FZUS81 KCLE 141651
ICEGL
GREAT LAKES ICE BREAK-UP OUTLOOK
NATIONAL WEATHER SERVICE CLEVELAND OH
1253 PM EDT Fri Mar 14 2025
...Maximum Ice Coverage for the 2024-2025 season briefly reached
average, but was below average on the whole...
The strong El Nino from the 2023-2024 ice season transitioned to
neutral conditions late Summer/early Fall of 2024, and then to weak
La Nina into the winter of 2024-2025. Using data from past strong El
Nino to weak La Nina events and the resultant ice coverage, the
trend was for below normal ice coverage, which was a main component
of the forecast this past Fall along with the one month and three
month outlooks provided by the Climate Prediction Center.
Ice coverage peaked at 52.23 percent on February 21st. The running
average maximum ice coverage for the Great Lakes since the early
1970s is 52 percent.
Looking back at the weather summaries over the season, December was
slightly warmer than normal (generally 1-3F) across the entirety of
the Great Lakes, while January and February both trended slightly
below normal (generally 1-4F). The second half of December was the
milder portion of that month, and this did serve to delay ice
formation of any significance. It also needs to be recalled that
water temperatures were still riding well above normal at that time,
carrying over from those conditions from the Fall season, and ice
formation was ultimately pushed to 2025. January and February were
largely characteristic of frequent cold airmasses over the Great
Lakes with limited and brief temperature recoveries to near or above
freezing values. The typical areas in the Great Lakes froze
first...the western basin of Lake Erie, Green Bay/Big Bay de
Noc/Little Bay de Noc, Saginaw Bay, St. Marys River, and Lake St.
Clair. In January, the southern Great Lakes were more significantly
colder than normal with Cleveland the outlier at 5.6F below normal
for the month and Toledo at 3.7F below normal. Lake Erie froze
nearly completely, and had at least 80 percent ice coverage from the
end of January through the end of February, peaking around 95
percent in mid February. But the Great Lakes on the whole were
fairly windy over the January through February period, and on Lake
Erie, the ice was frequently pushed around with very little dominant
fast ice. Eventually, Whitefish Bay and the Straits of Mackinac
froze over with extensive fast ice into February. Open water regions
of the other Great Lakes outside of Erie saw very little ice, and
the water temperatures there had trouble getting below the upper
30s. Satellite derived water temperatures in the open waters of
northern Lake Huron in late January into early February were still
peaking around 40F. Further to the north and west, much of Duluth
Harbor remained ice free. Shoreline ice was present in many areas of
the lakes, but not extensive. For the open waters outside of Lake
Erie, it is believed that persistently windy conditions in January
and February did play a role inhibiting ice formation.
FREEZING DEGREE DAY ACCUMULATIONS AT SELECTED STATIONS
COMPARED TO NORMAL CALCULATED ON Thu Mar 13:
LOCATION DATE NORMAL CURRENT
----------------------------------------
DULUTH, MN MAR 12 1768 1760
MARQUETTE, MI MAR 12 1556 1448
SAU_S_MAR, MI MAR 12 1257 1118
GREENBAY, WI MAR 12 1006 874
MILWAUKEE, WI MAR 12 451 482
CHICAGO, IL MAR 12 316 321
MUSKEGON, MI MAR 12 311 290
ALPENA, MI MAR 12 929 801
DETROIT, MI MAR 12 329 366
TOLEDO, OH MAR 2 211 357
CLEVELAND, OH MAR 12 69 272
BUFFALO, NY MAR 12 426 382
NORMAL TEMPS FOR SELECTED LOCATIONS AROUND THE
GREAT LAKES FOR Thu Mar 13
LOCATION HIGH LOW
----------------------------------------------
DULUTH,MN 35 17
MARQUETTE,MI 35 18
GREENBAY,WI 41 22
MILWAUKEE,WI 43 26
CHICAGO,IL 47 29
MUSKEGON,MI 43 27
ALPENA,MI 39 19
DETROIT,MI 46 28
TOLEDO,OH 47 28
CLEVELAND,OH 47 29
BUFFALO,NY 43 26
The first half of March has been well above normal across the Great
Lakes, and as such, there has been significant ice decay during this
time period. There has already been noticeable decreases in coverage
in the northern Bays and straits, as well as the shoreline ice. Ice
has been stubborn to decay in the eastern basin of Lake Erie, and
only recently have we seen a marked decrease in the fast ice over
towards Buffalo. Satellite imagery has shown that this is really
starting to break up fairly efficiently now. There is still some
fast ice in the northern lakes, mainly on the western side of the
Straits of Mackinac and in Whitefish Bay.
That said, Whitefish Bay has enough ice that it could still create
issues, especially in northwesterly winds or southerly winds.
With the Climate Prediction Center 6-10 day, 8-14 day, and 3-4 week
outlooks all looking at above normal temperatures for the entire
Great Lakes region, the chances of any additional ice formation is
very low at this point. The southern Great Lakes are particularly
warm over the next week to ten days, and by this time of year,
increasing daylight hours and increasing sun angles also work hard
against ice formation. As a result, no significant ice formation is
expected, and overall ice decay should continue relatively unimpeded
through the second half of March.
When ice exists extensively in the rivers, flushing of the ice
normally begins the first week of March. The Straits of Mackinac and
the St. Marys River usually see their last ice in mid to late April.
This will be the last ice product issued for the 2024-2025 ice
season. Special thanks to the US National Ice Center for their
coordination this season. The next freeze-up outlook for the
upcoming 2025-2026 winter season will be issued during the first
week of November and will be issued every two weeks until ice begins
to develop on the Great Lakes.
$$
Marsalek