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Weekly Forecast

ARMY CORPS OF ENGINEERS WEEKLY GREAT LAKES WATER LEVEL UPDATE

Sep 17, 2021

 

WEATHER CONDITIONS

High temperatures ranged from mid-70's to upper 80's in central and southern basin. Chicago, IL to Detroit, MI region had high temperatures in low 80's to low 90's while Lake Superior basin high temperatures were in low 60's to mid-70's. Great Lakes basin received precipitation past week with areas in Michigan's upper peninsula and thumb region receiving near 3 inches. Abnormally dry conditions persist across south and central southern lower peninsula of Michigan with extreme drought in northern Minnesota and moderate drought to abnormally dry conditions across southern border of Lake Superior. Upcoming week high temperatures range in 60's to 80's in Lake Superior basin. Lake Michigan-Huron basin high temperatures forecast range in mid-70's to high 80's. High temperatures in Lake Erie and Lake Ontario basin forecasted for mid-70's to mid-80's. Forecasts predict a dry weekend across Great Lakes region with a chance of thunderstorms around Green Bay, WI and Milwaukee, WI leading into the weekend on Friday and showers near Buffalo, NY and Syracuse, NY. Dry conditions forecasted to persist through next week.

LAKE LEVEL CONDITIONS

Great Lakes water levels forecasted for September 17th are 1 to 6 inches below levels from a month ago and remain below last year’s levels. Lakes Michigan-Huron, St. Clair, and Erie remain well above their long-term average levels, while Lakes Superior and Ontario are within two inches of long-term average September levels. Great Lakes water levels typically decline during fall months. Projections for October 17th indicate water levels will decline by 1 inch on Lake Superior, 3 inches on Lake Michigan-Huron, 5 inches on Lake St. Clair and Lake Erie, and 3 inches on Lake Ontario. See our Daily Levels web page for more water level information.

FORECASTED MONTHLY OUTFLOWS/CHANNEL CONDITIONS

Predictions indicate Lake Superior’s outflow through the St. Marys River is below average in September. Forecasts show Lake Michigan-Huron’s outflow through St. Clair River and Lake St. Clair’s outflow into Detroit River are above average for September. Predictions show Lake Erie’s outflow into Niagara River is above average for September and forecasts say Lake Ontario’s outflow through St. Lawrence River is above average in September.

ALERTS

Water levels shown are still-water surface elevations over the entire lake surface. Water levels at specific locations may differ substantially due to meteorological influences. Official records are based on monthly average water levels and not daily water levels. Great Lakes, connecting channels and St. Lawrence River users should keep informed of current conditions before undertaking any activities affected by changing water levels. Mariners should utilize navigation charts and refer to current water level readings.

SUPERIOR

MICH-HURON

ST. CLAIR

ERIE

ONTARIO

Forecasted Water Level for Sep 17, 2021 (feet)

602.07

580.51

576.12

573.00

245.37

Chart Datum (feet)

601.10

577.50

572.30

569.20

243.30

Difference from chart datum (inches)

+12

+36

+46

+46

+25

Difference from average water level for Aug 17, 2021 (inches*)

-1

-3

-5

-6

-2

Difference from average water level for Sep 17, 2020 (inches*)

-11

-16

-11

-7

-2

Difference from long-term monthly average of Sep (inches)

-1

+16

+19

+18

+2

Difference from highest monthly average of record for Sep (inches)

-14

-17

-11

-9

-24

Year of highest recorded monthly mean

2019

1986

2020

2019

1947

Difference from lowest monthly average of record for Sep (inches)

+19

+46

+50

+50

+35

Year of lowest recorded monthly mean

2007

1964

1934

1934

1934

Projected net change in levels by Oct 17, 2021 (inches)

-1

-3

-5

-5

-3

ALL DATA SHOWN IN THIS SUMMARY ARE REFERENCED TO IGLD 1985

*VALUES FOR SPECIFIC DAY ARE BASED ON 3-DAY DAILY AVERAGE AROUND SPECIFIED DATE

LONG TERM AVERAGE PERIOD OF RECORD, 1918-2020

FORECASTED INFORMATION PROVIDED BY

RECORDED DATA (1918 – present)

FOR MORE INFORMATION VISIT

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Weekly Great Lakes Water Levels

We do not have the ability to offer email updates at this time.  The Weekly Forecast of Great Lakes Water Levels is updated each week on Thursday afternoon or Friday morning depending on data availability.

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Detroit District Disclaimer

NOTICE: All data contained herein is preliminary in nature and therefore subject to change. The data is for general information purposes ONLY and SHALL NOT be used in technical applications such as, but not limited to, studies or designs. All critical data should be obtained from and verified by the United States Army Corps of Engineers, Detroit District, Engineering and Technical Services, Great Lakes Hydraulics and Hydrology Office, 477 Michigan Ave., Detroit, MI 48226. The United States of America assumes no liability for the completeness or accuracy of the data contained herein and any use of such data inconsistent with this disclaimer shall be solely at the risk of the user.