FXUS63 KGRB 040525 AFDGRB Area Forecast Discussion National Weather Service Green Bay WI 1125 PM CST Tue Dec 3 2024 Updated aviation portion for 06Z TAF issuance .KEY MESSAGES... - Periods of light snow/snow showers expected through Wednesday night with the highest risk of accumulations (50-90% chance of at least 2") across far northern Wisconsin. Brief visibility reductions will be possible in snow showers region-wide on Wednesday. - Gusty west to northwest winds developing Wednesday into Wednesday evening (30 to 60% chance for gusts of at least 40 mph) with colder air resulting in wind chills as low as 5 below to 10 below zero by Thursday morning. - Temperatures will gradually warm heading into the weekend with occasional light snow/flurry chances, but any impacts look low at this time late this week and this weekend. && .DISCUSSION... Issued at 247 PM CST Tue Dec 3 2024 Tonight-Thursday: Turning colder, windy with areas of snow showers Upstream surface obs and radar imagery shows an area of light snow working across northern Minnesota and northwest Wisconsin this afternoon, although dry low-level air will take some time to saturate. This area of snow will translate east this evening with the strongest synoptic lift/warm advection skirting by mainly across far northern WI into the Upper Peninsula of Michigan. Overall, amounts should be light with up to around an inch possible along the WI/MI border. On Wednesday, a strong mid-level trough will drive southeast across the Great Lakes with a surge of strong low-level cold advection. With steepening low-level lapse rates beneath the trough, expect scattered snow showers to develop. Accumulations overall look minimal with these, but brief visibility reductions could occur and possibly result in a few slick spots. In addition, the cold advection/steep lapse rates, combined with around 40 kts winds at the top of the mixed layer will lead to strong, gusty northwest winds. Chances for at least 40 mph winds from the 03.12Z HREF are around 30 to 60 percent during the later afternoon/night on Wednesday. The strong push of cold air will result in falling temps Wednesday afternoon. The gusty northwest winds and temps in the single digits and teens will likely result in wind chills around 10 below zero in spots on Thursday morning, so those heading outdoors Wednesday night and Thursday will want to prepare for cold weather. Some lake contribution to the snow will likely occur across north- central WI Wednesday afternoon into Thursday, especially as winds shift more northwesterly and the mixed layer deepens. Several inches of snow are possible across Vilas County. Have coordinated with WFOs Duluth/Marquette to hoist a Winter Weather Advisory for Vilas County Wednesday/Wednesday evening. Overall, chances for at least 2" of snow are confined mainly to north-central Wisconsin and Door County, but highest across Vilas County. Friday-Tuesday: Warming into the weekend, higher precip potential early next week. Heading through late week into early next week, northwest flow aloft will relax with the mid-level flow shifting southwesterly by Monday/Tuesday. After continued chilly conditions through Friday as the Canadian surface high passes south and east, warmer air will spread back across the area over the weekend, including highs possibly eclipsing 40 degrees by Sunday. Overall, weather impacts look low through the weekend with global ensembles (GEFS/EPS/CMC) showing only low probabilities (10-30%) at times for light snow/flurries associated with any weak waves in northwest flow. Confidence in pattern evolution lowers early next week with a broad trough forecast to evolve across the Rockies. There is considerable spread in how this trough and smaller scale troughs progress during this time, but an precipitation chances trend upward (30-50%) by Monday of next week. && .AVIATION...for 06Z TAF Issuance Issued at 1125 PM CST Tue Dec 3 2024 Conditions varied between MVFR/IFR across northern Wisconsin in snow showers, with MVFR/VFR conditions across central and east-central Wisconsin with light snow at times. This area of snow across the north will move out of the region during the overnight hours, leaving MVFR conditions in place. Further south conditions will continue to bounce between MVFR/VFR. Gusty southwest winds will continue during the overnight hours. A cold front will turn winds from west to northwest on Wednesday morning. Scattered snow showers will also track through the region with the cold front, reducing CIGs to MVFR. && .GRB WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory from 9 AM Wednesday to 6 AM CST Thursday for WIZ005. && $$ DISCUSSION.....JM AVIATION.......Kurimski