U.S. DEPARTMENT OF COMMERCEFrederick B. Dent, Secretory

NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION

Robert M. While, Administrator

ENVIRONMENTAL RESEARCH LABORATORIESWilmot N. Hess, Director

NOAA TECHNICAL REPORT ERL 325-GLERL 1(GLERL Contribution No. 20)

Great Lakes Ice Cover, Wil1ter 1913-14

R.A.ASSEL

BOULDER. COLO..July 1974

For sale by the Superintendent of Documents, U. S. Government Printing Office, Washington. O. C. 20402

ENVIRONMENTAL RESEARCH LABORATORIES

TIle: mission of the Environm-entat Ruse:arch LibofatQrics is to itudy the oua.ns. inl<lnd waters. the lowerand upper atmosphere, the space covironmenl, ilnd the ciTth, in search of the underStanding needed to pro­vide more useful services in improving man's prospe<:u for survival as inf1uenc~ by th~ physical environment.labofatories conuibuling to these studies are:

Atlantic Oceanographic and M~te()rologk()1Lobororor;('s (AOML): Geology .and geophysics of occan basinsand borders, oceanic process,e$, sea·air interactions and remou: sensing of ocun prousses and characteristics(Mi.mi, florid.).

Pucifk Mari~ Environmental Loborotory (PM£L): Environmental pto,esw:s with emphasis on monitoringilnd predicting the effects of man's activities on estuarine, COJsut• .lnd ne~(-shore mJrine processes (Seatde,W>SIlingtonI.

Grt'ilt Lakes Environmental R~seor,h Laborotory rGL ERL): Physiul, chemical, ~nd biological. limnology,take~air interactions,lake hydrology,lake level forec~tinl, .and l~ke ice studies (Ann Arbor, Michigan).

Atmosph¥rJc Physics lInd Chemistry Laboratory (APCL): Prousses of cloud and precipUtion physia;chemical composition and nude~tin& subsunus in the lower almosphere; and bbor.atory and field experimentstoward developing fe.uible methods of \n.ther modifiGation.

Air Resources Laboratories (ARL); Diffusion, tT.ansport, and dissipation of atmospheric conuminants;de.elopment of methods for prediction and GOfttfoi of atmospfte-ric pollution; leophysical monitoring for<lIm.!i< m.nge ISilver Spring, M.ryl.ndl.

Gtophys/Ctl/ Fluid Dynamics Laboratory (GFOL): Dynamics and physics of eeophysicaf fluid systems;development of .I theored"' basis, through mathematical moddine and computer simulation, for the behilvlorand properties of the atmosphere and the oceans (Princeton, New Jersey).

Ntll;OfMI S.wt'~ Storms LabofQtory (NSSL): TorQdoes, squiUl Una, thunderstorms, ~d other severe localconvective p1w:nomen.a directed toward improwd methods of prediction Ind detection (Norman~Oklahoma).

Sp«~ El1vironm~nt LobortJtOf)l (SEL): Sollr~tertc!strill physics, service and technique development in theareas of environmental menitonn. and forecutlng. . •

An-anomy LfIborqtory (AL).- Theoretical. laboratory, rCKket, ;and s;tcUitt studies of the physica' and:chemical proc~ controlUng the Ionosphere .nd eXO$phere of the earth and other plaMts, and of thedynamics of their interactions with hi,h.-altitude meteorology.

Wave' Propagation Laboratory (WI'L): Development of new methods for remote sensing of the geophysicalerwironment with 'Pec~1 emphasis on optiul, microwave and acoustic sensing systems.

Mt1rin~ EcoSystem AntJlyJls I'rogrtJm Office (MESA): PSans and directs interdisciplinary analyses of thephysical. chemic.I, geological. and bioloaical characteristics of selected coastal regions to assess the potentialeffects of O(Qn dumping~munici~landindustrial waste discharges, oil pollution, or other activity which m.Jyhave environmental imput.

Weather Modiflcotion Program OffJu (WMPO): Plans .and directs ERL 'Neither modification researchictivlties in pn~cipitation enhancement and severe storms mitigat.on and operates ERl's reseuch aircraft.

NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATIONBOULDER, COLORADO 80302

DISCLAIMER

The NOAA Environmental Research Laboratories do not approve,recommend. or endorse any proprietary product or proprietarymaterial mentioned in this publication. No reference s1ulllbe made to the NOAA Environmental Research Labot:atories, orto this publication furnished by the NOAA EnvironmentalResearch Laboratories, in any advertising or sales promotionwhich would indicate or illlply that the NOAA EmrironmentalResearch Laboratories approve, recommend. or endorse anyproprietary product or proprietary material mentioned herein,or which has as its purpose an intent to cause directly orindirectly the advertised product to be use~ or purchasedbecause of this NOAA Environmental Research Laboratoriespublication.

ii

CONTENTS

ABSTRACT1. INTRODUCTION2. DATA COLLECTION3. DATA PRESENTATION

3.1 Freezing Degree-Days3.2 Composite Ice Charts3.3 Ice Charts

4. DISCUSSION4.1 Winter Characteristics4.2 General Seasonal Trends in Ice-Cover Distribution4.3 Lake Superior4.4 St. Marys River4.5 Lake Michigan4.6 Lake Huron4.7 St. Clair River and Lake St. Clair4.8 Lake Erie4.9 Lake Ontario

5. ACK.NOWLEDGMENTS6. APPENDIX

iii

Page

12222444466789

1011121314

A.I.

A.2.

A.3.

A.4.

A.5.

A.6.A.7.A.8.A.9.A.IO.A.H.A.12.A.l3.A.14.A.15.A.16.A.H.A.18.A.19.A;20.A.21.A.22.A.23.A.24.A.25.A.26.A.27.A.28.A.29.A.30.A.3I.A.32.A.33.A.34.A.35.A.36.A.37.A.38.A.39.

FIGURES

Accumulated freezing degree-days - Lake Superior atSault Ste. Marie, Mi~h., and Duluth, Minn.Accumulated freezing degree-days - Lake Michigan atGreen Bay and Milwaukee, Wis.Accumulated freezing degree-days - Lake Huron atAlpena, Mich.Accumulated freezing degree-days - Lakes Erie andSt. Clair at Cleveland, Ohio, and Detroit, Mich.Accumulated freezing degree-days - Lake Ontario atRochester, N. Y.Composite ice chart - week ending December 16, 1973.Composite ice chart - week ending December 23, 1973.Composite ice chart - week ending December 30, 1973.Composite ice chart - week ending January 6, 1974.Composite ice chart - weekending January 13, 1974.Composite ice chart - week ending January 20, 1974.Composite ice chart - week ending January 27, 1974.Composite ice chart - week ending February 3, 1974.Composite ice chart - week ending February 10, 1974.Composite ice chart - week ending February 17, 1974.Composite ice chart - week ending February 24, 1974.Composite ice chart - week ending March 3, 1974.Composite ice chart - week ending March 10, .],974.Composite ice chart - week ending March 17, 1974.Composite ice chart - week ending March 24, 1974.Composite ice chart - week ending March 31, 1974.Composite ice chart - week ending April 7, 1974.Composite ice chart - week ending April 14, 1974.Composite ice chart - week ending April 21, 1974.Composite ice chart - week ending April 28, 1974.Lake Superior ice chart - March 4, 1974.Whitefish Bay ice chart - March 4, 1974.St. Marys River ice chart - December 17, 1973.St. Marys River ice chart - March 4, 1974.Lake Michigan ice chart - February 27, 1974.Lake Michigan ice chart - March 4, 1974.Lake Huron ice chart - February 25, 1974.Lake Huron ice chart - February 27, 1974.Lake Huron ice chart - March 4, 1974.Lake St. Clair ice chart - February 5, 1974.Lake St. Clair ice chart - February 25, 1974.Lake Erie ice chart - February 25, 1974.Lake Ontario ice chart - February 15, 1974.NOAA-2 VHRR visible image - February 20, 1974.

iv

Page

14

15

16

17

1819202122232425262728293031323334353637383940414243444546474849505152

TABLES

1. Ice reconnaissance flights - winter 1973-742. Key to ice chart symbols

v

Page

35

GREAT LAKES ICE COVER, WINTER 1973-74

R. A. Assel

ABSTRACTTwenty composite ice charts were produced from ice­

cover data received at the Lake Survey Centerl during thepast winter. These charts illustrate estimated ice con­centrations and distributions on the Great Lakes at weeklyintervals from mid-December 1973 to the end of April 1974.In addition, 13 ice charts compiled from data collected byLake Survey Center ice observers portray synoptic ice con­ditions on individual lakes and rivers.

Freezing degree-day accumulations-indicate the 1973­74 winter was near normal over the Great Lakes. Accumu­lations were near their seasonal maximum the end of Feb­ruary on southern portions of the Great Lakes and the endof March on northern portions.

Extensive ice formation in protected shore areas andshallow parts of the Great Lakes was initiated by belownormal temperatures the second half of December and firsthalf of January. Above normal temperatures the secondhalf of January retarded ice formation and caused signif­icant loss of ice in some areas. Ice covers reached theirmaximum extent in February and were estimated to extendover 70 percent of Lake Superior, 20 percent of Lake Mich­igan, 65 percent of Lake Ruron, 95 percent of Lake Erie,and 25 percent of Lake Ontario. Mild temperatures in earlyMarch resulted in rapid loss of ice on southern portionsof the Great Lakes so that, by mid-March, they were virtu­ally ice free. By mid-April, the bulk of the ice cover wasgone-on the northern portions of the Great Lakes as well.The only areas with extensive ice in mid-April were thewest end of Lake Superior, various Lake Superior bays, andthe North Channel in Lake Huron. Last reports of ice weremade in late April.

lIn April 1974, the Limnology Division, Lake Survey Center, NationalOcean Survey, was transferred to the Great Lakes EnvironmentalResearch Laboratory of the Environmental Research Laboratories.Several references to the Lake Survey Center appear since the workwas being conducted under that organization at the time.

1. INTRODUCTION

The Great Lakes Environmental Research Laboratory has an ongoingproject for the investigation of lake ice-cover distribution. Reportsdescribing work carried out under this project for past winters, begin­ning with the 1962-63 winter season, are available from the Lake SurveyCenter, Detroit, Mich. In this report, data collected during the 1973­74 winter are described. As in previous reports in'this series, thisreport contains a description of ice-cover fo~tion, growth, und dec~y

based on data collected the past winter. A brief sUllldlary of wintert~mperatures is also incluced.

2. DATA COLLECTION

Ice charts, satellite imagery, and surface ice reports made up thebulk of the ice-cover information collected. Ice charts were receivedfrom the Ice Navigation Center, Cleveland, Ohio, and Ice ForecastingCentral, Ottawa, Canada, throughout the winter. Lake Survey Centerpersonnel also produced ice charts from data collected on visual aerialice reconnaissance flights. The primary information on ice charts isice concentration. ice distribution, and age and size of ice floes.Surface reports of ice thickness and ice conditions were received fromLake Survey Center and U.S. Coast Guard ice observers. NOAA-2 VHRRsatellite imagery was received from the National Environmental SatelliteService in Washington. D.C •• from November 1973 through April 1974.

Lake Survey Center personnel completed 12 aerial ice reconnaissanceflights between December 17. 1973, and March 21. 1974. Approximately37 hours and 3660 miles (5860 km) were logged on tpese flights. themajority of which used chartered Cessna 172 and Cessna 182 aircraft.Three flights were made aboard U.S. Coast Guard aircraft during icepatrol flights. Flight dates and areas covered are given in table 1.

Data collected on aerial ice reconnaissance flights included obser­vations of ice concentrations, ice distributions, ice floe size, iceage, and surface characteristics. This information was plotted on work­sheets and redrafted on small-scale ice charts, which were sent to theIce Navigation Center in Cleveland after each flight. Aerial photo­graphy of ice cover was also made on most flights over the St. Marys andSt. Clair Rivers in support of the Demonstration Program to extend thenaVigation season. Four visual aerial ice reconnaissance flights weremade to coincide with the time of estimated maximum ice cover on theGreat Lakes as part of the ongoing lake ice-cover distribution project.

3. DATA PRESENTATION

3.1 Freezing Degree-Days

As in past winters, freezing degree-day accumulations, based onaverage weekly temperatures, were maintained for selected NationalWeather ,Service meteorological stations on the perimeter of the Great

2

Table 1. Ice Reconnaissance PZights - r-linter 1973-74

Flight No. Date Area

1 Dec. 17 St. Marys River

2 Jan. 8 St. Marys River

3 Jan. 17 St. Clair River, !..ake St. Clair

4 Jan. 24 St. Marys Riv~r

5 Feb. 5 St. Clair River, Lake St. Clair

6 Feb. 15 Lake Ontario

7 Feb. 25 (CG) Lake Erie

8 Feb. 25 St. Clai~ River, Lake St. Clair,Southern Lake Huron

9 Feb. 26 St. Marys River

10 Feb. 27 (CG) Northern Lakes Michigan andHuron

11 Mar. 4 (CG) Northern Lakes Michigan and!luron, Lake Superior, andSt. Marys River

12 Mar. 21 St. Marys River

(CG) = Coast Guard Flight Support

3

Lakes: Duluth, Minn.; Sault Ste. Marie, Mich.; Alpena, Mich.; GreenBay, Wis.; Milwaukee, Wis.; Detroit, Mich.; Cleveland, Ohio; and Roch­ester, N. Y. Freezing degree-days measure the cumulative temperaturedeparture from 32°F (O°C). One freezing degree-day is accumulatedwhen ~he mean daily temperature is 31°F. The mean daily temperatureis defined as the mean of the daily maximum and minimum temperatures.Thus, for a mean daily temperature of 2SoF, 7 freezing degree-days areaccumulated. Graphs of freezing degree-days are given for each of theGreat Lakes (fig. A.l through A.S). The graphs show 1973-74 accumu­lations and a IO-year mean.

3.2 Composite Ice Charts

Twenty composite ice charts (fig. A.6 through A.25) illustrate theseasonal pattern of ice formation, growth, and decay on the Great Lakesfrom Decemher 16, 1973, to April 28, 1974. These charts portrayestimated ice conditions at weekly intervals, based on a subjectiveevaluation of available ice-caver information. Ice charts compiledby the Lake Survey Center, U.S. Coast Guard Ice Navigation Center. andCanadian Ice Forecasting Central provide the bulk of the ice-caver infor­mation used to compile composite charts. NOAA-2 VHRR satellite imagerywas used to supplement these data.

Freezing degree-day accumulations at the eight locations notedearlier also are given on the composite ice charts. Weekly, seasonal.and normal seasonal accUlllulations are given to indicate the severityof each week and the relative severity of the seasonal accumulations.

3.3 Ice Charts

Thirteen ice charts. figures A.26 through A.38. compiled by theLake Survey Center, illustrate synoptic ice conditions and providegreater detail than composite ice charts. Table 2 is a key to symbolsand abbreviations used on these charts. Data for eight of the icecharts were collected on flights near the time when it was estimatedthe lakes would have their greatest ice caver. The remaining five icecharts were made during flights over the St. Clair and St. Marys Riversin connection with the Lake Survey Center's participation in the GreatLakes-St. La~nce Seaway Navigation Season Extension DemonstrationProgram.

4. DISCUSSION

4.1 Winter Characteristics

Two values of freeZing degree-day accumulation can be used tocharacterize a winter season: (1) maximum accumulation and (2) dateof maximum accumulation. The first value gives a measure of winterseverity; and the second value, that is, the "date, marks an inflection

4

TOTAL COIICENTRATION

TabLe 2. Key to Ice Chart SymboLs

OPENINGS IN ICE BOUNDARY

[illi-:.::.: OPEN WATER

/'CRACK OR BROKEN OBSERVEDTRACK VISUALLY§ 1-3 TENTHS COVERAGE

(VERY OPEN PACK) :::- LEAD ---- ASSUMED

rrrn 4-6 TENTHS COVERAGE(OPEN PACK) (fJ) POOL OR POLYNYA ~UNDERCAST(PLYA) (LIMITS)

~7-9 TENTHS COVERAGE(CLOSE PACK)

~llELATIVE MOVEMEII ..._-- LIMIT OF

f§§ 10 TENTHS COVERAGE BETWEEN TWO FLO OBSERVED DATA(CONSOL PACK)

AGE AND SIZE OF FLOESStation Model

• CnACTUAL AGE (Ul) (n2) (n3)

A -IND !OR ACTUAL AGEACTUAL AGESS -1lllW ICE 2" or lessTHIN -THIN ICE 2-6"KED -KEDIUM ICE 6-12-TIlK -THICK ICE 12-30"V'1'lIX -VERY THICK 30" or)

Cn - Total C(JI(C of nlu2 and03 in lOths

nl - CONC of brash andcakes in 10ths

u2 - CONC of small andmedium floes in IOths

n3 - COlIC of big floes andice fields in 10ths

....!!....\0

SMa.! COVEll.Station lloJel

(n)s" IND for Snow

" (n) - Tenths on lee7ii1--------

STAGE OF MELTINGStation !Ioclel

Pd(n)+(n)'1B+(n)F

Pd - IND for Helting(n) - Tenths on Ice(n)TH - Tenths Thaw Holes(n)F - Tenths Frozen

TOPOGRAPHY ABBllEVIATIOIIS

~ - RAFTED BSH • Brash(n)

CakeCK -IVV\ - RIDGED

Not Observed(n) NOT OBS -

no HllMMOCKED SLG • Sludge(n)

RefrozenRFZN =(n) - NUMllER OF TENTHS

5

point separating a period of generally increasing ice formation poten­tial from a period of decreasing ice formation potential. Using Rondy's2classification of winter severity, which is based on maximum freezingdegree-day accumulations, the 1973-74 winter was in general normal.Dates of maximum freezing degree-day accumulation occurred in lateMarch and early April on the northern half of the Great Lakes and inlate February on southern portions, with accumulations at Clevelandoccurring in mid-January to prOVide an exception to this trend. Aver­age dates of maximum freezing degree-day accumulation given in theGreat Lakes Ice Atlas indicate that the 1973-74 maximum accumulationswere nearly normal on northern portions of the Great Lakes, that is,at Duluth, Sault Ste. Marie, Alpena, and Green Bay, while maximum accu­mulations were 2 to 4 weeks earlier than normal on the southern half ofthe Great Lakes, that is, at Milwaukee, Detroit, Cleveland" and Rochester.

4.2 General Seasonal Trends in Ice-Cover Distribution

Ice covers were in general confined to bays, harbors, and shallowprotected areas of the Great Lakes through late January (fig. A.6through A.12). In February (fig. A.13 through A.16), ice formed overdeeper waters of the lakes and attained its greatest coverage. Mildspring-like weather the first half of March resulted in.loss of icecover 80 that by mid-month the southern half of the Great Lakes wasvirtually ice free (fig. 'A.17 through A.19). A cold period' the last2 weeks of March accounted for some new ice formation. ~spe~ially onnorthern lakes (and Lake Superior in particular). as shown in figuresA.20 and A.21. lee covers were well into the decay period by mid-April(fig. A.22 and A.23), and by the end of Apri~. the only ice of anysignificant coverage was located in the west end of. Lake Superior~ inthe three large bays along the north shore of that lake. and in theNorth Channel of northeru Lake Buron (fig. A.24 and A.25).

4.3 Lake Superior

Lake Survey Center ice observers made one flight over Lake Superioron March 4 and produced two ice charts from that flight, figures A.26and A.27. The iee cycle of Lake Superior. based on available data, isdescribed below.

Bays and harbors began to freeze over during the second week inDecember. By January 20. the southwest end of the lake from Duluth toAshland and eastward to esst of Ontonagon had extensive shore ice.

2Rondy, D.R. (1971), Great Lakes Ice Atlas, NOAA Technical MemorandumNOS LSCR 1, Lake Survey Center, Detroit, lIich.

6

The three bays along the north shore were frozen, with the ice extendingfrom the mainland to Isle Royale. Whitefish Bay at the east end of thelake was frozen over. Above normal temperatures the second half ofJanuary slowed the rate of ice formation and caused the loss of some icecover. More seasonable temperatures through the first 3 weeks of Feb­ruary resulted in extensive ice formation over the lake. By the week end­ing February 17, freezing degree-day accumulations were within 75 percentof their seasonal maximum values, and the lake was estimated to be lO-per­cent ice cover and near its maximum ice cover for the l~l3-l4 season.

The following ice conditions were observed on an ice reconnsissanceflight over Lake Superior on March 4. Whitefish Bay was completely fro­zen over, and the south end of the bay had only a little snow on the ice(see fig. A.27). The lake beyond the bay (fig. A.26) was ice free withthe exception of scattered brash ice. Belts of brash, covering 10 to 20percent of the area, were observed along the east shore. An open water'area extending from Whitefish Point to Munising gradually became largergoing west. Shore ice was located south of the open water and brashice of various concentrations north of it, while the central part of theeastern half of the lake was virtually ice free. Going west, brash icewas once more observed approximately west of a line from Houghton to Mar­athon. A large pool of open water paralleled the south shore of IsleRoyale and extended eastward from iF, but ice covered 90 t9 100 percentof the observed area west of Isle Royale; however. observation of thewestern half of the lake was severely limited by snow flurries. Raftingand ridging were evident in portions of the weatern lake ice cover andcracks and leads. predominstely north-south oriented, were observedthroughout that area. New ice was forming on t~ open water area.

A NOAA-2 satellite image taken February 20 illustrates the generaldistribution pattern of ice cover on Lake Superior near the time ofestimated maximum ice cover (fig. A.39).

Mild spring-like weather the first part of March greatly reducedice cover on the lake, as shown in figures A.lS and A.19. By March 17.the eastern half of the lake had only shore ice remaining and theweatern half had large areas of open water. Low temperatures tbe lasthalf of March brought extensive new ice formation so that the lake wasonce more near maximum ice cover during the second half of March. Mildtemperatures in April brought an end to significant ice formation. Bymid-April, the lake was well into the decay period (fig. A.23). Baysand harbors were losing ice covers in the third and last week of April.By the end of the first week in May, all ice reports indicated thetthese areas were virtually ice free.

4.4 St. Marys River

Two ice charts were produced from visual aerial ice reconnaissance

7

flights made over the St. Marys River, one on December 17, 1973, andthe second on March 4, 1974. The following paragraphs describe thedevelopment of ice on the river.

Shore ice was reported forming on the southern end of the riveron December 3 and on the northern part of the river above the locks onDecember 11. On the December 17 flight (fig. A.28), the river fromjust north of De Tour to Neebish Island and further nort~ along theeast side of Sugar Island contained an almost complete ice cover.Numerous cracks, leads. and ~ brash-filled ship track were observedsouth of Neebish Island. There were also scattered areas of snow onthe ice. Along the west side of Sugar Island up to Sault Ste. Marie,the river contained shore ice and brash. Low concentration of brashwas also observed from the mouth of the river to the southern tip ofSt. Joseph Island.

By the third week in January. the river was completely ice covered,with the exception of a few open water areas in the vicinity of thelocks and in the river channel. The last ship passed through thelocks at Sault Ste. Marie on February 6. 1974. ending a navigationSeason that had started on March 28, 1973.

The river remained ice covered through early lK.arch with little signsof decay. On March 4. it was observed to be still completely icecovered (fig. A.29~ and a refrozen ship track could be seen itsentire length. The first ship passed upbound through the locks onApril 2, 1974. The ice cover on the northern part of the river startedbreaking up in early April, parttally due to ship'traffic and icebreak­ing activities. By mid-April. the ice cover on the southern half ofthe river was also showing signs of decay as icebreaking activity andmild weather took their toll. For all practical purposes. the riverwas ice free by May 1, 1974.

4.5 Lake Michigan

Visual aerial ice reconnaissance flights were made over the northernporl:ions of Lake M.ichigan on February 27 (fig. A.30) and March 4 (fig.A.31). The general areal pattern of ice cover given below is basedprimarily on ice charts.

Ice began forming in the Straits of Mackinac and in Green Bay bymid-December. as shown in figure A.6. Much below normal temperaturesthe first 2 weeks in January, indicated by the upward slope 9f thefreezing degree-days graphs on figure A.2, resulted in extensive icecover formation in Green Bay, the Straits of Mackinac west to BeaverIsland, and in the south end of the lake, as shown in figure A.lO.Above normal temperatures the last half of January resulted in loss ofice cover on the southern lake area and little net change in lakewarde..xtent of ice in the northern end of the lake as evidenced by figures

8

A.ll and A.lt. Ice began forming in mid-lake areas of the northern endof the lake in the first half of February, resulting in maximum iceextent with ice covering an estimated 20 percent of the lake's surface(see fig. A.13 thr6ugh A.15). By February 17, freezing degree-day accu­mulations for Green Bay and Milwaukee were over 85 percent of their max­imum value for 1973-74.

During maximum ice cover, ice extended from the north entrance ofGreen Bay to Grand Traverse Bay. Green Bay and the Straits of Mackinacto Beaver Island weTe completely ice covered, while most of the openlake north of a line from Escanaba to Charlevoix was 70-to 90-percentice covered. In the south end of the lake, shore ice of five- toseven-tenths concentration extended from Milwaukee southward.

On February 27, the following ice cond:l.tions weTe observed on afllght over the north end of the lake. Green Bay and the Straits ofMackinac had a snow-covered ice sheet. West of the solid ice in theStraits, brash ice of various concentrations lined the shore extendingto the vicinity of Manistique, Mich. The lake to the east of BeaverIsland contained brash of decreasing concentration southward.

Unseasonably mild weather in the first half of March. evi.denced tythe downward slope of the freezing degree-day graphs for Lake Michigan(fig. A.2). resulted in loss of ice in mid-lake areas at the north endof the lake. On March 17. the bulk of the ice was located in Green Bayand the Straits. Ice in these are.t\s was $radually lost over the nextmonth. By mid-April (fig. A. 23). Lake Michigan was essentially ice free

4.6 Lake Huron

Visual aerial ice reco~~issance flights were made over Lake Huronon February 25. 27, and March 4. Observed ice conditions on these datesare portrayed in figures A.32 through A.34.

Bays and harbors had begun to freeze over by the third week ofDecember. By the end of the first week of January. Saginaw Bay wasice covereil, and the Straits east to Cheboygan. Mich., were 70- to 90­percent ice covered. Although ice cover continued to increase throughthe second week in January, mild temperatures retarded ice growth duringthe second half of January. In February, ice formed over the open areasof Lake Huron. and the lake was· estimated to be near maximum ice coverbetween February 10 and 24. During that period, the lake was estimatedto be 65-percent ice covered. On February 24, freeZing degree-dayaccumulations at Alpena were 88 percent of the maximum season value.An intense ~inter storm mOVed over the Great Lakes on February 22 and23, causing significant changes in ice-cover ,concentration and distrib~­

tion. On February 27 (fig. A.34). the following ice conditions were ob­served: the Straits to Cheboygan had snow-covered ice, while a mixtureof thin and thick ice covering 70 percent of the lake's surface extended

9

east of Bois tlanc l<;lan1 over much of the lake north c.f a line fromAlpena to De Tour and along the ncr-til short" from De Tour eastward.Brash io: c,f lessf>r ('oncentrations was located lakeward of the icealong the north shore. FrOlll AlpenA sOOJthward, ice of six- to eight­tenths concentration was lo~ated along the shore beyond an open waterarea from Alpena to HarrisvIlle. The north end of Saginaw Bay was ten­tenths ice.covered and a lead was observed along the northeast shore.Beyond the solid jce in the bay,'brash, covering 10 percent of the area,continued eastward many miles into the lake.

Ice cover, in genera], decreased in lfarch due to mile temperatures.FreezIng .'egree-days at Alpena (fig. A.3) had a negative slope the weekending March 10, indicating a thaw period. By Apr!.l 7, the only area

. \lith significant lee coy"r was the northeast part of the lake. incllld­ing North Channel and Georgian Bay. By the fourth ~leet; of Apr~.l. theice in thes~ northern areas was deteriorating rapidly.

4.7 St. Clair River and Lake S!:. Clair

Ice charts w~re produced for the February 5 and 25 flights overthe St. Clair River and Lake St. Clair (fi~. A.35 and A.36).

Ice was first reported on the St. Clair ~iver on December 17.Above. freez:l:l8 tel'.lperatures during the last ~7eek of Decetnber, hoyever.made the rciver virtcally :lee free by the end of that month. Anotherperiod of ice formation started in early January and continued throughthe secorul week of that month. A thaw period starting the third weekof the month. reminiscent of the. January 1973 tb3w, resulted in ice­free condltions on the river hy late January.

Low temperature returned during the first 2 weeks of February.causing rapid ice formation on both southern Lake Huron and the St.Clair River. An ice bridge was obs~rved at Port Huron on February 5.On that date, the river was estimated to be seven- to nine-tenths icecovered and an ice jam was observed in the vicinity of Algonac. 011February 25. the river was 30 to 40 percent covered with newly formed icebetween Algonac and Stag Island. The upper river, north of Stag Island,had only shore ice. while southern Lake Huron was estimated to be 90­percent ice covered.

Unusually mild weather in early March brought an end to significantice cover on the St. Clair River. The river was virtually ice free onMarch 3. although a cold spell March 24 to 26 brought widespread newice formation of short duration. The last report of ice on the riverwas dated March 30.

Ice was first reported on Lake St. Clair on December 16. By January6, the lake had a complete ice cover. As can be seen from figure A.4,above normal temperatures the last half of January, indicated by the

10

freezing degree-day graphs for Detroit and Cleveland, caused deteriora­tion of the ice cover. By the last week of the month (fig. A.12), LakeSt. Clair had less ice than normal.

Ice covered the entire lake in early.February; and on a flight onFebruary 5 (fig. A.35) the lake had a medium-thick ice sheet with snowcovering 20 to 30 percent of the ice in mid-lake.

The lake retained its complete ice cover until the last week ofFebruary (fig. A.36). when mild weather caused deterioration of the icecover. Mild temperatures dominated the first half of March. The lakewas for the most part ice free by March 10, as shown on figure A.18,although some new ice formed during the last half of March (fig. A. 20).Last reports of ice clUlle from the north end of the lake on March 25.

4.8 Lake Erie

Lake Survey Center personnel made one flight over Lake Erie in lateFebruary (fig. A.37).

The bays and harbors in western Lake Erie began to freeze over inmid-Decembe~as shown on figure A.6, with the last ship passing throughthe Welland Canal on December 31. The perimeter and western end of thelake were the main areas of ice forma.tion-in .January. A thaw the secondhalf of that month caused reduction of ice cover so that by .January 27(fig. A.12) the main body of ice was located along the north shore ofthe western end of the lake. Ice began forming over the entire lakethe first week in February, and by February 10 (fig. A.14) the lake wasnear lllaXimum ice cover. Ice cover neared the lllaXimum extent inter­trlttently during the last 3 weeks of February in resp,onse to changingweather conditions. Freezing degree-day accumulation at Cleveland wasapproximately 80 percent of its maximum value on February 17 (fig. A.4).On February 25. the lake was estimated to be 95-percent ice covered. Azone of thin and new ice was observed along the northern shore on thatdate. Medium-thick ice with a 30- to 40-percent snow cover was observedlakeward of the thin ice. The rest of the lake's perimeter was observedto have medium-thick ice of nine- to ten-tenths concentration with vari­able snow cover.

The ice cover decreased in extent in early March, and by mid-month(fig. A 19). there was very little ice left. An area of ice persistedin the eastern end of the lake through the end of March. The WellandCanal opened on March 29, 1974, and the last report of ice came fromBuffalo, N. Y., on April 4.

11

4.9 Lake Ontario

Figure A.38 portrays observed ice conditions on eastern Lake Ontariofor February 15 and is based on a Lake Survey Center ice reconnaissanceflight made over that area.

Low temperatures the second and third weeks of December brought iceformation to the bays in Lake Ontario with the St. Lawrence Seawayclosing on December 20, 1973. The last week in December was mild withtemperatures for the week averaging above freezing at Rochester,N. Y., as evidenced by the downward slope of the f~eezing degree-daygraph in figure A.5. December's temperature pattern was repeated inJanuary as the first half of that month had low temperatures followedby milder weather the last half. As a result, the ice cover. which wasmost prominent in the northeast area of the lake, advanced and retreatedin January as shown in figures A.lO and A.ll. Low temperatures the sec­ond and third weeks of February coincided with the period of maximum icecover on Lake Ontario. On February 17, freezing degree-day accumulationat Rochester was at 98 percent of its seasonal maximum. Two days earli­er, February 15. the lake was estimated to be 25-percent ice covered.

The ice conditions illustrated in figure A.39 were observed on aflight over the lake on February 15. Thin ice of four- to five-tenthsconcentration was observed from Rochester to Oswego, N. Y., ranging3 to 8 mileS (5 to 13 km) into the lake from shore. A semi-circu-lar shaped zone of complete ice cover paralleled thp shore fromthe southeast and of the lake to the northeast shore. Lakeward, amixture of thin and medium ice of nine-tenths conoentration and a zoneof brash ice beyond that extended many miles into the lake. Thick SllOW­

covered ice extended from bays and harbors to the islands in the north­east end of the lake, while a light dusting of snow covered much of theice surface along the southeast shore.

Much of· the ice in the open lake was gone by early l.farch as mildweather, evidenced by the sharp drop in freeZing degree-day accumula­tion in figure A.5, caused deterioration of the existing ice cover.By early ~mrch (fig. A.17). the bulk of the open lake ice was gone.Lower temperatures the last half of the month helped preserve existingice cover. The last report of ice came from Cape Vincent, N. Y., andwas dated March 29.

The St. Lawrence Seaway opened on March 26. recording the earliestopening date in its IS-year history.

12

5. ACKNOWLEDGMENTS

Lake Survey Center visual aerial ice reconnaissance activities werecarried out under the general guidance of Dr. L. Bajorunas, Chief ofLimnology Division, and Dr. F. H. Quinn, Chief of the Lake HydrologyGroup. and were under the supervision of C. Adams of the Lake HydrologyGroup. Ice observers included C. Adams, G. Leshkevich. and M. Eisenstat.

Flight support was provided by the U.S. Coast Guard. Ninth District(U.S.C.G. Air Stations, Detroit, Mich., and Traverse City, Mich.) •.

Climatological data used in this report were taken from the U.S.Department of Commerce publication Weekly Weather and Crop Bulletin.

13

~

~

C7'.

,

,._0_.-......·""1973-71i'·....

D1l1.UTlt 1111lN. / 1 '., ...-~ -MEAN .............

.........r "./ ~

/.//- _.-.........

v'/ r~MEAN "~973-~4

/ V .'/ ~r1l1.T STE. KJIE. MICH./~,.,- /

1/ / /'l'i / ~I A

I /~/-;7I 1//'/,/ oJ

.1/, V:/ .I,

/ft/', ./ '//'_'_'_::;;::'~..,..,,

2400

'600

...

:lOCO

<CO

.000

.. 2200>.IIC '000•••~ ,_III

•o ,.00IIIc0" 1400

••~ 1200

"'l:I• 1000-II:> 100E:>...... ...«

!i;:

J M) 15 23 25 ~l s 10 tJ 20 21 ~. • 10 \S 20 2S »" , 10 tI 20 2S' S I) 15 20 a 30' -$ ~ ~ ~ 2S 30:

NOV DEC JAN FEB MAR APR

F{.gw.te A.t. AaaumuZatBd fr'essing dBfl1'es-days - Lake Superior at 8au~t 8t8.Ma.ztU, Mich., and Dututh, Minn.

VII

'V ". :; / / /.l

1//

~ /( "~ "....

( I ~..,.T to,T .....,

'" il!i: I ~I

...Il. \ . i lil

~ \..,.~ \ '"

i5 ~ "~ .S

.... ... JJ, !i! i

~

N.... \(.... II; jl

I \ \ "" ,\, II

~

~,~

RIl

~lil..

.,....N\ II

~

.~

~il.",

\ "II'"II~,,,"II"II

~

~ ~ i ~ ~ ! i I § !SADO - ••,8.0 8urz ••,,, p.IDlnwn»"

15

"

~It:)

f &4(

'",§~I:j

§Ill: ~..,4( ~

:.t: ·S::e:~~

III I•... Cl)Cl)...

.g~

dllli'

z !j<0(...

~~..,~l~

~~~

~

~QQ'«

>0 ""Z .

'«

'"~.S'""

,

,,,

.- ~HEAN

, .f- ,/'

1973~("~......._.:'.

ALPENA, MICH • ~./.

.~

, /'::// .

,.1/

~.-~,I

-

, I

,...,...

•00

'100

lOCO

200

"V• \001-..!!::> 000E::>

"" ...c(

tit 2200>­o°2000•••... taOOIII•0: 160C

Cll

"•• 1111.00..••~ 1200

I-'Q\

S '0 IS 10 25 :tJ" S to I.i '" 2S 3l)" , 10 1.S ;x) 2$ 30' S JO 15 20 2:S • 5 lO tJ 20 25 J)' S J:) 1$ 20 2:S 30

NOV DEC JAN FEB MAR APR

Pigura A.a. Aocumu'Lat;ad fz'aeal,ng dagree-days - Laka Hla'(m at Al.pena. Miah.

,

.I

,

,

~_. . -''''''''. '"".. / . ~,DETROIT, KICH'7' .-....... CLEVELAND~'OH;;" ~IIEAN

, .//._../ ~.-<lm-J~ ._._..c.CLB EI.AIlD, OHIO IIEAN~

/" ~ ........-../ ........... ....

1200

2800

•

~

• ,GOO-II:> 100E:>

"" 600c(

'00

'00

)000

;. 2200

IIc_,••... '100III•Q 1600

Il2

"

2<00

260.

N ,.-00

••.t!-'....

S 10 LS 'a) u xf 5 10 l$ ~ :IS Xl' ! 1D 1$ 20 2.S )0' 5 10 15 20 :is • 5 10 lj 20 2S 30' S Xl 15 20 2'1 )()

NOV DEC JAN FEB MAR APR

Figu:.t'6 A.4. Aocwrru1.ated !reelling dsgree-c1IJ.ye - Lakes El'ie and St. Clair atC1.eveZa:nd, Ohio, and Detroit, Mich.

..

IIIIIII,,>o,.Z

Ilf

" 0(

"

"IDIII.....

IIII

II.. ~..

IIII

llZ.. ~..

~ ~ I ! ~ ~ ~ I I I ~dDQ - •••B.o- Burr•••:! p8jDlnlllnHV

yV1,/

/11"1.

A/ .....

1 "".. ....:z; \• \~ \

i \/

!

\\.~

". r\.~

\,

18

."C•'"•~

i ;;,Jl ~ ;;• <

~, • 3::.-l ;; • £: ~

.,:~ ~ ~,

E" •. • ~! • ~

< .-~-

. f' •• • :: .. r-. ·. fJ. ii ;;;, .~ <

; ·. • < j!~ o' "._0 ". '" .-~ -. " o~<

~2, ~.• · .:....~ -.0

0-~ • Si~

• ill ~ ~m~·

19

..;"-0,.....'<>...l'ooII}

=~:s!c: ~

l><~~ ~~

""l':.,>'tll':III

~IIIIII3I

~

~ij<I'l~.,>

I;:::;\t ~.,>

~12 .......

I"".-.:

~""....

G.

i ;;~~

;;, ;; ;;• < (:: £ , Ej~

j~

,E~ : >.

~ ~,., . • •;,of • " . • E~ • •·< • Z~ · •C..

'"..< .- · •~.

0 ~ ~M_ It- ,-,.

~;- G. li ~~

M.

;' o <i~.. O~

< • o~ " < "0· _0 o. 2: 0-< -~

~SM' · . ~~< ~ .. f- .. -~0 0 -~ · ,-2~Q

· m~ ~ ~ ~"

".~ ......... 0 •• " .

:::::::::::::::::0:'::::::::::::::

.: ::::iE::::::::.... . ............. " ." .. ".".""."" " " .. ".. " " .. " " .

: :::::: :::::::: :::::::::::: :::..... " ...... "... "." ... " "" " .. "...................... " ..l;:::::::::::::::::::::::::::::::"."." " " .."" " " ............ "."" .. "." " .. "" .

... 0" •••• "·"."." •• " " ••••••• o'"

::::::::::::::::::i~~~~~~~:::'

20

~0>.....,

">.,.,14III

'2~ill~."'1;j

Iii.>lIII

:1lI

""." .... " . ..,aii~.,.

.i~;S1C ~ll;!!I~~.":_ N

~ '"is. .... .::00: .... Cl

~•

"-...:IIIl4i5,.,.

f.<,

~CCl!ureli'Ii • 41T 98~ 110

legend

". cO .. t.""'.l"O~ (fUI.fll[ O"CfH-O.. ,

E:::!IA ~t."m"l.l«:1~

era!> "'tlH

w '" "ff~lr IQI,I

~1~3fl{)t'J.t'4at'

fitly OPIt<'l !1'd!l) I T '" ,,,,,,,,,1"11'."U~l~ Hntl

[[JJ] .. -ttl iQ (>,j"tuet(l1>P",,, .,.(1<;

N .. nOf",al

E:SS::3 '-9110 (he..... , ...m",l,!,••

l(IOUd PoKl<j ~Ull.11 101,1

~ W1IOCMlq. M .. m<l,,'1f'l1im, ((0"'01 PitH I

!i-':1Jl a..,, 63T 3lS• 361

"!ll,WAUKU

If :'::8I 1<;1;• 11lS

'... :::<~1jlmllll~rlllli~:.~"""""'''''''''''''~

:::u,,:i'illi@i':: ::::,,1·1,1',,111,1,1111~" 111m,'~~~~~~ : "'1~.'.~ . "":H:H""" ""Dul.un~

" 119I 693" 6'\

NI-'

"i G".<re A. ii. Corrrposite ice o'ha1't - lJJeek end:ing December 30, 1973.

22

•........">'"..'<>

r;;!!ii'!!I'

~~=-~a::

~...'1::.1f€

.-'<~

~J

'i>

aii~...

.J!...~

I.

'"•-.:

~.,.,II;,

i!mia3,a;:.-.

•z

f•

23

'"~

Figure A. 11.

&mit SA"W 211m" ISO

l'lIUtAI»:ElW• 11 III" q911

Composite iae chart - week ending January 20, 1974.

l&oend,,, Cont"rlln~Hlfl hUllng OeglU-o.y

EI:EJ.""ITU"II\IO(l

01110 ... It'W .. ""U~~Y 10tli

~1~3/IQt>(l¥t'~t

""'f OP'I'I l>"tllj T .. '"...... l't'vt....tt~lt H\U!

!IIlID .~!fiO.c.w,rll'"

(open 9M1o)N .. "l:!lm61

~1-9flO tcv~'liit '\lm"I .."".«(IO"~ Pk~}

",.."If IOUl

~ XVi(l tOrt,tt' M .. m•• ,mllll'l(to..,ol ~.tk)

:::ii!!WJJ!~!!U~:;;.;," ..:..t;~

!t¢CI1UH_• Sj;

i 343H J'll<

NI./l

Figupe A.12.

GRUN BAyV. 1&11791" 873

"IUWIKlEN 7T 539"589

Composite ice chart - !J)eek endingJcmuarry 27. 1974.

legendI" ConC.ntrallon F,tll'''1 O'I'n-Day

C2J "'C(\I,"I/I,l.on0"" _I'"W • Wllkly 101,1

~1-3/10 cow.r.,.(v"y ODlt! Pack) T • Cum"l.r, ••

wUklt 101.,[IT]] .-6/10 (,).... ,•••(op,,, PICk)

IN • "o,m'l

~ 1-91\0 cOver'll (1/"",,'.11 ....(C105'd PICk) • .,kly IOI.!

~ IOIJQ co....,... M • ", •• ,mum(cOI'llol PICk)

ROCHUTEJI, 21T 364H 361

'"0\

Du..UTM

W l~

1 1652H 1547

Figure A. 13.

Guilt bv• 911 mH 1012

I'llMAur:tl• il21 581H &J6

Composite ias chart - week ending February 3, 1974.

l eg&l"Id

'" ConCt'llltlOll frUtH'\1 D~£tet-D')'

c:::;]"'CCl.liT\\.dljfO~

O~" WIIU

W .. wU"ly ltlll~

I 1 1-3/)0 COI/U'i.hU)' op~, pICk} T .. c""'IoII'1''''

wH~ly tOI,!

([[]J] 4~Gl10 C\Wltt'.,

(\Sot'" pIck)til .. /"tOlrnll

~1~9110C6... I ••1 (um"l'hv'

(tlO"d ~k)w..~llI 101'1

~ lOIlO (Mt.I' M. /l'lUIIIIIlll'l{Cl)I\'bl Oltk I

RotWUTUW 2l1 liSN '16

'"....

DUl.UTH, 210T 18&2k 1686

Figure A.14. Composite ice chart - lJeek ending Feb:t'Uary 10, 1974.

legend

'" Co fI (; .,\1 rtllHIA 'tutti'll O,(,-.-Dly

E:J4(("/1'1,,,1.110"

OP'" w'l._Vi III- ..,nly tol,l

I i l~)/IG(O\ltrlfr;1

h.,t O'O,fl 111.(_) r .. t ...",.d.t!~

"'Uk" 1l~1'(

OJID] .~6/10 ¢~.,••'"Ia''' pat") /Ii .. "01"".1

~1-'11l) co....... (11"'1.1111<11'

(CIOUll P.tel<).....klf 101";

~ 10110 CO¥.(~g. M • "".',,",\,ll'l'l, (COIIwl onk l

RocHtnu, 1,1Tm, "99

'"co

DU\.UTIiW 1211 ISISIi lS3l.i

Figure A.16.

ul'UM BAyw lOST nIlS

" 1202

!'!1I.WAlla!W '12T 715

" all

Composite ioe ahart - week ending Februa:ty 17, 1974.

Legend

". COtH;al1trull)r' '''1111'1« O~Il(U-o.y

E::JAC(!JIl'1l,dihcn

O~(\ ... ltl

W • weekly 10111

~1-,H 10 UdI'i'{~'Y OP'lI I>IIO(iI) r '. (\lmultil ...'

wnUt lott'

lIIIITI .~6flO (¢Vl""-

(Op'lI pat"}~ • fIOrm.l

ESS3 1-9110 '0'11'('" ¢,,~I:IotII/'

Wo~,(l PKlt) w..kl~ I(lU!

~ 10/10 to",rl~' M • mUH1'Ium(cor-sol pJ;r;lt)

Roc:H£UUW 491 511, 514

iE§

, , 0; ~ ,.~ .. (:to,; • . f-':;

0';) ,E.; ; .u ,l', , .,,. •·. • z •'. ·"•

L.<,

?;;;'~ ," ~-· ,. "- "-· ~ G i ~ -. %:,;. • • §! ::; : • <

~ 2~! 2;' •

< -' f'~ ~lX ~-· • :..~ ,-0

· ill ~ ~ ~ ~·"

~".. ".... ...... .................~.....

29

f.<:I

~

~.,>

]'".0.::

~:3I

."ais~...~...

I

wo

uRU" eA'tV 7T 1218P 1318

MIl.WAUKlE¥ ·14T 163N m

lO\1eod

'" COt>e,l"dr.l,QfI I If_fl"'1 OteU.-O'1A tl::l'tTll,iI'l>Ql'I

EIJ §~{\ ·Uttr

W ., "'U'~ly 101 ...1

~~-3110 (Ovtr~.

{vtrY!l'Otll PKk} r .. (j,I"'h;"Il~t

,""Uo,lr 10111

[]]II] 4-61 to ,,,,,,,...lopu, ptek>

N .. 1'11)<1'1'1.,1

I§Sg 1- 'flO (Cd'fi' (.,tTI",l.t,,,,

{(lOUd PK1<l "U~~y !l:flJ'

"'IE~ 10110 CO'<trlgt III .. m.~,m~m

(COMal ~H1<J

Figw:oe A. 1? Composite ice chaxot - week ending Maxoch J, 1974.

~

I-'

Figure A. 18.

GIlUM BAyI ",n1 1lI~H 14n

KtL~t

I "561 10/H !lllII

COmp08ite ice chart - week ending March 10. 191'4.

ltgend

'" COl\t.filtt"I)"

I'ntt,MI Ct.ru-o.~

c::::JA«(""",,,I""Ol\

OPP _lit'

W .. "'."11 10lt,

~ 1·"""...... 1f,..'y Olafl PKIi) i .. (""''''11>.,

"'I\ly 101.,

[]]]] 4 A 6/10 (,)«,••'

{OP-,II 11.(1<1

I'" .. "Of"''''

~'~iIIO (!>v.,",t (\jm."I,U,.t

l(10WC~"1 ""'iii) IOUI

~ 1O1lO eOVtlalJf M .. "",.. ,m~m(COII(OI IUtl< I

Roc~uruIf • SqT l<aJ, 660

""""

bl£Eti: SAyV 21T l2llIl

" I"""

"1i.iiAUKU:V • 7, 700

" 946

legend

'" COn,.nt,.,IHH,\ I hUld'''a: 0«1,.. -011A(.C\lmllf,IIOl'l

E2J Gj)fl'l wlt.rW • wt~~Jr total

~1~3110 OC:O'lff'\lC{~Cfy open Ol(:~) r .. l:",m"llh~

WHkly I~U1

ITIIIIJ 4~6f 10 'v~~"i~

(O~tl\ pack)N .. normill

~1-9/101:0'1"". tlll'l'l\llillt"t

((llwe'.! """OJ .... Ukly 10:../

~~ll ~ JOIlO eOv,ralt M .. lI",UH'lIum

/? t,o~'Q<1 OUk)

ROCHuru• 71r 'i).;N 57l

Figure A.tO. Composite iae ahart - week ending Maroh 17, 1974.

""""

DvL"'", 1112T 2429M 2275

Figure A.20. Composite ice chart - week ending March 24, 1974.

legend

'" COfltf."t,hOll ~IUt"\' Ot('H_O.y

EJ.... C( .,"'''..1,1,.0''

CPt-II ""u_w· ..,HI, 10lt1

~1-31l0: C:O~"'k''''UI 011.'" p'Kkj t '"' ("'......I.!,~.

",Utlt 101,1

[]]]] '·6/10 c"",•.t(.(OlU", lin.)

k • 11(1"",,1

~1-'ilIO ((hlt't. e"m",I,I, ..fitlq~d Ilko, "u~lr IOU'

~ 10110 (O¥fU" • M "tr\lu,m"m{(0I'$01 p,n)

~O(:/otESr(., 78r 532M 654

""-

, '---.

.....,.

Figur'B A.21.

·::~ggnn.( ::::::::::::::::::~:;;:

II~ i; ~ ~~gH;~:;~ ~; ~ ~ ::'...... ~ ... ~ ...•. ~ ...

\\IIIII\\\\II\\\\ jr......

GUO lAyw 211 1lll9"" 1m

~tlw.uwW• 7T 142H'lIlIl

composite ioe ohart - week ending Marah 31, 1974.

Leg6nd

". coo<"'"'''' \rrtH"'l' DtjIU"'OU

c:;:JAt("m"ltH)1'l

ll-ptl"l ... ,tff w ....l/t1l1y loCil

~1~3i 10 eo~utke

(~tfy ~pt!'l IHKI.;JT .. (\lJT\ulllll~'

..... idy to,il

rrn:rn .~6'iO (¢.V'lt.t"(oll.n ~kJ

\N .. no/m. 1

&S31-9Jl0(C~'{~ll:'

¢vfl'Iulltw'

«loud P*C.~)

'd.~ly \ot. l

~ 10110 to.tt''ltM .. m'Hfl'l\l1l'l

~(QM.OI p.-<:k l

ROC:HU1U, II1 167HWl

< .- 0~.

~:;· ,.!:;-~:

o-

il -.- - U ~':i

< ; .. • • ..t~o· ".-. 2: 9.

~-. -. S!~· ~- r- ...

· . .. :.,': g;0 -" •

- 0~ ~ ~ ~

¢ • 0-; < • ~ . !o• ~~ -.- ,

:g -<- • ~

~h ~ei

l, ,

Ii" • ~ t ., 0 E<;;~:l

,

" • • •c . 1

•'"•

35

a " !~ .-, ;; ~§·. e~! ~!!:' .~~

~·. ! .. E::J;j0-; e- _E. •> • g><• E • •• ., f~ ~

v i • • z ~c•co•

i~~ • ~-~ : 5~ ;'~ c-· · > • n ~i•• • d· .. Od· , o' • < ..

e~· -. ~: 2:· • -~ ;O~ 0.£ o·· • -" ?i!' . , , .0 · -~ • --u

· m~ ~ ~ ~·

36

•""-

w.....

Gutll BAYV ·93, llUN 1222

~t~1:V • 9111 50'1• 618

SAuLT SU. l\ullV • 561 1W

" I1IlS

legend

'" (C1.H;,t>tttl,on ('HI"'\. O'fl,tU-O'1

E:::DA(tvl'!'I"l.j ~n

<.IP'~ ".IUIto' .. "Ul<ly lo1.el

~I~JIJO (PII""'"In'''' c"." /),,"j T •

'''''''''~j,~

""nUy tOI"l

ITIITIl 4-6./ICt~f'"

((lll .... 1»(_)N • ....ot<,o\,j

~7~9tIOtG!" •• oIt.t t",,,"1l11l'~'

(tfQU4lHK"l..tlll1y t(ll,,1

~ 10110 COWi'.' r.t '" ""'.''''''''11'1.. .. ltGl'\SOI Ptc .. t

ReCtl!SHR

W ·111, 219, JiQ

Figure A. 24. Composite ioe ohrnot - week ending ApriZ 21, 1974.

""00

Figure A.25.

fIIU.WAMl~ -1261318! 571

Composite ioe chart - lJJeek er,lding April. 28, 1914.

legend

." "., ..,.- \ FI.u'~, Ce&'U·-OI~

C3A,(UmvllhKit\

optn .. H"II> .. wU:l<.1oy IQUI

~lwJIlO ~O~Haile

{vHf cptI' pt(l<lr .. il:vm",lllll'le

wult1y l-Dlal

(J]]]]] ..... 6110 Cl)vtl."{of,lll'n )a('"

\

N. nor.rnlol

~, .. 9/ 10'(I'd'•••

(\ll'lWaI IV '

(('CU~ .k)....kl110UI

~ milO U4t.,tM _""tlUn'lllt'l'<

(tClI'ISOI p,e\< l

o

..

>­•L ..~_--- ~

%-=-.. :z:. ..o •...

~

o.!. e..;

.! •E ,.!! ;;.- .-'" ~

39

0'·

fHK I

Soull$t•. Mori.

~ SItIH< -.-

A S.Tti'i -.-

•E3 __

Kilometers,.Stolufe mile$

Fa Eri

2.

•

Figure A. 27. Whitefish Bay ioe ohart - l~oh 4, 1974.

40

•

•THIN

•0 ••

SHIP lIACE F-__

10 asH

Kilometer.

Hot oas

.$

10 ..''0

Siotute mil ••

o

20

10

Figure A.28. St. Marys River ice chaPt - December> 17, 1973.

41

..

A $.liii"' -.-

A ••THO -.-

,

_A_HUH

10Statute miles

20

,IS.

••

10Hri

o 10

Figure A.29. St. Ma:ry8 River ice chaPt - Ma:I'ah 4, 1974.

42

<,'

.,'

"

.8' .,'

J<.~lome'ent ... _

~ G ~ ~ ~

$to,ufe miles

..'

!.. ~

!... ....'

Figure A,30, Lake Michigan ice chart - Feb~ 27, 1974,

43

.,'

,,"

,,"

.,'

10 aSH

a,"A •• ~r-~

TH< -,-

Kilometers

a,"

.0

•

NOT 08S

88~ 87"~~~-~-~~~---T--~

' .... B

", " '" .. ~ -

LSlatute mile$

I Fi ... i

" I,

" '" I....' SI' H' e,"

4J'

,,"

.."

Figu:roe A. 31, Lake Michigan ice chart - March 4, 1974.

44

.0'

0" 0"

HOI 01$

oz'

..'

.,'I F3 F3'" .

E3•

Kilome.en

'" .. ..Slatu'e- miles

0.'

_A_ ~--'I--~~~~!':THIN 9

A S."'i'Hi"N -7---

eo ..to

.. ..0" oz'

I

-Lb.­MfO '0

..'

,,'

Figure A,32. Lake Huron ice cht:t.rt - February 25, 1974,

45

.4' B3' .,'

..'

2 aSH

lUH___J�i!-

Kilometers

'/'1•

017 --••

NOT 0"GoHrich

I F+i F"3"' .

20 "CI 10 60

StollJle mites

"' ..,..'

...,'

43"

Figure A,33, Lake Huron iae ahart - Feb~y 27, 1974.

46

....

3.' 3"

NO t 0.$

.r

.0'

Kilometf:ts! ... F3 !,. • ,. .. .. .. ...

.r Stotute miles .,'I .... .....,. • ,. .. ...,' .r .r

Figure A.34. Lake lIuron ice chart - Mtwch 4, 1974.

47

A 7KIlometers .. ..,

1MS 0 S$IQIUle mile$ S• CIOH.... ....

S 0 S A •THIN """i1O

C tACkS &:UAOS

Figure A.35.

Hew lolt;mote

L_-Ft.OOOING

LakE St. CZair ice chart - Feb1'UaI'Y 5, 1974.

48

.3

S 0

Statu If' ml If: SE'3S 0

S

S

_A ,_ ----teoJS s 110

Sf C loor

A •

SS 0"'0

_A__-l~~~IS

.,'

_A__'_

S S \20

-'-110

_A__'_

THIN ii'

Figure A. 36. Lake St. Clair ice ahart - Feb1"Ua:l'Y 25, 1974.

49

,,'

,,'

,..

, SoMEt) tiQi TO

~.

10

80'

A....~.I •

.,'

•Miii'"

.,' ..' !g'

::AL_'_ 8 '.... BO 017

A ~. A , S-

A ~ -, 1 (r·y; '--143'"i'i1"iN ---"I,A ~.

MTD -,-

..

..• 50

Ci"OT -,-

.,.

.,."

Ki lomeUfl

•

. ..Statute miles

83'

•MiO

,,'"

..

•00i"

A •

~ 009

A •

" 9 5" 1 _W SS '"iT?t"Hi"N CiTi -,- .... •'M'i'D

",

'"

U1o

Figu:t'e A, 37, Lake Erie ioe a'h(l1't - FooJ'Ua:t'Y 25. 1974,

.a ~

""r-..

'"....•~ ..

V);; ....= •~ El'! f

• ••E ,0

;; •>< .;;

~••

I

....• • {Jii..~( .....ee ].s'"~

cQt<)....;c

l!'£• ...%

"",.,,

-.

~

o%

..•o

M

f.>I~

;I~"'I~;.,

·1 ~ ~I~.:;I~

I

III

< :-

~I~I

<I!i'-

~I~1::

·I~

<I!

51

.~.