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Weekly Great Lakes Water Levels

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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.

Weekly Forecast

ARMY CORPS OF ENGINEERS WEEKLY GREAT LAKES WATER LEVEL UPDATE

Aug 17, 2018

 

WEATHER CONDITIONS

Over the past week, August temperatures have generally been a few degrees above average for the Great Lakes basin.  For the most part, the past week has been dry, and over the weekend many regions can expect sunshine and daily highs in the 80’s in many cities across the basin such as Green Bay, WI, Detroit, MI and Buffalo, NY.  In the coming week, a low pressure system is expected to move northwest across the entire basin.  Precipitation is likely to start falling Tuesday in the form of showers and thunderstorms, arriving to Chicago, IL by early afternoon Tuesday and reaching Syracuse, NY the same day, with precipitation due to continue through the night into Wednesday.

LAKE LEVEL CONDITIONS

All of the Great Lakes remain above their long-term average levels. Lakes Superior, Michigan-Huron and St. Clair are 5, 2, and 1 inch, respectively, below their level of one year ago. Lake Erie is 1 inch above last year’s level, and Lake Ontario is 20 inches below its level of last year. Over the past week, Lake Superior levels have plateaued, while the other lakes have continued on with their seasonal decline.  Since the previous month, lake Michigan-Huron has fallen 1 inch, both lake St. Clair and lake Erie have fallen 3 inches and lake Ontario has fallen 6 inches.  Over the next 30 days, Lake Superior is expected to be near its current level, while Lakes Michigan-Huron, St. Clair, Erie, and Ontario are forecast to fall by 2, 3, 5, and 7 inches, respectively. 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 and Lake Michigan-Huron’s outflow into the St. Clair River are projected to be above average in August. Lake St. Clair’s outflow through the Detroit River and Lake Erie’s outflow through the Niagara River are also forecasted to be above average.  In addition, Lake Ontario’s outflow through the St. Lawrence River is predicted to be above average for August.

ALERTS

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.

SUPERIOR

MICH-HURON

ST. CLAIR

ERIE

ONTARIO

Forecasted Water Level for Aug 17, 2018 (feet)

602.56

580.54

576.21

573.26

245.77

Chart Datum (feet)

601.10

577.50

572.30

569.20

243.30

Difference from chart datum (inches)

+18

+36

+47

+49

+30

Difference from average water level for Jul 17, 2018 (inches*)

0

-1

-3

-3

-6

Difference from average water level for Aug 17, 2017 (inches*)

-5

-2

-1

+1

-20

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

+5

+15

+19

+19

+1

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

-8

-17

-11

-8

-26

Year of highest recorded monthly mean

1952

1986

1986

1986

1947

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

26

46

48

51

36

Year of lowest recorded monthly mean

2007

1964

1934

1934

1934

Projected change in levels by Sep 17, 2018 (inches)

0

-2

-3

-5

-6

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, 1918-2017

FORECASTED INFORMATION PROVIDED BY

RECORDED DATA (1918 – present)

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