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Weekly Forecast

ARMY CORPS OF ENGINEERS WEEKLY GREAT LAKES WATER LEVEL UPDATE

Apr 16, 2021

 

WEATHER CONDITIONS

The Great Lakes basin experienced much reduced temperatures over the past week following a very warm week prior. Precipitation in the Lake Superior Basin is currently almost double its average April rainfall, while the rest of the basin continues to remain well below the monthly average. Near average temperatures are expected to continue in the coming week, and some precipitation is expected to move through the basin over the weekend as well.

LAKE LEVEL CONDITIONS

The projected water levels for April 16th indicate that Lake St. Clair will be near its average level from a month ago, while all other lakes will experience levels 1 to 5 inches above their levels of a month ago. Forecasted April 16th levels also show that all lakes continue to track below levels from a year ago. However, projected levels for April 16th indicate that water levels are above long-term April average levels on all lakes, except Lake Ontario. Projections show rises in water levels from 2 to 7 inches for all lakes over the next month as spring weather continues to influence the basin. See our Daily Levels web page for more water level information.

FORECASTED MONTHLY OUTFLOWS/CHANNEL CONDITIONS

Lake Superior’s outflow through the St. Marys River is predicted to be average this April. Lake Michigan-Huron’s outflow through the St. Clair River and Lake St. Clair’s outflow into the Detroit River are forecasted to be above average for April. Lake Erie’s outflow into the Niagara River is predicted to be above average for April and Lake Ontario’s outflow through the St. Lawrence River is projected to be above average in April.

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 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 Apr 16, 2021 (feet)

602.03

580.61

575.95

572.97

244.78

Chart Datum (feet)

601.10

577.50

572.30

569.20

243.30

Difference from chart datum (inches)

+11

+37

+44

+45

+18

Difference from average water level for Mar 16, 2021 (inches*)

+4

+1

0

+2

+5

Difference from average water level for Apr 16, 2020 (inches*)

-5

-13

-13

-17

-29

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

+9

+22

+19

+16

-11

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

-7

-13

-14

-16

-41

Year of highest recorded monthly mean

1986

2020

2020

2020

1973

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

+31

+54

+48

+50

+23

Year of lowest recorded monthly mean

1926

1964

1926

1934

1935

Projected net change in levels by May 16, 2021 (inches)

+3

+2

+3

+3

+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, 1918-2020

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.