717 FXUS63 KMQT 042209 AFDMQT Area Forecast Discussion National Weather Service Marquette MI 509 PM EST Tue Jan 4 2022 .SHORT TERM...(This evening through Wednesday) Issued at 427 PM EST TUE JAN 4 2022 ...Hazardous driving conditions expected on Wednesday... Overall, forecast remains on track for this upcoming system/lake- enhanced event; therefore, no changes made to the headlines for this latest forecast update. There is good consistency amongst the models in terms of not only the track of the low, which is to cut across northern Lake Michigan tomorrow, but also seeing lots of agreement on an embedded heavy snow band initially developing out across the western and central portions of Lake Superior dropping south-southeastward tomorrow morning across at least the western two-thirds of the U.P. The combination of ample atmospheric moisture, favored NErly flow off of Lake Superior, and this frontogenetical band trekking through will create the potential for 1 to 2+ inch per hour snow rates within this heavy band. In terms of timing, it looks to occur right in the heart of the morning commute, so even if the roads initially don't seem very poor, they could rapidly deteriorate within this band, especially if traveling within the higher terrain areas (of the warned counties) simultaneously. Snow will continue falling throughout the day, with everyone in the U.P. picking up at least a couple of inches before the day is done. On the Lake Michigan side, winds out of the S to SE out ahead of the low's center tonight will allow for lake-enhancement snow into portions of the eastern U.P., particularly near the Garden Peninsula, but will be relatively short-lived as the winds back with the lowpa. Speaking of lowpa, the winds will pick up as the day progresses, especially near and along Lake Superior, creating blowing snow. These winds coupled with falling temps throughout the day will also create chilly wind chills, with single digit wind chills appearing by day's end, and even sub-zero wind chills in the west. Lows tonight will be in the teens and 20s, and highs tomorrow will occur early in the day, especially across the west half, with widespread 20s expected, perhaps near 30 degrees along the lakeshores, but again, following that non-diurnal temp curve. Bottom line: don't focus on the snow amounts when it comes to anticipating impacts. The primary concerns for this forecast period revolve around the hazardous driving conditions expected, especially if finding oneself within an area of heavy snow falling. The snow will fall quickly in a short amount of time, reducing visibilities in addition to quickly accumulating on roads, and will become even more treacherous by the afternoon when blowing snow picks up. .LONG TERM...(Wednesday night through Tuesday) Issued at 448 PM EST TUE JAN 4 2022 The primary weather hazards early in the extended are below normal temperatures allowing for locally heavy lake effect and lake enhancement to persist into Friday. Warm air advection late Friday into Saturday results in a period of light snow as temps briefly warm above normal ahead of Sunday's arctic cold front. ECMWF EFI guidance is already pointing to a potentially extreme arctic blast from late Sunday into early Tuesday. Starting at 00z Thursday, lake enhanced snow will be ongoing with the heaviest snowfall expected where northeasterly upslope is maximized. Low level flow weakens and backs more northerly across western Lake Superior by Thursday evening. Winds weaken and continue to back northwesterly Thursday night with southwesterly winds spreading over the lake on Friday, effectively ending LES potential. A more detailed looks shows two distinct 500 mb lows that pivot across the region with the first low moving away at 00Z Thursday while the next one approaches. While weaker than the first, this secondary episode of synoptic scale supports ongoing LES via the seeder-feeder process. Slightly cooler air behind the second system allows inversion heights to gradually increase from ~4kft at 00Z Thursday to >5kft at 00Z Friday. Even though the increase is small, it could represent one last hurrah of snowfall before WAA kicks in Friday morning. WAA begins in earnest Friday night and frontogenesis may lead to some light snow across the CWA. WAA continues through Saturday, but a low-level inversion limits our warm-up to the 20s. The warmest locations downwind of Lake MI could approach the freezing mark. However, the warm-up will be brief as the next arctic cold front rapidly pushes southeast across our CWA late Saturday night into Sunday. Deterministic 12z guidance indicates a bubble of -33C 850 mb temperatures tracking southeast across Ontario Sunday night suggesting lake-850 mb delta-T values increasing to near or above 35C. There could be substantial LES early next week for NW wind snow belts even though the DGZ is below the ground/lake surface. Potentially extreme cold and wind chill hazards are also a distinct possibility. && .AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon) Issued at 1252 PM EST TUE JAN 4 2022 Snow is on its way, impacting all three terminals tonight into tomorrow. Currently, KCMX and KSAW are wavering between IFR and MVFR, but once the snow sets in, low-end MVFR is expected to be the max, with IFR expected to dominate, and likely that LIFR will make an appearance. Have gone with a bit more broadbrush approach to this TAF issuance, but less than 1SM is expected; just a matter of refining those details in subsequent TAF issuances. SErly winds to start will back to the NE for the latter portions of this TAF period. && .MARINE...(For the 4 PM Lake Superior forecast issuance) Issued at 501 PM EST TUE JAN 4 2022 Gales early tonight will turn into NErly storm-force gusts by the pre-dawn hours as a low pressure system traverses past. These storm-force gusts will drop back down into gales by late tomorrow, with winds continuing to back to the N-NE. Gusts will remain above 25 knots late tomorrow night into early Thursday, trending downward by day's end. Less than 25 knots is expected to end out the week, with Srly to SWrly winds exceeding 25 knots later on Saturday and remaining elevated through the weekend into early next week but from primarily out of the NW. In addition to the winds, marine interests should also be aware of the heavy freezing spray expected tonight into early Thursday. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... Winter Storm Warning from 1 AM to 7 PM EST Wednesday for MIZ004- 005-084. Winter Weather Advisory from 1 AM EST /midnight CST/ to 7 PM EST /6 PM CST/ Wednesday for MIZ006-007-010-011-014-085. Winter Storm Warning from 10 PM EST /9 PM CST/ this evening to 7 PM EST /6 PM CST/ Wednesday for MIZ001>003-009. Lakeshore Flood Advisory from 4 AM EST /3 AM CST/ Wednesday to 1 AM EST /midnight CST/ Thursday for MIZ001>003-009. Lakeshore Flood Advisory from 7 AM Wednesday to 4 AM EST Thursday for MIZ004>007. Lake Superior... Heavy Freezing Spray Warning from 4 PM Wednesday to 10 AM EST Thursday for LSZ267. Gale Warning from 7 AM to 9 PM EST Wednesday for LSZ267. Heavy Freezing Spray Warning from 1 AM Wednesday to 10 AM EST Thursday for LSZ266. Gale Warning from 3 AM to 10 PM EST Wednesday for LSZ266. Gale Warning from 5 AM to 9 PM EST Wednesday for LSZ265. Heavy Freezing Spray Warning from 10 PM this evening to 10 AM EST Thursday for LSZ263-264. Storm Warning until 1 PM EST /noon CST/ Wednesday for LSZ162-263- 264. Gale Warning from 7 AM to 7 PM EST Wednesday for LSZ249>251. Gale Warning from 5 AM to 1 PM EST Wednesday for LSZ248. Gale Warning from 1 AM EST /midnight CST/ to 9 PM EST /8 PM CST/ Wednesday for LSZ241>245. Gale Warning from 1 AM to 1 PM EST Wednesday for LSZ246-247. Gale Warning from 1 AM EST /midnight CST/ to 7 PM EST /6 PM CST/ Wednesday for LSZ240. Heavy Freezing Spray Warning from 10 PM EST /9 PM CST/ this evening to 7 AM EST /6 AM CST/ Thursday for LSZ162. Lake Michigan... None. && $$ SHORT TERM...lg LONG TERM...EK AVIATION...lg MARINE...lg