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Weekly Forecast

ARMY CORPS OF ENGINEERS WEEKLY GREAT LAKES WATER LEVEL UPDATE

Jul 10, 2020

 

WEATHER CONDITIONS

Over the holiday weekend, temperatures were above average for the entire Great Lakes with some of the upper Great Lakes region being more than 8°F above normal for this time of year. Persistent hot conditions with relatively high humidity have continued for the area through most of the work week. With this, it has been relatively dry for the area since the beginning of the month, with some convective type thunderstorms hitting pockets of the region. Looking forward, showers and/or thunderstorms developing Thursday evening over Lake Michigan are expected to impact most of the region over the weekend. Predictions indicate that most of the area, with the exception of the Lake Superior basin will receive anywhere from 0.5”-2.0” of rain by Sunday morning. A return to hot and humid conditions is expected for the region early next week.

LAKE LEVEL CONDITIONS

Lake Superior’s July 10th forecasted level is 5 inches below its level of a year ago, with the July 10th forecasted level for Lake Michigan-Huron 3 inches higher than last year’s level. The projected levels of Lakes St. Clair and Erie for July 10th are 1 and 4 inches below what they were a year ago. Lake Ontario’s July 10th predicted level is 24 inches below its level of a year ago. The projected levels for July 10th set of tie existing July monthly mean records for two lakes. The projected level for Lake Michigan-Huron is around 2 inches above its July monthly record, while the projected level of Lake St. Clair matches its record high monthly level. On August 10th, Lake Superior is predicted to be an inch higher than its projected level for July 10th. In contrast, August 10th levels for Lakes Michigan-Huron, St. Clair, Erie, and Ontario are predicted to be below their July 3rd expected levels by 1, 3, 3, and 3 inches, respectively. See our Daily Levels web page for more water level information.

FORECASTED MONTHLY OUTFLOWS/CHANNEL CONDITIONS

Lake Superior’s outflow into the St. Mary’s River and Lake Michigan-Huron’s outflow into the St. Clair River are predicted to be above average in July. Lake St. Clair’s outflow through the Detroit River and Lake Erie’s outflow into the Niagara River are forecasted to be above average in July. Moreover, the outflow of Lake Ontario into the St. Lawrence River are projected to be above average for July.

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 Jul 10, 2020 (feet)

602.76

582.15

577.53

574.28

246.72

Chart Datum (feet)

601.10

577.50

572.30

569.20

243.30

Difference from chart datum (inches)

+20

+56

+63

+61

+41

Difference from average water level for Jun 10, 2020 (inches*)

+1

0

+2

-2

-5

Difference from average water level for Jul 10, 2019 (inches*)

-5

+3

-1

-4

-24

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

+8

+33

+32

+28

+7

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

-6

+2

0

-4

-24

Year of highest recorded monthly mean

2019

1986

2019

2019

2019

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

+30

+65

+60

+63

+42

Year of lowest recorded monthly mean

1926

1964

1934

1934

1934

Projected net change in levels by Aug 10, 2020 (inches)

+1

-1

-3

-3

-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, 1918-2019

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.