Expires:No;;005227 FXUS63 KMQT 162124 AFDMQT Area Forecast Discussion National Weather Service Marquette MI 424 PM EST Sun Feb 16 2025 .KEY MESSAGES... - Northwest flow lake effect snow continues for the next few days, heaviest tonight through Monday night. Over western Upper MI, Ontonagon County will be favored for most persistent heavier snow, up to around 1 foot tonight through Monday night. Over the east, Alger, northern Schoolcraft and Luce counties will be favored for heavier snow. Snow accumulations of 10 to 20 inches tonight through Monday night, greatest between Grand Marais and Seney. - Gusty northwest winds will create areas of blowing and drifting snow. Brief whiteouts expected in Alger County, particularly along M-28 where the road is exposed to winds off of Lake Superior. - Cold conditions for the next few days. Low temperatures mostly zero to around 10 below tonight through Tuesday night. Wind chills 15 below to 25 below interior western Upper Michigan Monday morning and Tuesday morning. && .SHORT TERM /THROUGH TONIGHT/... Issued at 243 PM EST Sun Feb 16 2025 Upper air pattern consists of a 500 mb closed low near Lake Winnipeg and a trough over the upper Great Lakes. The closed low heads slowly southeast into western Ontario by 12z Mon just north of International Falls. Lake effect snow will continue for this forecast period with winds becoming northwest. Northwest wind affected lake effect snowbelts will come into play this forecast period where the heaviest snow will be. Couple of things to be concerned about for this forecast. First is the lake effect snow will continue overnight. With northwest winds occurring, strong directional convergence sets up which will cause some strong lake effect snow bands to move across Ontonagon, Alger and Northern Schoolcraft counties and the winter storm warning looks good still. Advisory areas look good as well where they are. Second issue is possible apparent air temperature values. With northwest winds, this will tend to cause lake effect clouds to continue to move inland. The wind does not look to decouple tonight, so ideal radiational cooling does not set up. Think cloud cover will be persistent enough over the west combined with the wind which will keep apparent temperatures above -25F, so no cold advisory will be needed. A few places will get close though. && .LONG TERM /MONDAY THROUGH SUNDAY/... Issued at 423 PM EST Sun Feb 16 2025 Significant positive height anomalies have recently dominated the Arctic, dislodging Arctic air southward as negative height anomalies tend to dominate to the s toward the mid-latitudes in this type of situation. That includes Canada where an expansive Arctic air mass still currently resides. Widespread -20s and -30s F were observed early this morning across the Prairie Provinces into northern Ontario. A -51F was even noted in northern Saskatchewan. This Arctic air is spilling across the International Border into the Northern Plains and Upper Mississippi Valley. The Arctic positive height anomalies are currently breaking down and are on the move. One piece will drop s to Hudson Bay, forcing negative height anomalies/troffing s into the Great Lakes thru Tue. This will support the moderating core of Arctic air pushing thru the Upper Mississippi Valley into the Great Lakes region. So, for Upper MI, blo normal temps will prevail thru Wed with the coldest day likely on Mon. Thereafter, a trend toward positive height anomalies expanding all along the vcnty of the International Border will lead to a warming trend during the last half of the week, bringing temps back to around normal or a little above normal by the weekend. As for pcpn, the evolving pattern will not be favorable for any system snows this week. The lack of system snows for Upper MI has been a theme of this winter, just like it was last winter. The Arctic air, however, will support LES through about Thu morning. Beginning Mon, fcst soundings show inversion heights around 7-8kft as mid-level low currently over southern Manitoba shifts over Lake Superior while opening up. Combined with 850mb temps ranging from around -23C over eastern Lake Superior to around -28C over western Lake Superior, expect vigorous LES under northwesterly low-level flow. Models over the last 24hrs have been very consistent in showing strong low-level convergence off of western Lake Superior into Ontonagon County tonight lingering thru Mon morning before weakening, but still remaining thru the aftn. To the e, another area of strong low-level convergence persists thru the day and holds nearly steady across eastern Alger County, ne Schoolcraft County and western Luce County. In both of these areas, expect hvy LES, but it will be most persistent thru the entire day in the latter area. In Ontonagon County, another 2-5 to locally 6 inches of snow is likely on Mon. In eastern Alger, ne Schoolcraft and western Luce, 8-12 inches of new snow is easily achievable during the day Mon. If the convergence becomes highly focused and stationary, accumulations on Mon could reach 12-16 inches in a small localized area. Across the rest of the eastern fcst area affected by nw flow LES, expect 2-5 inches of snow in general. Over western Upper MI, expect 1-3 inches of snow outside of Ontonagon County. With the opening up mid-level low arriving, expect some diurnal component -shsn, resulting in -shsn/flurries extending well inland in the aftn. With temps of -5 to -10F in the morning across the interior w and winds 5-10mph, wind chills will be -18 to -25 range, not quite to cold weather advy criteria of widespread -25 or lower. Afternoon high temps will range from the lower single digits above 0F interior w to around 10F above s central and e. Inversions gradually begin to fall during Mon night as troffing weakens/heights rise over the area. So, snowfall rates will also begin to ease. The low-level convergence zone into Ontonagon County remains nearly stationary during Mon night. To the e, the low-level convergence zone into eastern Alger/northern Schoolcraft/Luce counties also remains near stationary. As a result, those areas will continue to see the heavier, most persistent shsn, about 2-4 inches of new snow w and 4-7 e. Outside of those favored convergence zones, the ongoing nw flow LES will leave another 1-3 inches of new snow during Mon night. Temps by early Tue morning will be down near -10F in the interior w with wind chills again down in the -18 to -25 range. Inversions settle in the 4-6kft range for Tue/Wed, lowest w, leading to lighter nw flow LES. Expect 1-3 to locally 4 inch accumulations per 12hrs with the higher accumulations over the e. Winds temporarily veer a little more northerly Tue night and then again Wed night into Thu morning, so the LES may shift to cover more of northern Upper MI during those times. WAA from the n will then raise 850mb temps toward -10C on Thu, so LES will wind down and likely end. Dry weather expected for at least Fri with broad sfc high pres ridging moving across the Mississippi River Valley. WAA regime and uncertain timing of shortwaves in wnw flow will probably lead to a little -sn at some point over the weekend. Temps Fri thru the weekend will be around normal to a little above normal for mid to late Feb. && .AVIATION /18Z TAFS THROUGH 18Z MONDAY/... Issued at 1132 AM EST Sun Feb 16 2025 Northwesterly lake effect snow will continue for this forecast period. Conditions will stay MVFR for the most part at IWD with periods of IFR in the lake effect snow showers. CMX will remain IFR through the period with lake effect and at times will be LIFR. SAW will be IFR this afternoon and improve to VFR tonight as winds back more northwesterly and push the lake effect northeast out of the area. && .MARINE... Issued at 423 PM EST Sun Feb 16 2025 NW winds of 20-30kt will generally be the rule across much of Lake Superior thru Tue, strongest across the e half. Some gale force gusts will occur into Mon in the area generally between Grand Marais, Stannard Rock and Munising. The gale gust potential expands over more the east half of the lake during Mon night as probability of peak gusts to 35kt increases to 50-70pct. With the brisk winds and the cold airmass in place, expect periods of heavy freezing spray thru Tue. NW to N winds drop back to mostly below 20kt for Wed and Thu. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... Winter Weather Advisory until 7 AM EST /6 AM CST/ Monday for MIZ001-003-009-084. Winter Storm Warning until 7 PM EST Monday for MIZ002. Winter Storm Warning until 1 AM EST Tuesday for MIZ006-007-085. Lake Superior... Heavy Freezing Spray Warning until 7 AM EST /6 AM CST/ Tuesday for LSZ240>251-263>267. Gale Warning until 10 PM EST this evening for LSZ249. Lake Michigan... None. && $$ SHORT TERM...07 LONG TERM...Rolfson AVIATION...07 MARINE...Rolfson