ARMY CORPS OF ENGINEERS WEEKLY GREAT LAKES WATER LEVEL UPDATE

Mar 17, 2023

WEATHER CONDITIONS

Air temperatures across the Great Lakes basin last weekend and into this work week were below average before warming to near average mid-week. Forecasted temperatures heading into the coming weekend across the entire basin appear to again dip below average before returning to near average in mid-to-late next week. Much of the basin received precipitation over the past week with total accumulations reaching up to 1.5 inches across Milwaukee, WI and Grand Rapids, MI regions. A particular system brought a mix of rain and snow across Wisconsin and southern Michigan heading into last weekend. Wet conditions are forecast across the entire Great Lakes basin heading into and throughout the coming weekend before returning to drier conditions beginning next work week. Lake Erie and Ontario basins have another chance for wet weather mid to late next week. Ice formation on the Great Lakes continues to be below average given above average water temperatures.

LAKE LEVEL CONDITIONS

The predicted March 17th water level for Lake Superior is 2 inches below of its level a month ago. Lakes Michigan-Huron and Ontario are 1 and 2 inches above their levels of a month ago, while Lakes St. Clair and Erie are 4 and 8 inches above their levels of a month ago. The projected water level for March 17^th for Lake Superior is 11 inches above what it was a year ago and, while Lakes Michigan-Huron, St. Clair and Ontario are 3, 1, and 5 inches below their levels from a year ago. Lake Erie’s forecasted March 17th level is 2 inches above its level from last year. All the lakes are above their March long-term average levels. During the next 30 days, Lakes Superior, Michigan-Huron, St. Clair, Erie, and Ontario are expected to rise 1, 3, 4, 3, and 5 inches, respectively. See our Daily Levels web page for more water level information.

FORECASTED MONTHLY OUTFLOWS/CHANNEL CONDITIONS

Lake Superior’s outflow through St. Marys River and Lake Michigan-Huron’s outflow through St. Clair River are forecasted to be above average for March. Lake St. Clair outflow through Detroit River, Lake Erie outflow through Niagara River, and Lake Ontario outflow through the St. Lawrence River are projected to be above average in March as well.

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 Mar 17, 2023 (feet)

601.80

578.87

575.10

572.70

245.57

Chart Datum (feet)

601.10

577.50

572.30

569.20

243.30

Difference from chart datum (inches)

+8

+16

+34

+42

+27

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

-2

+1

+4

+8

+2

Difference from average water level for Mar 17, 2022 (inches*)

+11

-3

-1

+2

-5

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

+7

+5

+14

+18

+6

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

-7

-31

-21

-15

-20

Year of highest recorded monthly mean

1986

2020

2020

2020

1952

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

+27

+34

+49

+54

+36

Year of lowest recorded monthly mean

1926

1964

1934

1934

1935

Projected net change in levels by Apr 17, 2023 (inches)

+1

+3

+4

+3

+5

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, 1918-2021

FORECASTED INFORMATION PROVIDED BY

RECORDED DATA (1918 – present)

FOR MORE INFORMATION VISIT

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