FZUS81 KCLE 191839 ICEGL GREAT LAKES FREEZE-UP OUTLOOK NATIONAL WEATHER SERVICE CLEVELAND OH 139 PM EST Tue Nov 19 2024 ...Great Lakes Ice Season for 2024-2025 Expected to Be Below Average Ice Cover... In a summary preface for this 2nd outlook, expect a cool down overall more towards normal temperatures in the next two weeks, and perhaps even a bit below normal heading into the end of November/early December time frame with some freezing temperatures north. Great Lakes water temperatures overall continue to run significantly above normal. As we head through the last half of November and into the first part of December, forecast future weather patterns for the Great Lakes region are exhibiting a colder trend compared to what we have seen, but for this area, that essentially equates to more typical weather for this time of year. Over the next two weeks, expecting an active pattern with multiple low pressure systems moving through, the first of which will occur the middle to the end of this week. An expansive upper level low pressure system not only brings in colder air along with some rain/snow potential, but significant wind for all of the lakes that will allow for more efficient heat removal, which has been decidedly slow so far this season. Other weather systems moving through may only affect certain portions of the Great Lakes, so variability in the weather for each particular lake should be expected beyond this weekend. A brief warm up is expected early next week in the southern Great Lakes. Long range model ensembles are showing Arctic air settling southward into the northern Great Lakes beyond the middle of next week where we could see our first period where temperatures do not climb above freezing during the day for our far northern locations. But the trend overall is for more normal to slightly below normal temperatures for this time of year, which will feel quite different given the above normal temperatures experienced in October and the first half of November. We remain in neutral El Nino conditions, although it is still expected to creep into La Nina territory for the winter months, and a weaker La Nina is expected. Meanwhile, the North American Oscillation (NAO) is currently in a negative phase and should remain slightly negative into early December. For the Great Lakes, this more directly translates to a lack of sustained milder conditions that we have seen recently, which meshes with the long range model ensembles. While it is going too far to say that it will be cold, more normal to slightly below normal temperatures for the region, on the whole with some natural variability, should prevail. Taking a broad look at the Great Lakes, average lake-wide surface water temperatures are 3-6 degrees Fahrenheit above normal for mid November with Lake Erie and Lake Michigan on the higher end of that range. Comparing this with averages taken from a database that goes back to 1995, Lake Erie and Lake Huron are currently the warmest they have been on the whole since this period of record began. Lake Superior and Lake Michigan are in the top 3 as it currently stands, but again, this is a fairly limited database. We will be watching the system this weekend closely in reference to the expected windy conditions across the lakes and how much those surface water temperatures come down heading through next week. Current surface water temperatures across the Great Lakes have Lake Superior running the 40s with the coolest waters in the western end. For Lake Michigan, the northern half is in the lower to mid 50s, while the southern half has pockets of upper 40s appearing, but still dominant in the lower to mid 50s as well. Lake Huron currently sees temperatures in the upper 40s north to the lower to mid 50s south, and for Lake Erie, low to mid 50s lake-wide. Whitefish Bay is around 50F, St Mary's River is currently in the lower to mid 40s, and Lake St. Clair is also around 50F. No significantly colder water is present in any of the areas that typically respond quicker, including Duluth Harbor, Green Bay, Big/Little Bay de Noc, the Straits of Mackinac, Saginaw Bay, or the western third of Lake Erie. But that may change as we get into early December. For this issuance, no significant ice formation is expected in the next two weeks. Skim ice could be possible towards the end of this two week period in nearshore, shallower areas of the far northern Great Lakes region after a cold overnight if there is enough sustained sub-freezing temperatures leading up to it to get the surface water temperatures down to the mid 30s. Ice formation is determined by two factors: The amount of heat stored in the water from the summer and how fast that heat can be removed by arctic outbreaks of Polar air and high winds. Long range outlooks do not consider the "storminess" factor which can significantly alter the thermal structure of the lake over short periods of time. FREEZING DEGREE DAY ACCUMULATIONS AT SELECTED STATIONS COMPARED TO NORMAL CALCULATED ON Tue Nov 19: LOCATION DATE NORMAL CURRENT ---------------------------------------- DULUTH, MN NOV 17 10 0 MARQUETTE, MI NOV 17 6 0 SAU_S_MAR, MI NOV 17 0 0 GREENBAY, WI NOV 17 0 0 MILWAUKEE, WI NOV 17 0 0 CHICAGO, IL NOV 17 0 0 MUSKEGON, MI NOV 17 0 0 ALPENA, MI NOV 17 0 0 DETROIT, MI NOV 17 0 0 TOLEDO, OH NOV 17 0 0 CLEVELAND, OH NOV 17 0 0 BUFFALO, NY NOV 17 0 0 THE NEXT FREEZE-UP OUTLOOK WILL BE ISSUED IN APPROXIMATELY TWO WEEKS. $$ Marsalek