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Weekly Great Lakes Water Levels

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Weekly Forecast

ARMY CORPS OF ENGINEERS WEEKLY GREAT LAKES WATER LEVEL UPDATE

May 18, 2018

 

WEATHER CONDITIONS

After a cooler than normal weekend, temperatures were above normal for most of the Great Lakes basin this past week. A band of heavy rains passed through much of the southern Great Lakes Basin earlier this past week causing localized flooding incidents throughout the region. A cold front moved through the basin Thursday and Friday bringing temperatures back to near normal throughout the basin for this weekend. Along with cooler temperatures, the front will also bring light rain to a majority of the basin Saturday and Sunday. Looking ahead to next week, near average temperatures will persist for most of the Great Lakes basin, except for areas near the Lake Superior basin which are expected to see above normal temperatures. There is also another chance for rain in the middle of the upcoming week for the southern part of the Great Lakes basin.

LAKE LEVEL CONDITIONS

The Great Lakes water levels are all above their long-term average May levels. Lake Superior is 2 inches lower than it was at this time last year, while lakes Michigan-Huron, St.Clair, and Erie are 5, 6, and 3 inches respectively, above last year’s levels and Lake Ontario is 23 inches below its level from a year ago. Lake Erie is 3 inches below its highest monthly average for May while Lake Ontario is 20 inches below its record monthly high water level for May (note that daily levels can vary substantially during the month). Over the next 30 days, Lake Superior, and Lake Michigan-Huron are projected to rise 3 inches each, Lake St. Clair and Lake Erie are forecasted to drop 1 inch, and Lake Ontario is expected to drop 2 inches. 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 through the St. Clair River are forecasted to be above average in May. Lake St. Clair’s outflow through the Detroit River and Lake Erie’s outflow into the Niagara River are also projected to be above average The outflow of Lake Ontario into the St. Lawrence River is predicted to be above average for May as well.

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 May 18, 2018 (feet)

602.07

580.48

576.57

573.82

246.98

Chart Datum (feet)

601.10

577.50

572.30

569.20

243.30

Difference from chart datum (inches)

+12

+36

+51

+55

+44

Difference from average water level for Apr 18, 2018 (inches*)

+2

+5

+2

+3

+9

Difference from average water level for May 18, 2017 (inches*)

-2

+5

+6

+3

-23

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

+6

+18

+24

+23

+10

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

-9

-14

-4

-3

-20

Year of highest recorded monthly mean

1986

1986

1986

1986

2017

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

30

47

52

57

46

Year of lowest recorded monthly mean

1926

1964

1934

1934

1935

Projected change in levels by Jun 18, 2018 (inches)

+3

+3

-1

-1

-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, 1918-2017

FORECASTED INFORMATION PROVIDED BY

RECORDED DATA (1918 – present)

FOR MORE INFORMATION VISIT

Department of the Army

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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.