ARMY CORPS OF ENGINEERS WEEKLY GREAT LAKES WATER LEVEL UPDATE

May 10, 2024

WEATHER CONDITIONS

Above normal temperatures existed throughout the Great Lakes basin over much of the past week. However, as the work week comes to an end some cooler air has ushered into the region. This will be short lived with a warming trend likely toward the end of the weekend and into early next week. Overall, precipitation for the start of May has been near average across the Great Lakes region. The southern Lake Michigan basin experienced severe weather on Tuesday evening as an EF-2 tornado was reported in Portage, Michigan, while additional tornadoes, hail, and strong winds also impacted this area. A couple rounds of rain showers and possible thunderstorms are forecast through the weekend and into the work week as multiple frontal systems cross the Great Lakes region.

LAKE LEVEL CONDITIONS

The forecasted lake levels for May 10^th indicate all lakes have risen since last month by 4 to 6 inches. Compared to last year, all the lakes are below levels from a year ago. Ranging from 1 to 4 inches below last year on Lakes Michigan-Huron, St. Clair, and Erie, while Lakes Superior and Ontario are 13 and 17 inches below last year’s levels, respectively.  The projected May 10^th water levels are above their May long-term average levels on Lakes Michigan-Huron, St. Clair, and Erie, whereas Lakes Superior and Ontario are below their May average levels by 2 to 3 inches. By next month, Lakes Superior, Michigan-Huron, and Ontario are forecast to rise by 2 to 3 inches, Lake St. Clair is projected to rise 1 inch, and Lake Erie is expected to remain near its current level. 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 10, 2024 (feet)

601.48

579.33

575.46

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 10, 2024 (inches*)

+4

+6

+6

+5

+6

Difference from average water level for May 10, 2023 (inches*)

-13

-4

-2

-1

-17

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

-2

+3

+9

+11

-3

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

-17

-31

-23

-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 10, 2024 (inches)

+3

+3

+1

0

+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, 1918-2023

FORECASTED INFORMATION PROVIDED BY

RECORDED DATA (1918 – present)

FOR MORE INFORMATION VISIT

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