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