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Weekly Great Lakes Water Levels

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Weekly Forecast

WEEKLY GREAT LAKES WATER LEVEL UPDATE

April 17, 2015

 

WEATHER CONDITIONS

Storms brought heavy precipitation over much of the basin last Thursday, and high wind and periods of rain persisted on Friday. Last week’s rainfall brought many Great Lakes tributaries back to normal or above normal flow. Skies cleared and brought freezing temperatures across much of the basin Friday night, but daytime temperatures reached into the upper 60s and low 70s by Monday. Despite some snowmelt which further increased flow in Michigan’s Upper Penninsula’s streams, snowpack lingers over the northeastern portion of the Superior basin and the northern portion of the Lake Huron basin. Warm temperatures will continue through Saturday, but temperatures will cool somewhat by Sunday. Highs ranging from the upper 30s to upper 50s across the basin are forecast by Wednesday. Some precipitation is expected over the eastern portion of the basin Friday morning and then again on Sunday and lingering through Tuesday across the basin. Over the next seven days, total rainfall amounts of 0.5 inch in the north to over 1 inch in the southern portion are expected.

LAKE LEVEL CONDITIONS

Lakes Superior and Michigan-Huron are 7 and 18 inches, respectively, above their levels of a year ago. Lake St. Clair is 9 inches above last year’s level, and Lake Erie is just one inch above its level of a year ago. Lake Ontario is 11 inches below what it was at this time last year. Lakes Superior and Michigan-Huron are predicted to rise 3 inches over the next month. Lakes St. Clair and Erie are forecast to rise 4 inches, and Lake Ontario is expected to rise 9 inches over the coming 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 is forecasted to be above average for the month of April. Lake Michigan-Huron’s outflow into the St. Clair River and Lake St. Clair’s outflow into the Detroit River are predicted to be above average in April. The April outflow of Lake Erie into the Niagara River is forecast to be near average, but Lake Ontario’s outflow into the St. Lawrence River is predicted to be less than average in April.

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. Ice information can be found at the National Ice Center’s website.

SUPERIOR

MICH-HURON

ST. CLAIR

ERIE

ONTARIO

Forecasted Water Level for Apr 17, 2015 (feet)

601.84

579.2

574.84

571.78

244.85

Chart Datum (feet)

601.10

577.50

572.30

569.20

243.30

Difference from chart datum (inches)

+9

+20

+30

+31

+19

Difference from average water level for Mar 17, 2015 (inches*)

0

+2

+7

+11

+9

Difference from average water level for Apr 17, 2014 (inches*)

+7

+18

+9

+1

-11

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

+7

+7

+7

+2

-10

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

-9

-27

-24

-28

-40

Year of highest recorded monthly mean

1986

1986

1986

1985

1973

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

+28

+37

+35

+35

+24

Year of lowest recorded monthly mean

1926

1964

1926

1934

1935

Projected change in levels by May 17, 2015 (inches)

+3

+3

+4

+4

+9

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, 1918-2014

FORECASTED INFORMATION PROVIDED BY

RECORDED DATA (1918 – present)

FOR MORE INFORMATION VISIT

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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.