WEATHER BUREAU Western Region Salt Lake City, Utah August 1969 Analysis of the Southern California Santa Ana of January 15-17, 1966 BARRY B. ARONOVITCH 8 Technical Memorandum WBTM WR-42 \.U.S. DEPARTMENT OF COMMERCE I ENVIRONMENTAL SCIENCE SERVICES ADMINISTRATION~ '----~----~---~-~ ---~-~--------------------- WESTERN REGION TECHNICAL MEMORANDA The Technical Memorandum series provide an informal medium for the documentation and quick dissemination of results not appropriate, or not yet ready, for formal publica­ tion in the standard journals. The series are used to report on work in progress, to describe technical procedures and practices, or to report to a limited audience. These Technical Memoranda will report on investigations devoted primarily to Regional and local problems of interest mainly to Western Region personnel, and hence will not be widely distributed. These Memoranda are available from the Western Region Headquarters at the following address: Weather Bureau Western .Region Headquarters, Attention SSD, P. 0. Box 11188, Federal Building, Salt Lake City, Utah 84111. The Western Region subseries of ESSA Technical Memoranda, beginning with No. 24, are available also from the Clearinghouse for Federal Scientific and Technical Informa­ tion, U. S. Department of Commerce, Sills Building, Port Royal Road, Springfield, Virginia 22151. Price $3.00. Western Region Technical Memoranda: No. 1* Some Notes on Probability Forecasting. Edward D. Diemer. September 1965. No. 2 Climatological Precipitation Probabilities. Compiled by Lucianne Miller. December 1965. No. 3 Western Region Pre- and Post-FP-3 Program. Edward D. Diemer. March 1966. No. 4 Use of Meteorological Satellite Data. March 1966. No. 5** Station Descriptions of Local Effects on Synoptic Weather Patterns. Philip Williams. April 1966. No. 6 Improvement of Forecast Wording and Format. C. L. Glenn. May 1966. No. 7 Final Report on Precipitation Probability Test Programs. Edward D. Diemer. May 1966. No. 8 Interpreting the RAREP. Herbert P. Benner. May 1966. (Revised Jan. 1967.) No. 9 A Collection of Papers Related to the 1966 NMC Primitive-Equation Model. June 1966. No. 10* Sonic Boom. Loren Crow (6th Weather Wing, USAF, Pamphlet). June 1966. No. 11 Some Electrical Processes in the Atmosphere. J. Latham. June 1966. No. 12* A Comparison of Fog Incidence at Missoula, Montana, with Surrounding Locations. Richard A. Dightman. August 1966. No. 13 A Collection of Technical Attachments on the 1966 NMC Primitive-Equation Model. Leonard W. Snellman. August 1966. No. 14 Applications of Net Radiometer Measurements to Short-Range Fog and Stratus Forecasting at Los Angeles. Frederick Thomas. September 1966. No. 15 The Use of the Mean as an Estimate of "Normal" Precipitation in an Arid Region. Paul C. Kangieser. November 1966. No. 16 Some Notes on Acclimatization in Man. Edited by Leonard W. Snellman. Nov. 1966. No. 17 A Digitalized Summary of Radar Echoes Within 100 Miles of Sacramento, California. J. A. Youngberg and L. B. Overaas. December 1966. No. 18 Limitations of Selected Meteorological Data. December 1966. No. 19 A Grid Method for Estimating Precipitation Amounts ·by Using the WSR-57 Radar. R. Granger. December 1966. No. 20 Transmitting Radar Echo Locations to Local Fire Control Agencies for Lightning Fire Detection. Robert R. Peterson. March 1967. No. 21 An Objective Aid for Forecasting the End of East Winds in the Columbia Gorge. D. John Coparanis. April 1967. No. 22 Derivation of Radar Horizons in Mountainous Terrain. Roger G. Pappas. April 1967. No. 23 "K" Chart Application to Thunderstorm Forecasts Over the Western United States. Richard E. Hambidge. May 1967. *Out of Print **Revised A western Indian symbol for rain. It also symbolizes man's· dependence on weather and environment in the West. U. S. DEPARTMENT OF COMMERCE ENVIRONMENTAL SCIENCE SERVICES ADMINISTRATION WEATHER BUREAU Weather Bureau Technical Memorandum WR-42 ANALYSIS OF THE SOUTHERN CALIFORNIA SANTA ANA OF JANUARY 15 - 17, 1966 WESTERN REGION TECHNICAL MEMORANDUM NO. 42 SALT LAKE CITY, UTAH AUGUST 1969 TABLE OF CONTENTS Page List of Figures iii, iv Abstract 1 Introduction 2 Meteorology - Low-Level Features 2 500-Mb Discussion 5 Radar Scope Discussion 6 Issuance of Warnings 7 Storm Damage 8 Conclusions 8 Acknowledgments 9 References 9 Appendix - Dynamics 10 i i LIST OF FIGURES Figure 1 Map of Southern California Showing Normal Catalina Radar Ground Clutter Pattern 11 Figure 2 Graph of Sea-Level Pressure at Santa Catalina, 12 January 14 - 18, 1966 Figure 3 NMC Surface Analysis OOOOZ January 15, 1966 13 Figure 4 NMC Surface Analysis OOOOZ January 16, 1966 14 Figure 5 NMC Surface Analysis 1800Z January 16, 1966 15 Figure 6 NMC Surface Analysis 0600Z January 17, 1966 16 Figure 7 NMC Surface Analysis 0900Z January 17, 1966 17 Figure 8 Difference in Sea-Level Pressure lAX - SFO and 18 LAX-TPH. 850-700 mb Thickness for LAS and SAN, January 13 - 18, 1966 figure 9 San Diego Radiosonde Observations, January 15 - 19 16, 1966 Figure 10 Sandberg Dewpoint, Sandberg, El Taro, and 20 Pa.Lmdale Wind Speeds, January 15 - 16, 1966 Figure 11 500-mb Analysis - 1200Z, January 14, 1966 21 Figure 12 500-mb Analysis - 1200Z, January 15, 1966 22 Figure 13 500-mb Analysis - 1200Z, January 16, 1966 23 Figure 14 500-mb Analysis- OOOOZ, January 17, 1966 24 Figure 15 500-mb Analysis- 1200Z, January 17, 1966 25 Figure 16 500-mb Isotherms and Jet Stream - OOOOZ, 26 January 15, 1966 Figure 17 Isotherms and Jet Stream - 1200Z, 27 January 15, 1966 Figure 18 500-mb Isotherms and Jet Stream- OOOOZ, 28 January 16, 1966 Figure 19 500-mb Isotherms and Jet Stream- 1200Z, 29 January 16, 1966 Figure 20 500-mb Isotherms and Jet Stream- OOOOZ, 30 January 17, 1966 iii Page Figure 21 500-mb Barotropic Vorticity 12002, 31 January 16, 1966 Figure 22 Catalina Radar, 1916 PST, January 16, 1966 32 Figure 23 Catalina Radar, 1938 PST, January 16, 1966 '33 Figure 24 Catalina Radar, 1948 PST, January 16, 1966 34 Figure 25 Catalina Radar, 1959 PST, January 16, 1966 35 Figure 26 Catalina Radar, 2015 PST, January 16, 1966 36 iv ANALYSIS OF THE SOUTHERN CALIFORNIA SANTA ANA OF JANUARY 15-17 ~ :!.966 By Barry B. Aronovitch U.S. Weather Bureau Airport Station Santa Catalina Island California * ABSTRACT A meteorological analysis of conditions during the severe Santa Ana of January 15. - 17, 1966 is given, with emphasis on the 500-mb flow. The gradient-wind equation defines the maximum contour curvature which a parcel of air can follow dynamically for a given wind speed. If this maximum is exceeded, the parcel trajectory may become anti­ cyclonic. This condition is related to the so-called "wet" Santa Ana. *Author presently associated with Fire-Weather Office, Olympia, Washington. - 1 - ANALYSIS OF THE SOUTHERN CALIFORNIA SANTA ANA OF JANUARY 15 - 17, 1966 I. INTRODUCTION On January 15, 1966, a violent Santa Ana windstorm unleashed its force upon the harbor city of Avalon, Santa Catalina Island, California. Twenty boats ranging from 18-foot outboards to 65-foot pleasure cruisers were damaged by this storm. Of these, 16 were completely demolished. The four remaining vessels were beached and suffered minor, moderate, or major damage. Ten persons were rescued from various vessels. Ten others were admitted to the hospital for treat­ ment. One person was drowned. One hundred sixty feet of pier and twenty-six feet of 12-inch-thick seawall were washed away by the storm. ~ieces of the seawall were found more than 150 feet from point of origin. Three buildings and many feet of brick walk sustained damage from this storm, along with much sea-water damage at the Catalina Art Gallery and Museum located at Casino Point. Total damage was estimated to exceed $300,000. A meteorological analysis of this devastating storm showed that it differed considerably from the usual Santa Ana. Radar was particu­ larly helpful in issuance of short-term warnings. II. METEOROL03Y - LOW LEVEL FEATURES The strong easterly winds which occurred in parts of southern Cali­ fornia during January 15 - 17, 1966, were not the usual breed of Santa Ana winds which blow during fall and winter months. By 0400PST, January 14, a Los Angeles Forecast Center objective aid indicated a Santa Ana windstorm was imminent. This aid is based primarily on the presence of a rather strong west-to-east height gradient at the 500-mb level, coincident with a large surface pressure gradient between the Oregon coast and eastern Nevada. A third factor is a significant 500-mb temperature gradient between eastern Washington and eastern Nevada. Values of the above parameters on January 14 and January 15 are shown in Table 1 belowo The possibility of a Santa Ana windstorm is listed as a percentage probability in the last column. TABLE I 500-mb ht diff. Sea-Level Press. Temp diff. 500-mb Obj Sys. OAK-ELY diff. GEG-ELY (°C) Santa Ana Hour/Day (tens of GDM) MFR-ELY (mb) prob. (%) 04P 1/14 +7 +6.2 -9 18 16P +10 +7.1 -6 20 04P 1/15 +16 +11. 7 -2 50 16P +21 +7.6 -9 70 - 2 - A Santa Ana generally occurs after a 24-hour lag when large-scale features, as shown in the table, exist. However, the typical Santa Ana of sunny skies, low humidities, and strong northeast winds over particular mountain ridges did not develop. Primarily, the winds were accompanied by cloudiness and rainshowers. Secondly, the winds blew in unusual locations. Generally, they swoop down through the main passes of the coastal ranges, such as the Santa Clara Valley, the canyons of the Newhall and Saugus areas, and Cajon Pass (Figure 1). This time, however, the wind was not primarily guided by these usual terrain features, but by others. This wind behavior will be discussed in greater detail later in the paper.