��--��------. ------1 . To best depict the effect of the seven storms certain standard

I . I statistical operations on the data were required (Panofsky and I _ J Brier, 1965) , with some modifications .

The basic expression used is the percentage of annual precipitation caused by tropical cyclones: I

= a/b Z 100 where is precipitation caused by tropical cyclones and b is the ! total precipitation in the calendar year in which the storms

occurred. This figure was tabulated for each station for six of the

seven years of the study; no "potentially effective" storms occurred

in 1964. .Annual precipitation, tropical cyclone precipitation, and

yearly percentages are presented in Table 1 1. The calendar year was chosen rather than either the rain year

or the water year, used by various agencies for Southern California

precipitation. The water year--october to September--would cause

confusion arising from late season tropical cyclones occurring

October. The rain year--July to June--would produce similar in results at the beginning of the tropical cyclone season, with June

storms .

Four different averages of the annual percentage of rainfall

caused by tropical cyclones were computed for each station (Table 8).

Two of the percentages (Y ) and (Y ) .are means of the al a b annu percentages for, respectively, the entire seven years of the stud;r

and the six years excluding 1964 when no tropical cyclones produced

______Il_ _ 4{

- ..... ____ r·· ...... - ·-·----· --- - ... -- - . - -·-- . ... ------...... ··--···. --- TABLE Tropical Cyclone Precipitation, ual Precipitation, . --·l ... ------and Ann 7. as a Percentage of the ' ·-" Tropical Cyclone Pr�cipitation 1 , Annual Precipitation

j -.· '

. ; < . 1961 1962 1963 Tr. Cy. Cy. Cy. Ann . Tr. Ann. Tr. Ann. ·· station . Prbc . Prec . Prec . Prec . % Prec. Prec. I % %1I Acton Escondido 0�15 4.51 3.3 0.17 9.22 1.8 0.19 8.21 9.6' Amb oy o.oo 1.53 o.o 0.00 0.41 0.0 1.37 2.78 49.3: Baker o.oo 1.00 o.o 0.05 0.15 6.7 1.55 3.64 42 .6� Air 0.02 7.83 1.3 0.03 22.08 0.1 0.44 15 .70 2.8! Big Bear Lake Bel Dam o.oo 18.36 0.0 o.oo 32 .47 0.0 4.16 31.10 13 .2l Blythe 1 W o.oo 1.42 o.o o.oo 2.20 o.o 0.51 4.09 4.3; Boron o.oo 1.63 o.o o.oo 2.08 o.o 1.06 4.24 25.0;

Burbank Valley Pump . 0 .• 03 7.44 0.4 o.oo 17.54 o.o 0.51 13.14 4.3I Cajon West Summit 0�00 5.51 0.0 0.00 8.62 o.o 2.70 10.00 27 .0, Chatsworth Reservoir 0.00 7.60 o.o 0.05 17.12 0.6 0.32 13.94 2.3j Crawford Ranch o.oo 5.52 o.o o.oo 3.62 o.o 1.40 5.64 24.8: Diamond H. Bar c. o.oo 6.03 0.0 o.oo 15.15 o.o 2.13 15.91 13.4 Daggett 1 ENE . o.oo 1.81 o.o o.oo 1.86 0.0 1.38 3.27 42 .21 E1 Centro . o.oo 1.74 o.o 0.00 1.92 0.0 0.91 2.12 45 .8\ Modena KJ.. o.oo 5.01 o.o o.oo 10.24 o.o 1.99 14.45 13.8f Elsinore o.oo 6.26 o.o o.oo 13.02 o.o 2.54 14.02 18.11 Etiwanda o.oo 5.64 o.o o.oo 13.93 0.0 2.65 15.61 17.0;

Hayfield Pump . o.oo 1.29 o.o 0.05 1.03 4-9 o. 90 2 • 81 32 • oi Iron Mo'llntain o.oo 1.39 o.o o.oo 0.87 o.o 1.51 3.45 43 .8; Julian Wynola o.oo 12.46 o.o 0.03 15.67 0.2 1.91 18.83 10.11 Laguna Beach 0.01 4.45 1.6 o.oo 9 -13 o.o 2.04 15.76 12.9i

L.A •. Airport WB 0.04 5.05 0.8 0.00 15.02 0.0 0.94 13.51 7 .o: I L.A. Civic Center 0.01 5.83 0.1 0.00 15.37 0.0 0.58 12.31 4.7l Morena Dam o.oo 6.74 o.o 0.03 13.92 0.2 1.15 15.55 7.l.t! Needle's 0.05 2.18 2.3 0.17 1 .13 15.0 0.99 3.83 25.8: Oceanside Pump. o.oo 4.46 o.o o.oo 9.14 o.o 1.11 11.35 9.8: Palmdale 2 NE o.oo 2.26 o.o o.oo 4.96 o.o 0.10 6.95 1o.1i Palomar Mt . Observ. 0.05 12.18 o.4 o.oo 14.88 o.o 2.50 20.36 12.3: Parker Reservoir o.oo 3.29 o.o 1.01 3.51 28.3 o.8o 4.48 17.9, Riverside Ex:p. St . o.oo 3-45 o.o o.oo 6.37 o.o 2.90 10.90 26.6: San Diego Airport WB 0.00 4.61 o.o 0.00 7.39 o.o 1.00 7.72 13.0' San Dimas Tanbark o.oo 12.54 o.o 0.03 21 .52 0.1 3.10 20.77 14.9, San Jacinto Rng . St . 0.00 4.86 o.o 0.05 8.41 0.6 2.85 12.05 23 .6: Santa Barbara o.oo 8.16 o.o o.oo 21 .40 o.o 0.45 20.31 2.2! Signal Hill o.oo 4.51 o.o o.oo 12.72 o.o 1.00 14.20 7.0[ Tehachapi Airport o.oo 6.25 o.o 0.03 9.31 0.3 0.79 12.53 6.31 Thermal Airport o.oo 1.26 o.o 0.04 1.19 0.3 1.35 3.32 40 .7 Tujunga MillFAA Creek o.oo 9 -47 o.o o.oo 14.66 0.0 1.90 15.78 12.0i! Victorville Pump. o.oo 1.86 o.o o.oo 1.93 o.o 1.99 5.14 38. 7j Springs warn er 0.31 6.09 6.1 o.oo 11.11 o.o 1.71 14.59 11.71 Wikieup 5.2 21 0.28 5.35 1. 6 6.39 �0 31 .6 Yuma o.oo 2.1 o.o 7 1.16 2.6644 7.72 1 7 o.oo o.o 4.67 57 · IL------·--�------�--�-·--j 48

------·--- -·------·------·------r--·- -- '- ---- �---· ·-· ------· -·-·-- . ------TABLE� 7. Tropical Cyclone Precipitation, Annual Precipitation, and · Tropical Cyclone Precipitation as a Percentage of the ------1 I Annual Precipitation (Cont.) I 1965 1966 1967 i Tr. Cy. Ann. Tr. Cy. Ann. Tr� Cy. Ann. Station Prec. Prec. % Prec. Prec. % Prec . Prec. % 0.02 15.58 0.1 0.43 1.53 5.1 0.33 12.06 2.7i1 Acton Escondido o.oo 4.35 o.o ·o.oo 1.60 o.o o.52 1.72 30.2:I I Amboy 0.00 5.44 0.0 0.16 2.05 7.8 0.00 2.09 0.01 Baker 0.08 25.00 0.3i I Air 0.12 27.35 0.4 0.0 0 14.65 0.0 Bel o.oo 59.84 o.o 0.6 3 33 .73 1.9 o.oo 51 .23 o.oj Big Bear7 Lake Dam 0.00 6.20 0.0 0.00 1.97 0.0 0.98 3.25 30 .2- Blythe W 0.00 9.13 0.0 0.18 2.19 8.2 0.35 6.80 5.1,1 Boron 0.22 26.29 0.1 0.00 12.52 0.0 0.21 20.22 1.0 Burbank Valley Pump. 0.00 16.27 0.0 0.00 8.30 0.0 0.00 14.14 1 Cajon West Summit 0.16 24.32 0.1 0.08 12.03 0.7 0.10 16.88 O.O0.61i Chatsworth Reservoir· 0.00 5.94 0.0 1.02 2.56 39.6 0.81 6.66 12.21 Crawford Ranch 0.04 23.66 0.2 0.03 13.29 0.2 o.oo 20 .49 o.o Diamond Bar1 H. c. 0.00 7.59 0.0 0.10 1.77 5.6 0.78 4.47 17.41i Daggett ENE 4.30 33.7 El Centro 0.00 2.87 0.0 0.92 1.50 61 .3 1.45 1 El Modena , 0.03 18.83 0.2 0.22 11.68 1.9 0.03 13.66 0.21 Elsinore o.oo 15.02 o.o o.o6 6.53 0.9 o.oo 10.40 o.ot Etiwanda · · 0.11 21 .92 0.5 0.24 17.64 1.4 0.07 18.08 1.01 H�ield Pump. 0.00 4.16 0.0 0.40 1.84 21 .7 1.04 2.46 42.31 Iron Mountain 0.00 5.50 0.0 1.38 3.70 37.3 1.54 4.26 36.2 Julian Wynola 0.10 19.68 o.5 0.88 26.o5 3.4 o.oo 20.05 o.o:j Laguna Beach 0.00 17.86 0.0 0.00 9.26 0.0 0.30 15.35 2.0 L.A. WB Airport 0.02 16.81 0.1 0.18 9.36 1.9 0.01 15.90 0.1!1 L.A. Civic Center 0.11 26.81 0.4 0.30 12.91 2.3 0.41 23.66 1.7 Morena Dam 0.17 26.29 0.6 0.14 15.89 0.9 0.87 17.93 4.9J1 Needles 0.10 8.31 1.2 0.37 2.93 12.6 0.18 2.12 8.5! Oceanside Pump. 0.00 18.58 0.0 0.00 8.71 0.0 0.04 12.98 0.3\ 2 NE 0.12 9.16 1.3 0.37 4.96 7.5 0.26 7.86 3-3\ PalmdaleMt . Observ. 0.00 23.12 0.0 0.32 28.89 1.1 0.49 19.54 0.01 PalomarRes ervoir 0.28 9.26 3.0 0.41 3.55 11.5 0.59 4.6o 12.8! RiversideParker Exp. St . 0.00 14.87 0.0 0.49 5.25 9.3 0.31 6.71 4.6j San Diego WB Airport 0.03 19.03 0.2 0.02 7.18 0.3 0.15 11.21 1.31 San Dimas Tanbark 0.40 42.65 0.9 0.23 25.79 0.9 0.40 34.28 1.2 1 San Jacinto Rng.St. 0.00 18.08 0.0 0.00 7.94 0.0 0.37 13.17 2.8 ; Santa Barbara 0.08 21 .01 0.4 0.00 15.93 0.0 0.00 20.80 0.0 1 Signal Hill o.o6 17.06 o.4 o.o5 8.53 o.6 o.oo 15.o6 o.o: Tehachapi Airport 0.25 11.17 2.2 0.20 8.19 2.2 0.87 13.56 6.4j Thermal .Airport 0.00 3.86 0.0 0.19 1.00 19.0 0.25 4.15 6.0j Mill 0.05 30.92 0.2 0.83 19.30 4.3 1.39 26.68 5.21 Tujunga FAA Creek 0.05 6.64 0.2 0.15 2.51 6.0 0.26 3.81 6.81 I Victorville Pump. Warner S,prings o.oo 21 .92 o.o 0.07 12.57 0.6 2.09 16.38 12.8 \ Wikieup 0.00 17.02 0.0 0.96 6.39 15.0 2.44 12.96 18.8 I o.oo . 5 6.9 2.2o .77 1 4 a_ __ _ 4 46o _ _o._o _. _o .o_1 1_�_o1_ ____ j Yu�--- _ J ···--- .... ------,.---·-··· ------... ------r - - ···------·------·-··------I TABLE 8. Total Annual Precipitation, Total Tropical Oyclone Precipitation, and Tropical Oyclone Precipitation I Percentages I I Total Annual Total Prec;pitation Tr. qy. (Y ) (Y ) (Y ) (Y ) a b c d I · Station 6 7 Yrs . Prec . I Yrs . ! Acton Escondido 57 �11 62.92 1. 89 3.3 4.4 3.0 3.3 .Amboy 12.39 13.11 1. 89 ll.3 13.3 . 14 -4 15.3 jI Baker 14.97 15.97 1. 76 8.2 9.5 ll .O ll. 8 Bel 112.61 55 0.6 0.7 0. 8 0. 6 0. 6 Air 123. 9 Big Bear 226 248.08 4. 79 2. 2 2.5 1.9 2.1 I Lake Dam .73 II Blythe 7 W 19.13 19. 94 1. 88 7.5 18.7 9.4 9. 8 I I Boron 26.07 28.15 1. 59 5.5 6.4 5.6 6.1 Burbank Valley Pwnp. 97.15 105.56 1. 03 0. 8 1. 0 1.0 1.1 Cajon We st Summit 62.90 69.14 2. 70 3. 9 4.5 3.9 4 -3 Chatsworth Reservoir 101. 69 0.71 4.5 5.2 0. 7 0. 8 91.89 Crawford Ranch 2�.94 31. 65 3. 23 ll .O 12. 8 10. 2 10. 8 Daggett 1 20. 22.6 2.26 10. 7 10. 0 10.9 ENE 77 7 9.7 Diamond ll5 0 123. 24 2.20 1. 9 2. 3 1. 8 1.9 c. .3 Centro 4 45 15 4 20. 1 2 5 22. 1 2 .1 El Bar H. 1 . .12 3. 3 3. 3 Modena 2. 8 El 73.93 80.67 2. 27 2.3 7 2. 3.1 Klsinore 65.25 13.53 2.6o 2.7 3.2 3.5 4.0 Etiwanda 92. 82 104.70 3.07 3.7 4 -3 2.9 3·3 Hayfield Pump. . 1 3.59 14.19 2.39 14 - 4 16. 8 16. 8 17.6 Iron Mountain 19.17 20.11 4.43 16. 8 19. 6 22. 0 23.1 Julian Wynola ll2.7 4 130. 26 2. 92 2. 0 2.3 2. 2 2.6 Beach 72.41 77.65 2. 41 2.3 2. 8 3.1 3·3 Laguna L.A. Airport 5.65 82.16 1.1 1. 4 1. 7 1.4 1. 6 1-JB 7 9 L.A. Civic Center 99.89 104.87 1.41 1.3 1. 5 1. 3 1. 5 Morena Dam 96.32. 110. 99 2. 36 2. 0 2.3 2. 1 2. 5 Needles 20. 50 22.27 1. 86 9. 3 10.9 8.4 9.1 Oceanside Pump . 65.82 72.19 1.15 1. 4 1. 7 1. 6 1.8 Palmdale 2 5 0 1. 45 3.2 7 6 4.0 NE 36.1: 39 -9 3. 3. Palomar Mt . Ob serv. ll8.97 138.41� 3.36 1. 9 2.3 2. 1� 2. 8 Parker Reservoir 28.75 30.42 3.09 10.5 12.3 10. 2 10. 7 Riverside Ex:p. St . 76.30 81. 99 3. 70 5.8 6.8 4.5 4.8 San Diego Airport 5 4 62. 41 1. 20 2. 1 2.5 1. 9 2. 1 WB 7.1 San Dimas Tanbark 157.55 174.55 4.16 2. 2 3.0 2.4 2. 6 San Jacinto Rng . St. 64.51 73-14 3-27 3.5 4.5 4.5 5.1 Santa Barbara 107.61 120. 40 0.53 0.4 0.4 0.4 0.5 Signal Hill 72.08 77.28 1.11 1. 1 1. 3 1. 4 1.5 I Tehachapi Airport 61. 01 70.53 2.14 2.5 2.9 3. 0 3-5 Thermal FAA Airport 14.75 16. 35 1. 83 9. 4 ll.O 11. 2 12. 1� Tujunga Mill Creek 116. 81 128.35 4 -17 3.1 3.6 3.2 3.6 Victorville Pump. 21. 89 23.12 2.45 7.4 8. 6 10. 6 11. 2 Warner Springs 82. 66 94.27 4.24 4.5 5.2 4.5 5.1 I Wikieup 57.83 66. 62 7.88 13. 1 15.3 11. 8 13. 6 Yuma 18. 6 20. 61 4.94 15. 7 9 I 3 18.3 23 - 26.5 I

L------·--·-- -·------·----- ··--· ···-- .. -- ---··------·-----·---.:...... I · ____ -·-- 50

- -- ·-· --· ------·- --"- -·--· ·------·-··-··--·-- ·------··------·------·------·--·--·-- -·---- ·-- ---·----- ,------. any detectable effects. The other two percentages (Yc) and (Yd) l 1 1. were derived from the seven or six year totals, respectively, of both annual precipitation and cyclone precipitation. 1! Damage reports are expressed similar� in the next chapter : I average damage per year for the entire seven years, and average I damage per year for the three years in which storms inflicted I I damage.

l______------_j - -

r------··--·····-· ·--····-···--··------, CHAPTER VI I Discussion

I Effects of the seven tropical cyclones which produc ed

detectable rainfall in Southern California during the seven years,

are discussed in this chapter. effects of each 1961 -1 967, First,

storm are given, in chronological order; then the total effect of

storms is presented. all

6.1 The Seven Storms

The effects of the seven tropical cyclones up on Southern

1 California are discussed, year by year, in this section.

Precipitation amounts for the period of study are presented in Tables

7 and 8, and storm tracks for all tropical cyclones, 1961 -1967, are

given in App endix

B. i Of tropical cyclones observed in the eastern north Pacific in 11 I 1961 , onl.y one, in September, produced identifiable effects in Southern California. Moderate rain reported during August and I Novemb er of that year could not be associated with tropical cyclone J

a.ctiv.l:ty :for the same months . Very little precipitation WIUI produced I

by the northwar d movement of Tropical Storm Orla--6-1 1 September. I ual Perc entages of the ann total precipitation (Table 7) occurring

during the cyclone influence were generall.y low, the highest being

6. 1% at warner Springs . Only 10 of the 42 stations had precipitation

attributable to the tropical cyclone, no storm damage was reported! and

during �la 's presence.

rainfall occurr�d sporadicall.y _ In 1962 _ thro��ut_!;�!_ ��c:_r j

------

-- - i-- --···-�------1 ·a.t· only a few stations . Late September and earzy- October I precipitation was attributed to the influences of Tropical Storm Claudia--20-24 September--which m?ved up the west coast of Baja I California. The precipitation amounts represented significant I percentages of the annual total : Needles, 15.0%; Wikieup, 21 .0%;

and Parker Reservoir, 28 .3%.

In 1963 tropical cyclone effects were heavizy- felt in Southern

California. On 18 September Tropical Storm Katherine crossed the coastline about 100 miles south of Ensenada, Mexico (Wilgus, 1964) .

Extensive precipitation was received at all the network stations from 17 to 19 September. Extremes reported were 4. 16 inches at Big

Bear Lake Dam and 0.32 inches at Chatsworth Reservoir . Percentages

of annual precipitation were very high, with a significant value of 49 .3% tabulated for Amb oy, and 56.9% for Yuma . The average

percentage per California station during 1963 was 19.1%; including

the two Arizona stations the network average rises to 20.3%. Heav,r

surf which preceded the tropical storm caused an estimated $5,000

damage in beach erosion along the Orange County coastline. Southern

California also incurred crop damage estimated at $5 to $50 million;

drying raisins, ripening dates, and tomatoes were most severezy

affected. Non-agricultural losses were estimated at $5,000 to . $50,000 . No deaths or injuries were reported. l In 1964, none of the six tropical cyclones which occurred in

the eastern North Pacific passed north of 25°N and thus were not considered to have potential influences upon Southern California. .I

The precipitation reported during the SUiliJJle1" coUld not be considered I

. I 1 . . �I ��s -� �f��t,--�f t��i�� i�xrl:c---��tirlty:------·--·------·------· ------··

I Tropical cyclone activity returned to normal during 1965; of I the 10 storms reported, only one, Hurricane Ein:i.J..y--29 August-4

I . I September--, caused widespread, but light precipitation at of half -. !J the stations . No damage was reported as only four stations recorded

I percentage values greater than 1%: Needles, 1 • 2%; P e, 1 • 3%; almdal

• d I Tehachapi Airport, 2.2%1 and Parker Reservoir, 3 0%. lilldlJ" ha I dissipated at 28°N, 1150W, ab out 150 miles west of Baja California I and north of the shear line discussed in section 3.3, in an area or cool ocean ter.wa

In 1966, extensive tropical cyclonic activity in the eastern

North Pacific was responsible for precipitation on two different

occasions . The passage or Hurricane Helga--9-15 September--over

Baja California produced precipitation recorded at 21 stations on

18-19 September. Ten days later, Tropical Storm Kirsten--25-29

September�-crossed Baja California and the Gulf' of California and

dissipated in the Sierra Madre Occidental . Precipitation amounts and

percentages of annual precipitation for the two storms are given in

Table 7. Precipitation amounts recorded during Hurricane Helga 's

influence were :

Acton Escondido ·29 Julian Wynola . 04 Baker .16 Los Angeles Airport . 1 4 Big Bear Lake Dam Los Angeles Civic Center .23 .42 Boron .10 Needles .25 Daggett .10 . Palmdale .10 Diamond Bar Horse Camp .03 Parker Reservoir .28 El Centro • 11 San Dimas Tanbark Flat .08 El Modena .12 Tujunga Mill Creek .15 H�field Pumping Plant .14 Victorville .02 Iron Mountain . 17 Wilieup Yuma

L. · ------· ---- __ I �:g� j 54

damage to non-agricultural activities . Strong wind and rain:;�

accompanied the storm and severely affected the specialty farms .

The rains of October caused by Kirsten resulted in even more 4 $50,000 $500,000 $500 $5,000 damage: to to crops and to to non- agricultural services .

By far the most active storm season within this study was that of 1967 when 18 tropical cyclones, 11 of which reached hurricane

intensity, were observed in the eastern north Pacific . The only

storm to cause tropical cyclone effects in the Southland, Hurricane

I Gulf I Katrina --29 August-2 September--was .funnelled up the of California after devastating Felip . She produc ed almost two :san � I inches of rain in Yuma, and large amounts in the eastern desert

I regions of California. Warner Springs recorded 2.09 inches, the ·

I highest precipitation of the California stations, while Wikieup,

I Arizona;. received 2.L4inch es. Surprisingly for a storm of this

nature, no crop damage was reported but estimates of $5, 000 to

$50,000 damage were reported by other agencies. The heavy rains

caused considerable flash flooding in the Coachella Valle,y,

particularly in Palm Desert �

6.2 Areal Distribution

Together, these seven tropical cyclones in seven �ears--none

L------· I ------, . ------�--- - , ------1 in 1964, two in 1966--caused rainfall totals in Southern California j ranging from less than an inch in western Los Angeles cowrty to more ! I I than .four inches at several stations from the San Gabriel Mountains

to Yuma . Most of the rain gauges east of the San Gorgonio and San

Jacinto Mountains received more than three inches of tropical

rainfall, or an average of almost half'-an-inch per year . Total precipitation associated with the seven tropical c,yclones from 1961

to 1967 is shown in Figure 11 • Since the average annual rainfall at

� or these desert stations was , during the seven years, around

two inches, the contribution .from tropical c,yclones is substantial

in extreme southeastern California.

During the seven years of stuqy, at least, tropical a,rclones

tended to introduce moist unstable air northward over the Gulf or California and up the Colorado River valley, so that the resulting

rainfall decreases to the north and west . In contrast, most of California 's rain is associat ed with the eastward motion of frontal

systems from the Pacific, with maximum precipitation on the coastal

mountains and a sharp decrease east of them. Consequently, the

ratio of tropical rainfall to total rainfall is greatest in the

desert areas .

Figures 12 to 15 show the areal distribution of this ratio,

expressed as a percentage, calculated in various ways . On all four maps, areas receiving more than 15% are crosshatched, 12% to 15%

are hatched, and 9% to 12% are dotted. · In all tabulations the far southeastern desert areas recorded percentages greater than 15%.

l, ---·------·- ---- ____ j ' '·

2 I r-·---...... I ° -��-"""" 11I I I 8 __"__ 117 11 4° _____ --- -� 1 �------"{�.. 11.f\. 11 roj �� I '· � I I '· ' I " . '� I \. . l.76 '. , � �- :> -,� -", " ipche:;; ...?()- ' 2.26 3 35 • \ 8 - . . 6 I ') '· ·7 .88 . .8 1 9 Ii I � �<@.. 0 3b5 I I () I 0." 0 �3 33° I

· < 3 .! .to · . I �neP.es � ?. 3 inches 0 0 "- 0 0 I 120° 119° 118 115 114"-...... _ 113 0 I II ...... 13 I 11 . from 1961 to 67 Figure .T: tal Precipi::-on Ass:�ted with the Seven Tropical Cyclones �9 �

� . = -== - = ::::· ·. · r 120° . 119° 118I I 'i 117�- - 11 ° \ 11 4° i I ° -· ------5 • �oj ·- ,,� i I •. --' j :·-·-j� 1#1 · -�. �· . i t. ' i \" . ,_ (. ' •8.2 ·,_ \ . . ·. ·.·. . ·. ·. . . . -. . 3.

• 13.1

I �"'---�0.. I J ..,.

""' 30 � 3.�0 9% - 12% � �5.1 12% - 15% .__ l ""'"' 15% 0 ...... 0 119 118° 1l1Cl...... 11 ° "0 120�� 3 3 nSO ......

12 . Mean of Annual Figure Percentages, Seven Years, (Y )• ______a ;._ ____j � ---�------� 36 ° ° !1� 1200------119° 118 117° 5 r-·-·-·��il4°

o· ....._1 '''i"'C) 35 3;;, '\·-,,

------� ;I 5.3 0.4 /I

I 34°

I I «:;)- -� 33° 33 9% - 12% .I :_::]' � *18 .3 l 12% - 1 5% I ·- --� 20 I 19° 80 11.s<> 1l4 -----.....___. 11- �-- --- a I i i

13. Mean of Annual Six

--···-·�-·------Figure----�- ----··------·--�------Percentages, Years, (Y ). L·--·------�·------· ------___ b · ___· j � ______..--. �,�"·�.. � .. �� I� o•r------��- ,------··T-o --- �r--. ------.�-o -r-. ---.-- .---.�- l�?l-: 'o-,. �-- -�� ll ll - - - "• ------r - � , rti 1 o- - - - - 119-o - - - - -8 -o , . 7 - - 11 ..,., 4 11 2 o 11 I . ��------I \. �

--,j�'',� .__ � '-- . 'l 1· - - \ - 3 I' - \ I 0.4,.. .11.8 }1! ° -·�;-�:-� .� .. 34

� c:> � ° ° 33 33

. . � <: J 1 9% - 2% - 1 1 .... - 2% - 5% ° ° O "11.0- ° � 11 11 ll ...... 11 1$% 9 8 11S - 3 ;:·,.'.

14. 1 Figure Percentages of Total Precipitation (Seven Years) Associated with Tropical C,yc ones, (Y )• --· ______c ---·------· j

' \1\ '0 ----1

··. . o � ' . __ 11 · ...... , ...:.. . - -11 I l r · I 2 I I ·· �! �---- __ � I ' r·. ---�4 °. �� )!:----. . .. ·.·-�K.. · �,. . . . 'J5°C, ° 1I �" --�8. _ I - \ .. .. :::::::::::ii;�� :::::::::::::·.·. ., ...... ··. _··· .··. . ·.· · · . · · . · _._. •3.5 . · · . . ,. \ � ' . I. 3�:� •13.6

0 . : 33° ? � 33° -·� 9% - 12% � :::: 12% - 15% 0 . ° 32 15% .... _- 32 2:. 1180 ...... 12o0 � o ·- -� � ll9° 114° i 15. I Cyclones, (Y ). i ted with Tropical ______F:ig ure Percentages of Total Precipitation (Six Years) Assocd.a _ d ]

8' 61 ::��:: o�O:: -�� d . area 's annual:;�7:o:: precipitt�:��:�u:ation was :associa�:::::ted�: with tropicalo��: c.yclones�o�=. Figures 13 and 1 5, portraying percentages for only the six years I in which tropical cyclones were effective, natura� present higher

values than Figures 12 and 14, which include a year without tropical cyclone effects . Figures 1T and 11 depict the extent of tropical c.yclone precipitation if such activity were' to occur every year, and . should be used for statistical and theoretical applicati ons only .

The two maps representing reality (Figures 12 and 14) are more significant. Figure 14 represents the precipitation totals for the entire stuey period, and contains significantly higher percentages

than does Figure 12, the mean of the annual percentages . On all four maps, six stations are in the region of maximum effect . At these stations--listed clockwise around the Colorado I· Desert--the seven year totals of all rainfall, of June-October

rainfall, and of rainfall attributable to tropical cyclones, are given in Table 9. Rainfall associated with tropical cyclones I accounts for almost all the precipitation of summer and early autumn, i and :ror one tenth to one quarter o:r the ;rear:cy total .

TABLE 9. Rainfall at Six Desert Stations, 1961 -1967 Station Total June-October Tropical G,yclone 1 I1 Centro I El 15.12 4.96 3.34 H�field Pumping Plant 14.19 4.35 2.39 .Amb oy 13.11 6.33 1.89 I Iron Mountain 20. 11 7 .90 4.43 j' Blythe 19.94 5.10 1.88 , 20.61 11.22 I ��------·------·---�·�--_j 62

·--··"-----·------·--·-·--··-·------.. -- ---·- ·· --··------· ------1 This rainfall, while significant climatically,- may be more j

damaging than helpful . It is too unreliable and inadequate to

contribute to the water supply, either for agriculture or domestic

use. In the Imperial and Coachella valleys, water is imported from the Colorado .River, and occasional rainfall is generally unwanted.

In some areas, tropical rainfall may contribute slightly to

groundwater, tapped by a few wells. But most of it evaporates,

after washing out the desert hillsides .

Damage is the major result of tropical cyclone precipitation

upon Southern California. Total damage from the seven years was

approximately $25.8 million, or an average yearly loss of $3 .7

million. Perhaps a more meaningful figure is that of the losses per

damaging storm, $8.6 million.

Since control of tropical cyclones still requires rigorous

research, warning of storms to permit advanced precautionar,y measures

is the most practical present means to decrease the damages .

Prediction of these storms is, however, a problem. Of the 74 tropical

cyclones occurring off the west coast of Mexico, o� 17 .5% were

active north of 25°N and east of 1250W, and hence might have

influenced Southern California; of these 53.8%--9.5% of all the

tropical cyclones--ac�ually had measurable effects. However, 27 .3% of 1 all September storms entered the 11potential zone 11 and all of them .

produced effects in Southern California; 46 .2% of all potential storms begam September. This may demonstrate a possibility for positive ! in I pre-planning for advanc ed preparation in the event of tropical ' I cyclone enroachment upon Southern C ifo a. . � � ------·--. ------·__j L ------····-1

CHAPTER VII SUMMARY AND CONCLUSIONS I

The primary purpose of this thesis has been to determine the effects and significance of tropical cyclones upon Southern California. The eastern North Pacific was shown as an area of

frequent tropical cyclone activity, second highest of all areas in

' the world, surpassed only by the western Pacific. Hurricanes and tropical storms occur from June to November, with September the month of highest frequency. The effect of the eastern North Pacific tropical cyclones upon the North lunerican west coast is highly dependent upon their

movement in the area. The general trend of tropical. cyclones is to

proceed north or northwestward from their origin area, which was found to be from 15°N to 20°N, and 100°W to 1100W. Increased detail on the nwnber and tracks of tropical cyclones, possible through weather satellites, caused the stuqy to be restricted to the years since 1961, when the first satellite was placed in orbit . subjective �sis was necessary to evaluate the A precipitation effects caused tropical cyclones, since no and b.y objective methods for such evaluation were available. A precipitation gauge network of 40 stations throughout Southern

California, and two Arizona stations, was selected. Storms were then classified as to potential effectiveness their positions at b,r the 13 time of dissipation. Of the 74 storms, fulfilled the location I requirement; each was ana.:cy-zed as to precipitation e ______l � � __ _ j1 63 64

------·-·------···-----·--· ·- ·-··------·------·�--··-----··------·--·--- -··------··- -- - -···------· ··- ··-·- -·- .. ------· · ,

production and general effect upon Southern California. 0� seven of these storms , occurring in six different years, had produc ed I significant percentages of the total annual precipitation and

damages in the millions o.f dollars . This stuqy shows that tropical cyclones do produce effects I I ' within Southern California, although not necessarily every year.

Since the precipitation occurs in the of.f season, both offensive

J and defensive planning are needed. Intense late er summ I precipitation may cause extreme damage to unprotected slopes, devoid

of vegetation.

During the seven year period, 10% to 25% of the annual

precipitation and a maj or portion of the June through October

rainfall, 75% in the Colorado Desert , was caused by tropical

' cyclones. Thus it must be assumed that tropical c.yclones are not

only aspects of the sunnner weather , but that they are significant .factors in the entire precipitation and climatic regimes o.f I Southern California . I II I I

L-----·· --�� J I · 65

------

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Helm, Thomas , 1961 : Hurricanes : Weather at Its Worst. New York, Dodd, Mead and Company, 234 pp .

Hurd, Wi llis Edwin, 1929a: Tropical Cyclones of the Eastern North Pacific Ocean. Monthly Weather Review, 51, 43-49 . �

1929b : The Mexican West Coast Hurricane of September 10-18 , 1929. Monthlz Weather Review, 51 , 391-398 .

1936: North Pacific Ocean, August 1936. Monthly Weather Review, 64, 211-216 .

1939a : North Pac�fic Ocean, September 1939 . Monthly Weather Review, 67 , 356-358 .

1939b : North Pacific Ocean, October 1939 . Monthly Weather Review, 61, 406 . Oct . 1939.

1940 : Additional Note on the Mexican West Coast Cyclone of October 23-25, 1939. Monthly Weather Review, 68, 29-30.

Ives, Ronald L., 1949 : Cliroa.te of the Sonoran Desert Region. Annals 2[ the Association ££American Geographers, 39, 143-187 . 1952: Hurricanes on the West Coast of Mexico. Pacific Scienc e Congress Proceedings, 3, 21 -31 .

1969 : Personal Communication. Jurwitz, Louis R., 1953 : Arizona 's Two -season Rainfall Pattern: Weatherwise, 96-99.

El Kalstrom, George w. , 1952 : Cordonazo - The Lash of St. Francis : Weatherwise, 5, 99-103 .

Kendrew, Wilfrid George, 1961 : The Climates of the Continents. London, Oxford at the Clarendon Press, �th pp . Ed. , 606 I Kimball, James H., 1915 : A Pacific Hurricane o£ September 1915 : Monthly Weather Review, 43, 486.

Koeppe, Clarence Eugene and George C. DeLong, 1958 : Weather Climate. New York, McGraw-Hill Book Co., Inc., 341 pp . �

Krick, Irving P. and Roscoe Fleming, 1954: Sun, New York, J. B. Lippincott Co ., 248 � � �· I PP• E., Landsberg, H. 1960 : Do Tropical Storms Play A Role In The Water Balance o£ the Northern Hemisphere? Journal Geophy-sical j, I Research, 65, 1305-1307 . 2!, 1 ---- . ------· ------�------J 69 --··· Southern California, 31.;.�� pp . .��;op;;!!�=;� McAdie, Alexander G., ;N61903: : Climatology of California. I :-��=��;U. S. Department of Agriculture, Bulletin L, 270 pp . McGurrin, Martin, 1965 : Tropical lones in the Eastern North Pacific, 1964. Pilot Chart ofCyc the North Pacific Ocean, United States Naval Oceanographic Offic e.

Mull, Max W. , 1962 : Tropical Cyclones in the Eastern North Pacific , 1961. Mariners Weather !:£&., 6, 44-46 .

Palmer, Clarence E., c. w. Wi se, 1. J. Stempson, and G. H. Duncan, 1955 : The Practical Aspect � Tropical Meteorology. Bedford, Force Cambridge Research Center, 207 Air PP •

Panofsky, Hans A. , and Glenn W. Brier, 1965 : Some Applications � Statistics to Meteorology, University Park, University of I Pennsylvania, 115 pp. j' Petterssen, SVerre, 19S8 : Introducti.on to Meteorololll• New York, McGraw-Hill Book Co., 327 pp. lI Ramage, c. s., 1959 : Hurricane Development : Journal �Meteorology, 16, 227-237 . 1\ Redfield, w. C., 1857 : On the Cyclones or Typhoons of the North Pacific Ocean; with a Chart, Showing Their Courses of Progression. The American Journal of Science and .Arts, 24, p. 21-38 . ! I Reed, Thomas R., 1932: Weather Types of the Northeast Pacific as Related to the Weather of the North Pacific Coast : Month1y Weather Review, 6o, 246-252. I 1933 : The North American High-Level Anticyclone : Monthly Weather Review, 61, 321-326.

1937 : Further Observations on the North American High Level Ant icyclone : Bulletin --of the --- American Meteorological Society, 18, 297-298.

Riehl, Herbert, 1954: Tropical Meteorology. New York, McGraw-Hill Book Co ., 392 pp.

1965: Introduction to the Atmosphere. New York, McGraw-Hill Book Co., 365pp:--

L__ _ _ ------·-··----·-J 70

·--�· ·- ·------�-----�------·- -··----····· ·-·----�- ··----···-······-- ·----·--·--·------· ---·-· . ------�---·-----·--·-·---·· [ ... ·-·------1 and , Roden, Gunnar I., 19.58 : Oceanographic 11eteorological Aspects of the Gulf of California. Pacific Science, 12, 21-450. I I Rosendal, Hans E. , 1962 : Eastern North Pacific Tropical Cyclones, 1947-1961 : Mariners Weather Log 6, 195-201. (Condensed 1947 -1 961 as Mexican West Tropical G.yclones, Weatherwise, 16, 226-229 .)

Sadler, James C. , 1963 : Tiros Observations of the Summer Circulation � Weather Patterns of the Eastern North Pacific . Honolulu, Hawaii Institute of Geophysics, pp . 47 1964: Tropical Cy:clon s of the Eastern North Pacific as Revealed by Tiros Obs ervations� . Journal -o.f APJ?lied Meteorology, 3, 347 366. P · - 1969 : Personal Connnunication.

Schacht, Elmer J., 1946 : A Mean Hurricane Sounding for the Caribbean Area. Bulletin of �.American Meteorological Society, 27, 324-327 .

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Smithsonian Institution, 1958 : Smithsonian Meteorological Tables. Washington, Smithsonian Institution, pp . 316. Sprague, Malcolm, 1932: Destructive Rains in the Tehachapi !I Mountains , Kern County, California. Climatological Data f2!: � 1 United States £rSections, 19, 80 . '!·

Stearns, Robert D., 196o : Dot - Hawaii 's Third Hurricane : Weatherwise, 13, 146-149 . I

Tannehill, Ivan 1934: The Hurricane . Washington, C., · D. United StatesRey, Department o.f .Agriculture.

1952: Weather .Around � World. Princeton, Princeton University Press, 2nd Ed. 212 pp . I Taylor, George Frederic , 19.54 : Elementary Meteorolog:y:. New York, Prentice-Hall, Inc ., 364 pp .

Thompson, J. C., 19.50 : A Numerical Method for Forecasting Rainfall the .Angeles Area: Monthly Weather Review, 78, 113-124. in Los I l ·------·---·------·-·------·-- L____ _ .JI 71

Tingley, F. G. , 1918 : Tropical Cyclone of September 14-17 , 1918, in the Pacific Ocean Just West of Mexico. Monthly Weather Revi ew, 46, 566-510. Trewartha, Glenn T., 1954: Introduction � Climate. New York, McGraw-Hill Book Co., 402:!!!.. pp .

1962 : The Earth's Problem Climates. Madison, University of WisconSin Press, 334 pp .

Turnage, and T. D. Mallery, 1941 : .Analys is �Rainfall William V. An in Sonoran Desert and Adjacent Territory:. Washington, D. c. Car�negie Institution of Washington, pp . 45 U.S. Department of Connnerce, 196la : Climatological Data, Arizona. (June-November), Washington, D. Department of Connnerce. c., u.s. Department of Commerce, l96lb : Hourly Precipitation Data, U.s. California. (June-November), Washington, D. Department c., u.s. of Commerce.

Department of Commerce, 1962a: Climatological Data, .Arizona• u.s. (June-November), Washington, Department of Commerce. D. c., u.s. U.S. Department of Commerce, 1962b : Hourl;r Precipitation Data, California; (June ...Novembe r) , Washington, D. Department c. , u.s. of Co:mmerce.

U.S. Department of Co:mmerce, 1963a: Climatological Data, Arizona. (June-November) , Washington, D. U.S. Department of Commerce. c., U.S. Department of Commerce, 1963b : Hourly' Precipitation Data, California. (June-November), Washington, D. C., U.S. Department of Commerce. I U.S. Department of Conunerce, 1964a: Climatological Data, Arizona. (June-November) , Washington, U.S. Department of Commerce. I D. c., I U.S. Department of Commerce, 1964b : Hour]Jr Precipitation Data, California. (June-November), Washington, D. U.S. Department of Conunerce. c., I U.S. Department of Coilllllerce, 1965a: Climatological Data, Arizona. (June-November), Washington, D. Department of Cormnerce. I c., u.s. U.S. Department of Commerce, 1965b : HourJ.y Precipitation Data, l California. (June-November), Washington, Department D. c., u.s. of Co ce9 mmer I ------··------______j I 72

Department of Commerce, 1966a: Climatological Data, Arizona. (June-November) , Washington, D. Department of Commerce. ---- c., u.s. U.S. Department of Commerce, 1966b : Hourly Precipitation Data, California. (June-November), Washington, D. U.S. Department ------c. , ;::] of Commerce. I U.S. Department of Commerce, 1967a: Climatological Data, Arizona. (June-November), Washington, D. c., U.S. Department of Commerce. U.S. Department of Commerce, 1967b: Hourly Precipitation Data, California. (June-November), Washington, D. U.S. Department of Co1nmerce. c., U.S. Department of Commerce, 1968 : Weather Bureau Operations Manual. Washington, D. c., U.S. Department of Commerce, 312 pp. Visher, Ste,Phen Sargent, 1922: Tropical Cyclones in the Northeast Pacific, Between Hawaii and Mexico. Monthly Weather Review, 5o, 295-297 . -- _.192 : Some Effects of the Tropical Cyclones of the Pacific. -:-- 3 Annals 2f. Association of .American Geographers, 13, 218 . � -- 1925: Tropical Cyclones 2f. the Pacific . Honolulu, Bernice �� P. Bishop Museum, lbJ pp. Ward, Robert .Allen, 1936: Some Notes on the Squall of August 8th, 1936 in the Los Angeles Area. Bulletin of-- the --- .American Meteorological Society, 17, 329-331. Wenstrom, William Holmes, 1942 : Weather and the Ocean of - .Air. Boston, Houghton Mifflin Co., pp:--- - - 484 . Wilgus, Russell V., 1964: Tropical Cyclones in the Eastern North Pacific, 1963. Pilot North Pacific Ocean, September, U.S. Naval OceChartanograp 2f.hic � Office. Willson, G.H., 1921: San Francisco Forecast District. Monthly Weather Review, 49, 524-525.

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' APPENDIX A I I METEOROLOGICAL ASPECTS OF THE I SEPTEMBER 1939 TROPICAL STORM

Temperature statistics of the pre-storm heat wave and area I weather ob servations during the storm are presented. Temperature

data was obtained through the .Angeles Times; the observations � are those of the Weather Bureau. u.s.

Temperatures:

Sunday September 17, 1939 Min. Max. International .Airport 92 54 CUlver City 69 59 Mt . i'lilson 15 54 Riverside 93 54

Monday, September 18, 1939

International Airport 99 68 CUlver City 96 74 Mt . Wilson 82 66 Riverside 107 65 Los Angeles 100 71

Tuesday, September 19, 1939

Los .Angeles temperatures

83 11.AM 2At"1 102 3PM 95 3.AM 80 11:30 103 92 15 12:00 104.2 5PM4PM 90 54AM.AM 78 1PM 100 6PM 86 9 9 7PM 6AM 1 2PM 1 84

I . . I I ______l .. ______j 13 7h

r------·------··-·---�------·-··--·---· ------1

Ob servations : September 19, 1939 5:00 a.m. I Scattered high clouds, increasing to broken instability Clouds : types during the afternoon: \I I 1. Alto . cumulus at 4:30 a.m. 2. .Alto cumulus cumulus at 12:00 noon. and 3. Alto cumulus and cumulo-nimbus at 4:30 p.m. I Scattered thunderstorms during the afternoon and· evening, occasional thunder lightning observed at and station.

Light thunderstorms 4:50 to 5:50 p.m. Rain: Wind: Northeast the morning, becoming southwest the in in afternoon. I Temp: 104, Min. 5 Max. 1 September 20, 1939

Clouds : Scattered, increasing to broken instability types in I the afternoon:

1 • Alto cumulus at 4:30 a.m. 2. Cumulo-nimbu-s at noon. 3 . Alto c s cumulus in the afternoon. . I umulu and I Scattered thunderstorms during the afternoon and evening .

None. Rain: Wind: Light to gentle Northeast to North the morning in variable in the afternoon.

September 21 , 1939

Scattered clouds, increasing to broken instability Clouds : I types the middle of the in dey": 1. Alto cumulus at 4:30 a.m. 2. Cirrus and at noontime . cumulo -nimbus 3. Cumulus and cumulo-nimbus at 4:30 p.m.

Brilliant lightning seen at sea from Santa Monica. The ! lightning was seen from 1 to 3 a.m. Scattered I thunderstorms at station the afternoon. Intermittenti in light thunder showers 6:33 8:20 p.m. ! to - iI Wind: Light and variable I all dq. ·

______l · ------·-··------····-··------JI . ,

·--··------·-·------· -· 1 September 22, 1939

Clouds : Increasing cirrus and cumulus during the afternoon: I1 1. Clear at 4:30 a.m. 2. Fffii' cirrus and cumulus at noon. 3. Cirrus cumulus at 4:30 p.m. and Lunar halo .

Wind: North to East in the morning and s9uthwest to west in the afternoon.

September 23 , 1939

Clouds : Broken to overcast variable clouds : Cirro-stratus, lowering to alto cumulus and alto stratus in the afternoon.

1 • Cirrus at 4:30 a.m. and a few cirro cumulus . 2. Alto cmnuJ.us and cumulus at noon. 3. Alto stratus and alto cmnulus at 4:30 p.m.

Brilliant solar halo at 7:15 a.m. to 8:15 a.m.

Rain : Light rain from 5:37 p.m. to 5:50 p.m. Wind : Afternoon southwest. winds Temp : Max 101,Min. 77 . September 1939 24, Clouds : Broken intermediate clouds, becoming overcast in the afternoon.

1. Alto stratus and alto cmnulus at 4:30 a.m. 2. to stratus at noon. A1 3. Nimbus stratus at 4:30 p.m.

Rain: Light to moderate by 5 p.m. continuing all night . Wind: Light becoming southeast and increasing suddenly after noon time . velocity of wind 50 miles per hour MaximUill from the southeast at 6:56 p.m. Temp : Max. 81,Min. 65 I I lI ______j ----·------·------·---�------

September 25, 1939

Clouds : Overcast low clouds, breaking somewhat the in

· afternoon.

1 • Nimbus stratus at 4:30 a.m. 2. Alto cumulus and strato cumulus at noon. 3. Strato cumulus at 4:30 p.m.

Moderate from 12 to 1 a.m. becoming heavy at 1 to Rain: 8 a.m. Decreasing until 10:15 a.m. when rain ended. Light rain began again at 5:35 p.m. and continued through midnight . Wind: Easter� fresh wind and then northeast shifting to southwest .

Temp : Max. 76,Min. 62

September 26, 1939

Clouds : clouds becoming broken after 8 a.m. Low 1. Strato-cumulus at 4:30 a.m. 2. .Alto cumulus and cumulus at noon. 3. Strato cumulus at 4:30 p.m.

Light rain ended at 1:15 a.m. Rain: Wind: Light to gentle easter� and southeaster� becoming most� southwest the afternoon. in Temp : Max . 73,Min. 62

_____ L __j l -�------�------·----�--· APPENDIX B ---·--··-1 EASTERN NORTH PACIFIC TROPICAL CYCLONE TRACKS 1961 -1967

Maps containing storm tracks for tropical cyclones occurring

in each month of the tropical cyclone season are presented. All

eastern North Pacific tropical cyclones are classified according to

the month of origin, even if most of the life of the storm occurred

during the follovting month.

The entire track of each tropical cyclone which reached

hurricane intensity is shown by dashed lines; those which onlY

reached tropical storm intensity are shown by solid lines .

For each storm, dates or origin and dissipation are given in

the guide accompanying each monthly map. Each storm is numbered for

ease in map location. One tropical cyclone, Hurricane Sarah, originated to the west of Jj the area mapped and is not shown. I .

·------·----- ·------·- ··----JI

77 · ------�---·-·------·- -·· ······-1 1�- -- . ... ,

MAP B-I . June Storm Tracks

Hurricane Iva 9-10 June 1961 1 2 Hurricane Valerie 24-25 June 1962

3 Hurricane Erni1Jr 28-30 June 1963

4 Tropical Storm Victoria 3-7 June 1965

5 Tropical Storm Wallie 16-1 8 June 1965

6 Tropical Storm Ava 28 June-5 Jucy 1965

Tropical Storm Bernice 30 · June-8 July 1965 7 8 Hurricane Adele 20-24 June 1966

9 Tropical Storirl Agatha 7-10 June 1967

10 Tropical Storm Bridget 16 June 1967

11 Hurricane Carlotta 22-26 June 1967

------�-� ------�----·� -- �------�-- · ____ j

------, I I I

MAP B-II. July Storm Tracks I

- 1 Tropical Storm Joanne 10-1 2 July 1961

2 Tropical Storm Kathleen 14-16 July 1961

3 Tropical Storm Liza 14-1 9 July 1961

4 Tropical Storm Madeline 19-20 July 1961

5 Tropical Storm Willa 7-10 July 1962

6 Hurricane Florence 14-1 7 July 1963

7 Hurricane Glenda 19-21 July 1963

8 Tropical Storm Natalie 5-1 July 1964

9 Hurricane Odessa 15-1 8 July 1964

10 Tropical Storm Prudence 20-24 July 1964

11 Tropical Storm Denise 5-15 July 1967

12 Tropical Storm Eleanor 13-15 July 1967

13 Tropical Storm Francene 23-27 July 1967

14 Tropical Storm Georgette 25-30 July 1967

IL ______j I I -� '\, 9. ;.jj/ V I

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B-III. Aug ust Storm rt-acks MAP I I 1 Tropical Storm Naomi 3-5 August 1961

2 Tropical Storm Ava 16-20 August 1962

20-22 August 1962 3 Tropical Storm (Unnamed) 4 Tropical Storm Ros� 20-22 August 1964

I 5 Tropical Storm Sylvia 23-24 August 1964

6 Tropical Storm Claudia 7-1 0 August 1965 I I I 7 Tropical Storm Doreen 20-31 August 1965 I 8 Hurricane 29 August-4 September 1965 I Dnily ! I 9 Hurricane Blanca 2-1 2 August 1966 10 Hurricane Connie 7-1 7 August 1966 I 11 Hurricane Dolores 16-26 August 1966 I 12 Hurricane Eileen 23-29 August 1966 I 13 Tropical Storm 9-10 August 1967 Hilary I 14 Tropical Storm llsa 11-17 August 1967

15 Hurricane Jewel 17-21 August 1967 I

iI 16 Hurricane Katrina 29 August-2 September 1967 1 I

L,I ______j . a:e.

··----·· --· ---·------·------····------·------. ------1 r -~ 0 'In "IS ~ r 'l. ~J 1\, I IT I I cr I ! i I i \ I I ! I I I I I OQ I .., j G(\ "' ! j I '\p I ~ - ~ v ~ ,/'d) ~ '-"'.~ lr- 00 _,1 , '!! / vl!ll \ 00 _. V:L fl.) ~· J ,..!>.1 ~,) ~ Flf{' ljj t\ ,, ~ lC ~ j!/Jv ~.a 0 ~'~ -· +"i --v- , - {/) co+""' +"i ~~~ VJ fl.) v ~r?J j ;' ~ D() "o LlJ - . - 1/ -J, ~~ !, H J I H .· ~,/ H I I 0 ~ ,_1' I 1 1/ ,' I I _\,a I J -~- ~ ~ J ~ ~ , I I I ) 'J ~;!, I !)!"' .... .,,., I •o 1--..... v ·s I I ' - I - I I I I I I V: I I ~ ! . 'In --1 J r I ~~ - I '\ rJ I I J I I I • -I I I I I I f I I ".o ' I 00 I -1\\ '\ I f 0 'L ' I - I I I L______I ------______! l r I MAP B-IV. September Storm Tracks I I I 1 Tropical Storm Orla 6-11 September 1961 2 Tropical Storm Bernice 1-6 September 1962 3 Tropical Storm Claudia 20-24 September 1962 4 Tropical Storm (Unnamed) 26-30 September 1962 5 Tropical Storm Irah 12-14 September 1963 6 Tropical Storm Jenni..fer 12-15 September 1963

7 Tropical Storm Katherine 12-15 September 1963 8 Tropical Storm. Lillian 24-28 September 1963

9 Tropical Storm Tillie 7-9 September 1964 10 Tropical Storm Florence 7-15 September 1965 11 Tropical Storm. Glenda 13-22 September 1965 12 Tropical Storm Hazel 23-26 September 1965

13 Hurricane F.rancesca 5-16 September 1966 14 Tropical Storm. Gretchen 7-11 September 1966 15 Hurricane Helga 9-15 September 1966 16 Tropical Storm Ione 10-14 September 1966 17 Tropical Storm Joyce 14-20 September 1966 18 Tropical Storm Kirsten 25-29 September 1966

19 Hurricane Lily 5-11 September 1967 20 Hurricane Sarah (not shown) 8-22 September 1967 21 Tropical Storm Monica 13-20 September 1967 I 22 Tropical Storm Nanette 13-21 Septemb~ 1967~---J 8$

olll 'Ill.. I r-f ~ - I ( ::: 00 \ ] \ ~ I ?1 I ~ I 0 ~ ~ ~ ~ "o w CQ

:>. 2:: 1 ~ • 111 ~ ;· 86

,------· ------

1 i

MAP B-V. October Storm Tracks

1 Tropical Storm Pauline 2-4 October 1961 2 Tropical Storm Rebecca 3-4 October 1961 3 Hurricane Doreen 1-4 October 1962 4 Hurricane 11ona 17-18 October 1963 5 Tropical Storm Lorraine 4-5 October 1966 6 Tropical Storm Maggie 16-19 October 1966 7 Hurricane Olivia 5-14 October 1967 8 Hurricane Priscilla 13-20 October 1967 9 Tropical Storm Ramona 20-25 October 1967

I L ______------. ~I lX4i ~~ I ! I I I

I I i ! I I ! ! I I l I I I

IL.___ ---- ___ j

/ 88

[------·------·------·-,------··

MAP B-VI . November Storm Tracks

1 Tropical Storm Simone 1-2 November 1961

2 Hurricane Tara 11-12 November 1961

i I I I I I I I I I .

·------··--· ------·-----·-·------_____ - j 89.

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