ARMY CORPS OF ENGINEERS WEEKLY GREAT LAKES WATER LEVEL UPDATE

May 17, 2024

WEATHER CONDITIONS

The Great Lakes Basin received a lot of rain this week, following the thunderstorms experienced across the majority of the basin earlier this week. Lake Superior was on the drier side, experiencing around 0.1 inches of rain. Lakes Michigan-Huron and Ontario received an average of around half an inch, with Erie receiving about an inch of rain. The basin experienced near average temperatures this past week. Looking forward, rain and thunderstorms are expected across the basin Friday into Saturday and possibly into next week. Temperatures can be expected to be well above average this weekend into next week, with most of the basin expected to experience upwards of 80 degrees Fahrenheit.

LAKE LEVEL CONDITIONS

The forecasted lake levels for May 17^th indicate all lakes have risen since last month by 1 to 5 inches. All of the lakes are below levels from a year ago. Lake Michigan-Huron, Lake St. Clair, Lake Erie are 4, 2, and 1 inches below where they were last year, respectively. Lakes Superior and Ontario are 13 and 17 inches below last year and are 2 and 3 inches below their long-term May monthly averages. Lakes Michigan-Huron, St. Clair, and Erie are above their long-term monthly averages, at 3, 10, and 11 inches, respectively. Even though some of the lakes are below their long-term monthly averages, all lakes are still well above their record low water levels for May. Next month all lakes are expected to rise between 1 and 3 inches, except for Lake Erie which is expected to stay near the same. For more information, please see our Daily Levels web page.

FORECASTED MONTHLY OUTFLOWS/CHANNEL CONDITIONS

Lake Superior’s outflow into the St. Marys River is expected to be slightly below average for May.  Lake Michigan-Huron’s outflow through the St. Clair River and Lake St. Clair’s outflow into the Detroit River are projected to be slightly above average for May. Lake Erie’s outflow through the Niagara River, and Lake Ontario’s outflow from the St. Lawrence River are projected to be above average in May.

ALERTS

Water levels shown are still-water surface elevations over the entire lake surface. Water levels at specific locations may differ due to meteorological influences. Official records are based on monthly average water levels and not daily water levels. Great Lakes, connecting channels, and St. Lawrence River users should keep informed of current conditions before undertaking any activities affected by changing water levels. Mariners should use navigation charts and refer to current water level readings. Find ice information at National Ice Center’s website.

SUPERIOR

MICH-HURON

ST. CLAIR

ERIE

ONTARIO

Forecasted Water Level for May 17, 2024 (feet)

601.48

579.36

575.49

572.93

245.93

Chart Datum (feet)

601.10

577.50

572.30

569.20

243.30

Difference from chart datum (inches)

+5

+22

+38

+45

+32

Difference from average water level for Apr 17, 2024 (inches*)

+4

+5

+2

+1

+2

Difference from average water level for May 17, 2023 (inches*)

-13

-4

-2

-1

-17

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

-2

+3

+10

+11

-3

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

-17

-31

-22

-18

-33

Year of highest recorded monthly mean

2019

2020

2020

2020

2017

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

+22

+33

+39

+47

+33

Year of lowest recorded monthly mean

1926

1964

1934

1934

1935

Projected net change in levels by Jun 17, 2024 (inches)

+3

+2

+1

0

+1

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, 1918-2023

FORECASTED INFORMATION PROVIDED BY

RECORDED DATA (1918 – present)

FOR MORE INFORMATION VISIT

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