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Weekly Forecast

ARMY CORPS OF ENGINEERS WEEKLY GREAT LAKES WATER LEVEL UPDATE

Oct 30, 2020

 

WEATHER CONDITIONS

For the month of October, Lakes Superior and Michigan-Huron has received approximately 20% above average precipitation.  Over the past week, most of the Great Lakes Basin received typical precipitation for this time of the year.  Marquette, Michigan received 8 inches of snow on Sunday, October 25 and 2 inches of snow on Monday, October 26, bringing October's total snowfall in the city to a record high 21.2 inches. Some precipitation will accompany a low pressure, cold front across the region for Thursday, October 29 into Friday, October 30.  A high-pressure system will begin moving west to east over the basin Saturday, followed Sunday by a cold front, with chilly temperatures and little to no precipitation expected.  As the cold front moves out early next week, temperatures are forecasted to rise across the basin.

LAKE LEVEL CONDITIONS

All the lakes continue in their period of seasonal decline.  The October 30th predicted levels are all below last month's levels.   Additionally, all of Friday's levels are expected to be at or below 2019 levels.  Lake Erie's forecasted level is approximately the same as its October 30th level of one year ago, while Lakes Superior, Michigan-Huron, St. Clair, and Ontario forecasted levels are expected to be about 6, 1, 2, and 15 inches below their 2019 level, respectively.  All lakes remain above their long-term monthly average October levels, but below their record high October average levels. By November 30th, water levels are projected to decline 3 inches on Lakes Superior and Michigan-Huron and to decline 4 inches on Lakes St. Clair and Erie.  Lake Ontario is projected to decline 2 inches in the next month.  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 October. Also, Lake St. Clair’s outflow into the Detroit River is predicted to be above average for October. Lake Erie’s outflow into the Niagara River is predicted to be above average for October. Moreover, Lake Ontario’s outflow into the St. Lawrence River is predicted to be above average this October.

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 Oct 30, 2020 (feet)

602.79

581.53

576.51

573.16

244.95

Chart Datum (feet)

601.10

577.50

572.30

569.20

243.30

Difference from chart datum (inches)

+20

+48

+51

+48

+20

Difference from average water level for Sep 30, 2020 (inches*)

-2

-2

-2

-2

-4

Difference from average water level for Oct 30, 2019 (inches*)

-6

-1

-2

0

-15

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

+8

+31

+28

+24

+2

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

-7

-10

-9

-9

-22

Year of highest recorded monthly mean

1985

1986

1986

1986

1945

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

+25

+61

+57

+55

+33

Year of lowest recorded monthly mean

1925

1964

1934

1934

1934

Projected net change in levels by Nov 30, 2020 (inches)

-3

-3

-4

-4

-2

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.