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Weekly Forecast

ARMY CORPS OF ENGINEERS WEEKLY GREAT LAKES WATER LEVEL UPDATE

Sep 18, 2020

 

       

WEATHER CONDITIONS

Wet weather moved in over the weekend from the southwest-west moving east across the basin. The Upper Peninsula of Michigan received a half to one and a half inches higher than average rainfall over the past week. Temperatures are forecasted below average for most of the basin into the weekend and will warm to slightly above average temperatures by the middle of next week with most of the basin seeing sunny to partly sunny conditions. Northern portions of the basin including Lake Superior south through the Upper Peninsula are forecasted to receive up to a quarter of an inch of precipitation from Monday through next Thursday.

LAKE LEVEL CONDITIONS

The September 18th predicted levels are all at or below last month’s levels. The projected September 18th levels are also below levels from last year on Lakes Superior, Erie, and Ontario. While on Lakes Michigan-Huron and St. Clair, forecasted September 18th water levels are at or 2 inches above levels of a year ago. The predicted September 18th levels are also above the September monthly average water levels on all lakes. Lake St. Clair’s September 18th water level is at its highest monthly average water level for September. All lakes are forecast to decline in the coming month. Lake Superior is forecast to be one inch below its September 18th level, while the levels of Lakes Michigan-Huron, St. Clair, Erie, and Ontario are predicted to decline by 3 to 7 inches from their projected September 18th levels. See our Daily Levels web page for more water level information.

FORECASTED MONTHLY OUTFLOWS/CHANNEL CONDITIONS

Lake Superior’s outflow through the St. Mary’s River and Lake Michigan-Huron’s outflow through the St. Clair River are projected to be above average in September. Also, Lake St. Clair’s outflow into the Detroit River is predicted to be above average for September. Lake Erie’s outflow into the Niagara River is predicted to be above its record September outflow this month. Moreover, Lake Ontario’s outflow into the St. Lawrence River is predicted to be above average this 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. Users of the Great Lakes, connecting channels and St. Lawrence River should keep informed of current conditions before undertaking any activities that could be affected by changing water levels. Mariners should utilize navigation charts and refer to current water level readings. High water levels and potentially record high water levels are expected to persist for at least the next six months, so flood prone areas are expected to remain vulnerable.

SUPERIOR

MICH-HURON

ST. CLAIR

ERIE

ONTARIO

Forecasted Water Level for Sep 18, 2020 (feet)

603.02

581.86

576.97

573.59

245.57

Chart Datum (feet)

601.10

577.50

572.30

569.20

243.30

Difference from chart datum (inches)

+23

+52

+56

+53

+27

Difference from average water level for Aug 18, 2020 (inches*)

0

-3

-4

-4

-7

Difference from average water level for Sep 18, 2019 (inches*)

-2

+2

0

-2

-15

 

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

+10

+33

+30

+26

+4

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

-2

-1

0

-2

-22

Year of highest recorded monthly mean

2019

1986

2019

2019

1947

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

+31

+63

+60

+57

+37

Year of lowest recorded monthly mean

2007

1964

1934

1934

1934

 

Projected net change in levels by Oct 18, 2020 (inches)

-1

-3

-5

-5

-7

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, 1918-2019

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.