NOAA TM NOS LSCD 1

f f JOAA Technical Memorandum NOS LSCD 1

U. S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration

GREAT LAKES ICE COVER WINTER 1968-69

LAKE

SURVEY MARINE and earth CENTER SCIENCES LIPPARY

&CT 2 1973 Federal Building, Detroit, Mich. U~ S~ PeP'- Com:

October 1971 £6 /7?f.y

U. S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration 1 National Ocean Survey

NOAA Technical Memorandum NOS LSCD 1

GREAT LAKES ICE COVER

WINTER 1968-69

Donald R. Rondy

f

Lake Survey Center Limnology Division, Federal Building Detroit, Michigan

October 1971 (3 5618 CONTENTS

Page

LIST OF TABLES AND FIGURES iii

ABSTRACT 1

INTRODUCTION i

DATA COLLECTION

Aerial Observations 2

Shore Observations 2

Freezing Degree-days 2

WINTER CHARACTERISTICS 3

DATA PRESENTATION

Ice Charts 4

Ice Summary Charts 4

DISCUSSION

Lake Superior 5

Lake Michigan 6

Lake Huron 8

Lake St. Clair 9

Lake Erie 10

Lake Ontario 11

ACKNOWLEDGEMENTS 12

ii LIST OF TABLE AND PLATES

TABLE

1 Key to Ice Chart Symbols

PLATES

1 Accumulated Freezing Degree-days--Lake Superior

2 Accumulated Freezing Degree-days--Lake Michigan

3 Accumulated Freezing Degree-days--Lake Huron

4 Accumulated Freezing Degree-days--Lake Erie

5 Accumulated Freezing Degree-days--Lake Ontario

6 Maximum Ice Cover-Southern Lakes

7 Maximum Ice Cover-Northern Lakes

8 Breakup Patterns

9-11 Ice Charts--Lake Superior

12-16 Ice Charts--Whitefish Bay

17-19 Ice Charts--St. Marys River

20-22 Ice Charts--Straits of Mackinac

23-24 Ice Charts--Lake Michigan

25 Ice Chart--Lake Huron

26-28 Ice Charts--Lake St. Clair

29-31 Ice Charts--Lake Erie

iii GREAT LAKES ICE COVER WINTER 1968-69

Donald R. Rondy

Department of Commerce NOAA, National Ocean Survey Lake Survey Center Detroit, Michigan

ABSTRACT

Twenty-three ice charts were produced from data collected on eight reconnaissance flights made during the 1968-69 winter ice season. Ice formation was first reported on December 9, 1968. Areas reporting extended from Duluth, Minnesota, on western Lake Super­ ior, to Barcelona, New York, on the south shore of Lake Erie. Winter temperatures generally varied from slightly above normal in the Lake Superior region to slightly below normal on Lake Erie. During the period of maximum ice cover, 40 percent of the surface of Lake Superior was covered. More than half the ice was concentrated in the Apostle Islands-Duluth-Isle Royale areas at the western end of the lake. Lake Michigan was 15 percent covered with the ice confined mostly to the north end of the lake and Green Bay. Lake Huron contained a maximum 50 percent ice cover with winter ice in the North Channel, the Straits of Mackinac, and Saginaw Bay. Lake Erie was 80 percent ice covered, with heavy winter ice concentrated along the southern and eastern shores. The mid-lake area contained brash and small floes. At maximum, Lake Ontario was estimated to be 10 percent covered, with the ice concentrated in the northeastern end of the lake. The last report of ice in the Great Lakes was from the Buffalo area of Lake Erie on May 2, 1969.

INTRODUCTION

The aerial ice reconnaissance program of the Lake Survey Center began in 1963. It is part of a total plan to obtain data on the physical pheno­ mena of the Great Lakes. The purpose of the ice program is to gain an un­ derstanding of the formation, distribution, and decay of the ice cover on the Great Lakes and their connecting waters. The data are presented in the form of ice charts covering the individual lakes and specific areas on those lakes. Accumulations of freezing degree-days were used as an index to determine the severity of the winter and to aid in scheduling the re­ connaissance flights. As the ice season progressed U. S. Coast Guard ice messages and reports made by Lake Survey Center water level gage observers were also used as flight scheduling aids.

This report presents data collected during the 1968-69 visual aerial ice reconnaissance program and summarizes the winter ice and weather condi­ tions for the season. Ice cover reports have been prepared for each winter since 1962-63 and are available from the Lake Survey Center.

1 DATA COLLECTION

Aerial Observations

Ice cover characteristics were charted in symbolic form from U. S. Coast Guard aircraft flying at altitudes of up to 9000 feet (2740 m). Ice information was plotted on work sheets, while detailed verbal descriptions were recorded on magnetic tape to aid the observer in a later compilation of the ice charts. The flights began on February 4, 1969, and continued at weekly intervals through April 3, 1969. Approximately 6200 miles (9900 km) and 40 hours of flight time were logged during the season. The dates of the reconnaissance flights and the areas covered are given below.

ICE RECONNAISSANCE FLIGHTS - WINTER 1968-69

FLIGHT DATE AREA COVERED

1 February 4, 1969 Lakes St. Clair, Erie

2 February 13 Straits of Mackinac Area, Lake Superior

3 February 25 Lakes St. Clair, Erie

4 March 4 Straits of Mackinac Area, Whitefish Bay, Lakes Huron, St. Clair

5 March 11 Straits of Mackinac Area Lake Superior

6 March 22 Lakes St. Clair, Erie

7 March 27 Straits of Mackinac Area, Lake Superior

8 April 3 Straits of Mackinac Area, Whitefish Bay

Shore Observations

Lake Survey water level gage observers reported daily ice conditions throughout the winter. This information was used to monitor ice conditions and to locate general areas where ice first formed and where it was last to leave.

Freezing Degree-days

The accumulation of freezing degree-days is a commonly used index of

2 winter severity. A freezing degree-day is defined as a day with mean temperature one degree below 32°F (0°C). For example, a day having a mean temperature of 27°F (-3°C) would equal five freezing degree-days. Many other limnological and meteorological factors affect ice formation and growth, however certain relationships have been established between freezing degree-days and ice cover distribution. The daily mean air temperature from six National Weather Service meteorological stations on the Great Lakes were used to determine the accumulation of freezing degree- days for each lake. The stations used v/ere Duluth, Minnesota; Sault Ste. Marie, Michigan; Green Bay, Wisconsin; Alpena, Michigan; Cleveland, Ohio; and Rochester, New York. Graphs of accumulated freezing degree-days ver­ sus time were plotted for each of the stations (Plates 1 through 5). The curve of the long-term mean is shown so that determinations can be made of relative winter severity, and the approximate date of maximum degree-day accumulation, and the approximate date of maximum ice cover. The greatest areal extent of ice cover seems to occur just prior to the maximum freezing degree-day accumulation.

The flight dates and the accumulated freezing degree days for the per­ iod November through April are shown on Plates 1 through 5. Temperature data were obtained from the Weekly Weather and Crop Bulletin published by the U. S. Department of Commerce.

WINTER CHARACTERISTICS

The 1968-69 winter temperature patterns varied from slightly above normal in the north to slightly below normal in the south. Temperatures for Lake Superior and northern Lake Michigan were above normal, as shown by the low accumulation of freezing degree-days recorded at Sault Ste. Marie and Green Bay (Plates 1 and 2). Temperatures for Lakes Huron and Erie were below normal, as shown by the relatively large accumulation of freezing degree-days recorded at Alpena and Cleveland (Plates 3 and 4). The freezing degree-day curve for Rochester, however, appeared to follow the long-term mean (Plate 5). The early winter period also saw a number of meteorological stations record their greatest snowfall.

Temperatures for November and the first part of December were generally above normal across the Great Lakes area. The temperatures for the whole month of December, however, generally averaged 2°F below normal. The low monthly temperature was the result of persistent and extremely low daily temperatures during the last two weeks of the month. By the week ending December 29, temperatures had dropped to as much as 8°F below the normal of 12°F (-11°C) at Duluth, and 10°F below the normal of 18°F (-8°C) at Sault Ste. Marie. December also brought heavy snowfall to parts of Minne­ sota, Wisconsin, and upper Michigan. Green Bay, Wisconsin, reported 26.7 inches (67.8 cm) of snowfall, highest since 1887; Alpena, Michigan, 35.2 inches (89.4 cm), highest in 81 years and second highest on record; and Marquette, Michigan, 41.1 inches (104.4 cm), the heaviest in 58 years. Low temperatures during the last two weeks of December are indicated by the steep upward slope of the freezing degree-day curves for all of the

3 stations (Plates 1 through 5). Low temperatures continued into January, and for the week ending January 5, ranged from -7°F (~22°C) at Duluth, Minnesota, to 16°F (-9°C) at Cleveland, Ohio.

Cold weather predominated during the first half of January. Warmer weather prevailed during the last half, causing temperatures for the month to range from normal in the northern half of the basin to 2°F below normal in the southern half. January snowfall was the highlight of the month with Duluth, Minnesota accumulating 46.8 inches (118.9 cm) of snow, great­ est for any month since 1917; and Marquette, Michigan, with a snowfall of 29.5 inches (74.9 cm) the fourth heaviest in 40 years. February temp­ eratures averaged 3° above normal across the Great Lakes with precipitation at record lows. Green Bay, Wisconsin, recorded the lightest snowfall in 82 years; Milwaukee, Wisconsin, lightest in 85 years; Alpena, Michigan, recorded 0.34 inches (0.86 cm), the lowest on record; Detroit, Michigan, lowest in 98 years; and Buffalo, New York, lowest in 99 years. During the first two weeks of March, temperatures ranged from 3° to 6°F below normal. Temperatures for the week ending March 23 (the third week) ranged from 32°F (0°C) at Duluth to 47°F (8°C) at Cleveland. However, at the end of March, only Cleveland and Rochester reported temperatures above freezing. Temperatures for the month were near normal, ranging from 21°F (-6°C) at Duluth to 35°F (2°C) at Cleveland. During the first week in April, only Duluth and Sault Ste. Marie reported temperatures below freezing, and by April 13, all stations were reporting temperatures in the 40's (°F).

DATA PRESENTATION

Ice Charts

The eight ice reconnaissance flights made during the season resulted in the publication and distribution of 23 ice charts. Ice data on the charts is shown in symbol form. The symbols show principal ice characteristics such as boundaries, concentrations, ages, types, topography, and limits of observed areas (Table 1). With the exception of Lake Ontario, ice charts were prepared for all of the lakes including Lake St. Clair. Supplementary charts of Whitefish Bay, St. Marys River, and the Straits of Mackinac were included to show the ice cover of these critical areas in more detail.

Ice Summary Charts

Summary charts were prepared from information obtained on Lake Survey Center flights, reports from shore observers, Canadian Department of Trans­ port, and U. S. Coast Guard messages. The charts show the periods of maxi­ mum ice cover on the lakes and the distribution of ice during the breakup period. Plate 6 shows the ice distribution during the period of estimated maximum cover on the southern lakes. Plate 7 shows the ice distribution on the northern lakes at its estimated maximum and Plate 8 shows the break­ up patterns and ice cover distribution across the five Great Lakes.

4 DISCUSSION

Lake Superior

Flights over Lake Superior covered the American shore from Sault Ste. Marie, Michigan, to Duluth, Minnesota, and the north shore from Duluth to Isle Royale. They were made on February 13, March 11, and 27, 1969. Sup­ plementary flights were made over Whitefish Bay on March 4, and April 3. The March 4 flight included the St. Marys River. The five flights result­ ed in the publication of 11 ice charts; three of Lake Superior, five of Whitefish Bay, and three of St. Marys River (Plates 9 through 19). The dates of the Superior flights are also indicated on the freezing degree-day graphs for Duluth and Sault Ste. Marie (Plate 1).

First ice on Lake Superior was reported by the water level gage ob­ server at Point Iroquois on December 9. On December 10 Whitefish Point reported ice in the harbor. The Keweenaw Waterway was reported to have 7-tenths concentration of drifting floes on December 13. Duluth Harbor did not report ice until December 15. On December 16 ice in shallow Che- quamegon Bay halted a lake freighter, which required Coast Guard assistance to make Ashland Harbor. Ice was not reported in the upper St. Marys River until December 26. The comparatively late reports of first-ice were pri­ marily due to above normal temperatures during November and early December. The temperatures are shown on the freezing degree-day graphs as normal to below normal accumulations for this period (Plate 1). The last half of December was quite cold. The low temperatures are indicated by the great­ er than normal freezing degree-day accumulations for both Duluth and Sault Ste. Marie (Plate 1). Extensive ice cover along the south shore of Lake Superior from Sault Ste. Marie to Duluth was reported during the first part of January. The Soo locks were officially closed on January 5, be­ cause of ice in the lower St. Marys River. The above normal freezing de­ gree day accumulations of late December continued through January creating conditions for extensive ice formation.

From observations made on the first flight (February 13), Lake Super­ ior was estimated to be 30 percent ice covered. Winter ice composed the cover in the Whitefish Bay, Keweenaw Bay, Apostle Islands, and Duluth areas. A band of young ice, about 10 miles (16 km) wide, was located along the north shore between Little Two Harbors and Grand Portage. Thunder and Black Bays, and the area on the north side of Isle Royale, contained heavy concentrations of winter ice. Various concentrations of drifting brash and cake ice were observed in the lake beyond the winter ice cover.

The last two weeks of February were somewhat warmer than the first two weeks, as indicated by the flattening of the degree-day curves (Plate 1). The first two weeks of March, however, were much colder, as indicated by the sharp upward climb of the curves.

The second Lake Superior flight took place on March 11, 26 days after the first flight. The temperatures during this 26-day period were not con-

5 ducive to extensive ice formation and on March 11 the lake was estimated to be 40 percent ice covered an increase of only 10 percent.

Minimum ice growth was seen generally in the eastern half of the lake. A considerable increase in areal coverage was seen in thewestern portion, north of a line running from Outer Island (in the Apostle Islands) to the vicinity of Rock Harbor Light on Isle Royale. The cover consisted of young ice, ice rind, and brash concentrations ranging from 5 to 9-tenths. The cover north of Isle Royale was solid winter ice and extended to the east on St. Ignace Island on the Canadian shore. The area from the Kewee­ naw Peninsula to Marquette contained large areas of young ice brash of 9- tenths concentration. At the entrance to Whitefish Bay, the ice edge ex­ tended to the west from Coppermine Point then south to Crisp Point. The ice was composed of a mixture of brash and small to medium size floes of both young and winter ice.

The lake ice was separated from the bay ice along a prominent line extending from Corbeil Point, on the Canadian side, to Whitefish Point. The bay ice was winter ice with a drifted snow cover, containing heavy rafting and numerous jammed areas.

The last flight took place on March 27. At that time an estimated 10 percent of the lake was ice covered. It was generally confined to the south shore with very little ice observed in the mid-lake areas. The Apostle Islands area, Keweenaw Bay, the Munising area, and Whitefish Bay were the only areas along the south shore containing an appreciable ice cover. The first commercial ship passed upbound through the MacArthur Lock on April 4, opening Lake Superior to inter-lake shipping. Ice was still reported at the eastern end of the lake in the vicinity of Point Iroquois on April 28.

Lake Michigan

Flights were made over the northern portion of Lake Michigan on Feb­ ruary 13, March 4, 11, 27, and April 3, 1969. Plates 20, 21, and 22 show ice conditions in northern Lake Michigan and the Straits of Mackinac. Plates 23 and 24 show ice conditions in northern Lake Michigan only. No extensive ice cover was reported in the southern half of the lake, there­ fore, no flights were made over that area.

Extensive ice formation was reported on December 7 and 8 in southern Green Bay. Harbor ice was reported at Port Inland on December 8 and at Milwaukee on December 21. During the last part of December, shore ice was reported along the entire lake perimeter. The low temperatures are shown by the steep upward slope of the Green Bay freezing degree-day curve (Plate 2). Wind and nearshore drift ice combined to create shipping problems in the Grand Haven area. Two tankers required Coast Guard assistance to enter the harbor through 8 to 10-foot (2 to 3 m) high windrows.

The first Lake Michigan reconnaissance flight, February 13, covered Green Bay and the northern portion of the lake. The bay was covered by a

6 winter ice sheet but the entrance channels to the bay were open. In the lake east of Washington Island, areas of brash having 3-tenths concentra­ tion were observed extending 10 to 15 miles (16 to 24 km) out from shore. Grand Traverse Bay contained areas of consolidated brash in the southern ends of the east and west arms. Winter ice covered Little Traverse Bay, Sturgeon Bay, and the area north of a line from Waugoshance Point to Gar­ den Island. A large area of winter ice extended south of this line to the vicinity of Charlevoix. It was composed of a 7 to 8-tenths concentration of brash and small to medium size floes. No ice was observed in the nor­ thern mid-lake area. Large areas of drift ice were reported along the eastern shore from Frankfort to Holland. Areas of drift ice at 8-tenths concentration were reported in the lake off Michigan City. A mile wide band of drifting ice was also reported in the lake off Chicago Harbor. Very little ice was reported along the west shore between Waukegan and Two Rivers. The lake, including Green Bay, was estimated to be 15 percent ice covered at this time.

February temperatures were generally above normal as indicated by the freezing degree-day curve for Green Bay (Plate 2). By the week of March 11, Green Bay was nearly 100 accumulated freezing degree-days below the mean. The reconnaissance flight on March 11 showed Green Bay containing winter ice with a heavy snow cover. In some areas the snow cover appeared to have been melted and refrozen. The ice edge in the Straits extended east and south from Seul Choix Point (near Port Inland) to High Island, then to Beaver, Garden, and Hog Islands, and then southeast to the vicinity of Good Hart. The area was composed of a 10-tenths concentration of winter ice with a drifted snow cover and medium to heavy windrows in the Straits. Bordering the ice edge were various concentrations of brash, young ice, and ice rind. Adjacent to Beaver Island, and extending to the southeast, was a large area of brash of approximately 2-tenths concentration. Ice extended out of Little Traverse Bay as far as a line running from Good Hart to Charlevoix. Ice in the West Arm of Grand Traverse Bay extended out to a line between Old Mission Point and Peshawbestown. The East Arm of Grand Traverse Bay was covered by ice extending to the vicinity of Elk Rapids. Very little ice was reported in the southern portion of the lake. The small amounts of shore and drift ice present appeared to be confined to the area between South Haven-Benton Harbor and Chicago Harbor.

Shortly after March 11 temperatures rose above the freezing point, causing deterioration and a redistribution of the ice cover. The warm spell is indicated by the downward slope of the degree-day curve for the week ending March 16 (Plate 2). The ice sheet did not recover from this mild weather, even though temperatures subsequently dropped below freez­ ing. Available information indicated that the greatest areal extent of the ice cover occurred during the week ending March 16, and covered an estimated 15 percent of the lake surface. The degree-day curve began a downward trend during the last week in March, signaling the start of the breakup period. At that time a lake freighter, led by a Coast Guard ice breaker, passed through the Straits of Mackinac. By April 3, ice had di­ minished to cover an estimated 10 percent of the lake. At that time ice in Green Bay was confined to an area south of Chambers Island and to the

7 Bays de Noc. Between those areas were large expanses of open water and ex­ tensive areas of drifting brash. The ice edge in the Straits area extend­ ed from Point Patterson to the vicinity of White Shoal Light, then south to the Good Hart area. Most of that ice was composed of 7 to 9-tenths con­ centration of brash and small to medium size floes. Solid winter ice was found in Sturgeon Bay and east of a line extending from Waugoshance Point to Brevort. Large areas of winter ice were present in Little Traverse Bay and in the extreme southern ends of Grand Traverse Bay. Ice was last re­ ported on April 9 by the water level gage observer at Port Inland.

Lake Huron

Four reconnaissance flights were made over portions of Lake Huron dur­ ing the 1968-69 ice season. Data from three of these flights were incor­ porated into ice charts of the Straits of Mackinac (Plates 20,21, and 22). One Lake Huron ice chart resulted from observations made on March 4 (Plate 25), and that date is indicated on the freezing degree-day graph for Al­ pena (Plate 3). Only the northern and United States portions of the lake were observed by Lake Survey Center personnel.

First ice in Lake Huron was reported on December 15 at both Mackinaw City in the north and at Lakeport in the south. On December 18 approxi­ mately 2 inches (5 cm) of ice were reported on Saginaw Bay. On January 3 a lake freighter required Coast Guard assistance to pass through concen­ trations of brash and floes at the entrance to the St. Clair River. On January 5 the Straits of Mackinac were reported ice covered. The freezing degree-day accumulations for Alpena (Plate 3) were above normal for Decem­ ber and January, indicating good ice forming conditions.

The first flight over Lake Huron took place on February 13, covering the northern end of the lake and a portion of the North Channel. The winter ice edge on the Lake Huron side of the Straits ran from Cordwood Point to Bois Blanc Island. It extended westward from Bois Blanc Island to Mackinac Island, then north and east past St. Martin and Les Cheneaux Islands to the vicinity of Martin Reef Light. South and east of the winter ice edge were concentrations of brash and small floes ranging from 5 to 7-tenths. Thun­ der Bay and Saginaw Bay contained solid winter ice covers. The southern basin below Harbor Beach contained large areas of drifting ice with con­ centrations ranging from 4 to 9-tenths. At that time the lake (including Georgian Bay) was estimated to be 45 percent ice covered.

The southern lake basin contained winter ice in the form of consoli­ dated brash and small to medium size ice floes of 10-tenths concentration. The ice-covered area was located south of a line running from Port Sanilac to Goderich. In Saginaw Bay and near Port Huron, portions of the ice cov­ er appeared rotten, and some areas contained a puddled snow cover. On March 9 a lake freighter followed a Coast Guard ship upbound through the ice cover on southern Lake Huron with little difficulty. On the downbound trip the freighter required assistance when it became fast in the ice near Port Sanilac (about 30 miles--48 km--north of Port Huron).

8 The freezing degree-day accumulations for Alpena reached their peak during the week ending March 30 (Plate 3). Because of the warm spell dur­ ing mid-March, it is supposed that the maximum ice cover was attained some­ time during the first or second week of March and covered approximately 50 percent of the lake surface. The warm spell had a pronounced effect on the ice cover, and by March 27 the lake was estimated to be 25 percent covered. The North Channel was still tightly closed by winter ice, as was the immediate Straits area, and the Cordwood Point - Bois Blanc - St. Mar­ tin Island area. Saginaw Bay contained ice concentrations averaging about 8-tenths, with ice extending out to Charity Island. The southern basin was covered from Point Clark to Kettle Point with 9-tenths concentration of large floes composed of half-rotten ice.

By the beginning of April, temperatures at Alpena were above freezing. This is indicated by a downward slope of the degree-day curve (Plate 3), which signaled the end of the ice season on Lake Huron.

Lake St. Clair

Three flights were made over the lake on February 4, 25, and March 4, 1969, and three ice charts were published from the data gathered (Plates 26, 27, and 28).

Shore ice was reported in the St. Clair Shores area on December 9. On December 22 a vessel required Coast Guard assistance when stopped by ice near Grosse Pointe. The low temperatures of late December and early January were ideal for ice formation on the lake. During the last two weeks of January, temperatures rose above freezing causing some breakup of the ice cover. The lake was first observed on February 4, and the to­ tal ice cover was estimated at 85 percent. Winter ice covered 80 percent of the lake. Open water was seen in the Belvidere Bay area near the Clin­ ton River, in the Huron Point area off Metropolitan Beach, and at the mouth of the Clinton River cutoff canal. The winter ice edge began just south of the Grosse Pointe Yacht Club, curving to the east and south, end­ ing on the Canadian shore near Belle River. Southwest of the ice edge was a band of open water 2 to 3 miles (3 to 5 km) wide. West of the ice edge were extensive areas of 7-tenths concentration of brash and small floes, drifting into the Detroit River.

On the February 25 flight ice was estimated to cover 65 percent of the lake. The cover contained large areas of puddled and refrozen winter ice. An area of open water covered most of Anchor Bay and extended south of Huron Point. The winter ice edge in the southwest portion of the lake had receded somewhat, and now formed a semicircle extending from near Gaukler Point (north of the Grosse Pointe Yacht Club) to the vicinity of Belle River on the Canadian shore.

At the time of the last flight (March 4), the northwest portion of the lake was almost entirely open except for fast ice in shallow areas. Ice was generally concentrated in the southern half of the lake and covered

9 approximately 50 percent of the lake surface. On March 22 the lake was observed to be ice free.

Lake Erie

Three reconnaissance flights were made over Lake Erie, resulting in publication of three ice charts (Plates 29, 30, and 31). The flights took place on February 4, 25, and March 22, 1969.

Ice was first reported on December 9 and 10 at the Fermi water level gage on the west shore and in the Marblehead and Barcelona areas on the south shore. The last part of December and the first two weeks of January were colder than normal, resulting in good ice forming conditions. This period is indicated by the steep upward slope of the Cleveland freezing degree-day graph (Plate 4). Lake Erie reacts rapidly to changes in air temperature and a considerable amount of ice cover was formed during this time. Temperatures moderated during the third week in January, and on January 17 the average daily temperature at Cleveland reached 40°F (4°C). Above freezing temperatures continued until January 24. Alternate thawing and freezing conditions predominated through the first week of February. The unseasonably warm weather played a significant role in the breakup and disappearance of much of the ice cover. On February 4 the lake was estimated to be 80 percent ice covered primarily with brash, and small to medium size floes. The western basin contained a 7 to 10-tenths concen­ tration of winter and young ice brash with open water at the Detroit River mouth, and in the area between Maumee Bay and Locust Point. A large open water area was observed along the south shore between Marblehead and Lorain

A 10-tenths concentration of winter ice was located, in general, east of a line running north from Cleveland to Port Maitland. Heavy rafted and jammed areas were present in the winter ice along the south shore and in the eastern end of the lake. There were three large open water areas along the north shore; the east side of Pelee Point, the east side of Pt. aux Pins, and just off the inner portion of Long Point Bay. Temperatures were moderate during most of February, which affected the ice cover to a considerable degree. On February 25 the lake was estimated to be 75 per­ cent ice covered. The entire area from Toledo to the Detroit River was clear except for shore ice in the Monroe area. The eastern limit of open water was along a line from Kingsville to Cedar Point on Maumee Bay. North west of the island area was a 7 to 8-tenths concentration of brash and small floes composed of half rotten ice. To the southwest was an area having 10-tenths concentration of consolidated brash and floes and contain­ ing areas of rotten ice. A large area of open water extended to the east of Pelee and Kellys Islands, and south to the entrance of Sandusky Bay.

The central basin was dominated by large areas of 9-tenths concentra­ tion of brash and small to medium size floes. Areas of open water paral­ leled the north shore from Pelee Point to Long Point. On the south shore the area between Huron and Mentor Harbor contained a 10-tenths concentra­ tion of consolidated brash and half rotten ice floes. Another area of 10- tenths concentrations of brash, cake, and floes extended into the lake as

10 far as Long Point, from the area between Ashtabula, Ohio and North East, Pennsylvania. The area contained a light snow cover and large offshore areas of heavy jamming, rafting, and ridging. Winter ice in the eastern lake basin was generally confined to the area east of a line running south from Port Colbourne to Silver Creek. That ice was of 10-tenths concentra­ tion and contained heavy, extensive ridging.

The maximum freezing degree-day accumulation for Cleveland occurred during the week ending March 16 (Plate 4). The warm weather of mid-March and the rotten condition of the ice cover caused the breakup and disap­ pearance of much of the ice. On March 22 the lake was estimated to be only 15 percent ice covered. Almost all of the ice at that time was concentra­ ted along the south shore and in the eastern basin. The area of 10-tenths concentration was located east of a line running from Port Maitland to the vicinity of Barcelona. That ice cover was composed of consolidated brash, cake, and small floes. The ice contained puddled or melted snow cover, and heavily jammed and rafted areas. West of this consolidated winter ice and along a line running from Long Point to Fairport Harbor, were concentra­ tions of brash ranging from 2 to 9-tenths. The ice breakup on Lake Erie followed the characteristic pattern, drift ice concentrating along the south shore and in the eastern end of the lake.

The last report of ice on Lake Erie was from the Black Rock Canal area, Buffalo Harbor, on May 2, 1969.

Lake Ontario

No ice reconnaissance flights were made over Lake Ontario by Lake Survey Center personnel. Ice information was obtained from ice charts produced by the Canadian Department of Transport, U. S. Coast Guard ice messages, and the Lake Survey Center water level gage observers. Shore ice and some drift ice was reported in the Cape Vincent area on December 10 and in the Rochester area on December 16. Olcott, New York, on the southwestern end of the lake, did not report ice until January 12. The graph of freezing degree-day accumulations for Rochester, New York (Plate 6), was used to estimate the date of maximum ice cover. The maximum de­ gree-day accumulation for the season occurred during the week ending March 16. The greatest areal extent of ice was assumed to have occurred just prior to that date. At that time the lake surface was estimated to be 10 percent ice covered. The cover was confined primarily to the eastern end of the lake and the approaches to the St. Lawrence River. The last report of ice was on April 9, 1969.

11 ACKNOWLEDGEMENTS

The information presented in this report was obtained through a sys­ tematic program of visual aerial observations performed during the winter of 1968-69, by the Ice and Snow project of the Lake Hydrology Branch of the Limnology Division, Lake Survey Center. The program was conducted un­ der the general supervision of Dr. L. Bajorunas, Director of the Limnology Division. R. N. Kelley and D. A. Prins served as principal ice observers. Flight support was provided by the Ninth United States Coast Guard District (U. S. C. G. Air Station, Traverse City, Michigan). A general coordination of flight schedules was maintained with the Canadian Department of Transport.

The data for this report were gathered before Lake Survey District, U. S. Army Corps of Engineers was transfered to the Department of Commerce, National Oceanic and Atmospheric Administration, National Ocean Survey with the title of Lake Survey Center. The transfer occurred on October 3, 1970.

12 TABLE 1 ICE CHART SYMBOLS

TOTAL CONCENTRATION BOUNDARIES

Open Water Observed

1-3 Tenths Coverage Assummed (Very Open Pack) Undercast 4-6 Tenths Coverage (Limits) (Open Pack) Limit of XVV\| 7-9 Tenths Coverage observed ANNA (Close Pack) area

10 Tenths Coverage (Consol Pack)

AGE AND SIZE OF FLOES

Station Model

A Cn C DOM, SEC n1n2n^ NEW

A - IND for Cn AGE OPENINGS IN ICE DOM - lOths DOM AGE SEC - lOths SEC AGE CRACK AGE - Y (Yng) - Young Ice (CRK) W - Winter Ice MW - Medium Winter LEAD TW - Thick Winter POOL or Cn - Total CONC of n.n, and POLYNYA n~ in lOths (PLY A) n - CONC of brash and cakes in lOths Relative n2 - CONC of small and movement medium floes in lOths between n- - CONC of large floes and two floes Ice fields in lOths

C - CONC of NEW ice in lOths NEW - SLH - Slush IR - Ice Rind SLG - Sludge PCK - Pancake TABLE 1 (CONTINUED)

TOPOGRAPHY

STAGE OF MELTING T COND Station Model T - Type of pressure Pd n, COND AAA - Rafted Pd - IND for Melting m - Ridged n - lOths of area 000 COND - TH - Thaw Hole - Hummocked R - Rotten Ice Rfzn - Refrozen COND - L - Light H - Heavy NOTE: No COND means MOD.

SNOW COVER ABBREVIATIONS Station Model AMT - Amount Sn BSH - Brash AMT, COND CKE - Cake CONC - Concentration Sn -• IND for Snow COND - Condition AMT -■ 0 - No Snow CONSOL - Consolidated L - Light DOM - Dominant H - Heavy IND - Indicator NOTE: No AMT means MOD MOD - Moderate COND - D - Drifted SEC - Secondary Cr - Crusted SLG - Sludge Pd - Puddle RFZN - Refrozen 2600 savq

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1

DEC JAN FEB MAR APR saw-33893(1 9NIZH8J aiivinunoDv

PLATE 2 APR

MAR

FEB

JAN

DEC

NOV

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PLATE 3 O l e tO u ttV A T W NFlW HT SAW-iia^a

9Ni2iiaj

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4 MAR

FEB

JAN

DEC

SAva-ii«9ia 9Ni7iiaj aiiynnwnoov

PLATE 5 LAKE SURVEY CENTER ICE. SUMMARY CHART 4-13 FEBRUARY 1969 ICC CONCENTRATION

Cuvuamo PLATE

6 SURVEY CENTER PLATE

7 SURVEY CENTER

Chicago PLATE

8 PORT ARTHUR

LAKE SURVEY CENTER ICE CHART LAKE SUPERIOR CTv r CO M •H & o — C cfl CO co 03 C a 0) O 0) CL) o O C I I I PLATE

vD CJT co ,fl o\ i t Q P — — U Cd Q)

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I I

9 PORT ARTHUR <\& CsL LU > >- O CC LLl 3 tn ZD LU l (T < o CJ LU X - cr _i < tn CL LU or o LU ZD PLATE VO CT\ CM CO •H H P*S o 0) I a3 a CJ I 03 0) cd a) a o c a aj o vD a\ r 1 S H Q — Uo U — cd 03 CD CVJ 1 1

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| 1 1 10 PORT ARTHUR CO cc >- QC =3 a LU LU LU I O LU o x < cr - LU CO CL Z> LU cr o ir PLATE ( P •H — cn cn a 0 Cl) CJ o G a 03 CO CO d c o <0 o B 1

1 11 SAULT STE. MARIE

A A 10 Sn W Y 820 H W H

LAKE SURVEY CENTER ICE CHART WHITEFISH BAY Ice Reconnaissance No. WB-1-69

Date 13 Feb 1969 STATl'TK MU KS Time 1014-1029

PLATE 12 LAKE SURVEY CENTER ICE CHART WHITEFISH BAY Ice Reconnaissance No. WB-2-69 Date 4 Mar 1969 ______„sr\ri 'Wni.'i ___ , Time 1030-1050 10 0 10

PLATE 13 W HD H

LAKE SURVEY CENTER ICE CHART WHITEFISH BAY Ice Reconnaissance No. WB-3-69 Date 11 Mar 1969 __ statu kmim-.___ Time 1038-1050 " " ’ ' ' ' °

PLATE 14 A _Sn W HCr

W HCr

SAIL! Sit. MARIE

LAKE SURVEY CENTER ICE CHART WHITEFISH BAY Ice Reconnaissance No. WB-4-69

Date 27 Mar 1969 ST.YI III- Mill Time 0949-1000

PLATE 15 LAKE SURVEY CENTER

ICE CHART r ^ WHITEFISH BAY Ice Reconnaissance No. WB-5-69 Date 3 Apr 1969 statute miles Time 1303-1326 ^ , _-r-T-r ■ y ™

PLATE 16 LAKE SURVEY CENTER ICE CHART 5T MARYS RIVER Ice Reconnaissance No. SMR-1-69

Date 13 Feb 1969 STATITK Mll.FS

Time 0958-1014 10 0 10

PLATE 17 LAKE SURVEY CENTER ICE CHART 5T MARYS RIVER Ice Reconnaissance No. SMR-2-69

Date 4 Mar 1969 STATUTE MILES Time 1050-1105

PLATE 18 PLATE 19 10 Sn tn C£ P- 5 ZD > LU >- Z cn c_> LU LU CC h- o UJ o X < Z O o < C/3 i h- C/3 O Li_ < tr < —

vO o> r k PLATE CQ z •H M O — l a a) c/3 Ctf a C/3 a Ctf c o

a\ vD rQ i CO i Pn — Q — jj a) a) cd I 1

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20 PLATE 21 W MDCr cn DC > DC 3Z LU LU >- O LU LU ZD cr < UJ a x c_> o z < * o < H CD o CO cr i < —

O' NO n S co S3 •H PLATE W pa o G a) CO CO 03 G u a) I o O C CO I o oj

ON

o rH -O' -4f CM h O H -H g a) I

22 PLATE 23 PLATE 24 m 10 Pd && W 532 5R ;V;V.::V.V^

BAY CITY

A _10 Pd W 820 5R PORT HURON

LAKE SURVEY CENTER ICE CHART LAKE HURON Ice Reconnaissance No. H-l-69

Date 4 Mar 1969 STATUTE MILKS

Time 1108-1336 0 10 20 30 40 50 60

PLATE 25 PLATE 26 PLATE 27 PLATE 28 PLATE 29 PLATE 30 PLATE 31