FXUS63 KGRB 061118 AFDGRB Area Forecast Discussion National Weather Service Green Bay WI 518 AM CST Mon Feb 6 2023 Updated aviation portion for 12Z TAF issuance .SHORT TERM...Today...Tonight...and Tuesday Issued at 329 AM CST Mon Feb 6 2023 Early this morning - High pressure is stretching north to south across the central Great Lakes, while the next upper trough and weak surface cold front is moving east across the western Plains. - The back edge of the low stratus deck extends from Rhinelander to just north of Green Bay at 3 am. Where skies cleared, temperatures tanked like at Tomahawk and Wautoma where readings at 3 am are 2 above and 5 above respectively. Temps are in the middle teens to low 20s where overcast conditions exists. - The back edge of the stratus should continue to slowly move northeast through the rest of the early morning hours. Rapids falls in temps are likely where skies transition from overcast to clear. - Middle and high clouds are already spreading east into the northern Mississippi Valley ahead of low pressure over the Dakotas. Forecast concerns: Light snow and freezing rain accumulations as the storm system over Plains moves across the region tonight. Today - Synopsis: Shortwave trough and surface cold front will continue to march east and into the northern Mississippi Valley this afternoon. - Cloud Cover/Precip: The morning stratus deck will continue to slowly move northeast and finally exit later this morning. Meanwhile, mid and high clouds will gradually spread east and thicken over the course of the day. Light precip via increasing moisture transport and isentropic ascent aloft will be approaching north-central WI by 6 pm. - Temperatures: Increasing southeast to south winds will push highs into the low to mid 30s today. This is slightly cooler than the forecast highs from the National Blend. - Hazards: None expected. Tonight and Tuesday - Synopsis: Strong ascent will accompany the shortwave trough and cold front as it moves across the area tonight and exits on Tuesday morning. A 50-60 kt low level jet will transport precipitable water values approaching 2.5 standard deviations above normal into the area in the evening. - Cloud Cover/Precip: A band of precipitation will rapidly sweep across the area from west to east this evening before exiting to the northeast overnight. Forecast reflectivity indicates convective looking returns supported by mid-level lapse rates upwards of 7 C/km. Surface temps continue to indicate that a band of freezing rain is possible with the highest probability stretching from Wausau to Keshena to Wausaukee. Up to 0.05 inches of freezing rain is possible. Snow is more probable north of this freezing rain band while rain will be more probable south of the band. 1-2 inches of snow is possible over the northwoods before the precip exits. A few hours of drizzle or freezing drizzle is also possible within the dry slot and behind the band of precipitation. Most precip will have ended by 6 am Tue except for possibly the northern Door and Vilas counties. Then skies will gradually clear from late morning through the afternoon on Tue. - Temperatures: Will gradually rise tonight with strong southerly flow present. Lows will likely occur in the evening. Then temps will be relatively steady on Tue. - Hazards/Impacts: Widespread slippery and/or icy roads will be possible tonight north and west of the Fox Valley from ice and snow accumulations. Considered issuing a winter weather advisory but will handle with an SPS and pass along concerns to the next shift. Will issue a Gale Warning on Lake Michigan due to south winds up to 40 kts, peaking at midnight. .LONG TERM...Tuesday Night Through Sunday Issued at 329 AM CST Mon Feb 6 2023 The split flow pattern at 500mb will allow for a milder Pacific air mass to remain in place through the weekend. Temperatures will run well above normal during through much of the work week. Temperatures are likely to trend closer to normal next weekend. The main concern for this period will be the system moving across the middle portion of the country Wednesday into Friday. There has been little consistency among the different models. There has been considerable differences from run to run on the various models as well. For tonight, the GFS/ECMWF have trended northward with precipitation making it into our southern counties late Wednesday night. The NAM was the quickest solution while the Canadian pretty much misses the forecast area. Have trended toward the GFS/ECMWF with respect to timing/location of the heaviest precipitation late Wednesday night and Thursday. The other concern will be the precipitation type as models are showing warm air aloft at the onset of the precipitation. If the stronger ECMWF is correct, the light precipitation will switch over to all snow Wednesday night into Thursday morning as the axis of heavier precipitation moves across the forecast area. The ECMWF is indicating a swath of heavier snow across portions of the area. The GFS model is also indicating 4 to 6 inches of snow on the latest numerical guidance at Green Bay. Due to the uncertainties in the models, confidence is low on the details of the system and how much snow would fall across the area. Also, temperatures will be near freezing Wednesday night and should rise above freezing on Thursday which would make it a heavier snow and that would compact and melt during the day Thursday. A weak feature will move across the area Thursday night and Friday bringing a continued chance of precipitation. Dry conditions are expected next weekend. As the high slides east of the state, the pressure gradient tightens, southerly winds will be on the increase Sunday bringing milder air into the region next Sunday and Monday. && .AVIATION...for 12Z TAF Issuance Issued at 517 AM CST Mon Feb 6 2023 - IFR/MVFR ceilings will continue to slowly move northeast across far north-central and northeast Wisconsin this morning. Think by late morning these clouds will have exited northeast WI. - Mid-level clouds and southeast winds will gradually increase through the daylight hours ahead of the next storm system. Strong winds aloft will bring low level wind shear to the region from late afternoon through early evening. - A potent storm system will bring a wintry mix to the region tonight. Light snow and icing are possible north and west of the Fox Valley, particularly during the evening. - In the wintry mix of precip, IFR/LIFR ceilings and visibilities are likely tonight. Some improvement in both areas are possible late tonight into Tuesday morning as the precip ends. && .GRB WATCHES/WARNINGS/ADVISORIES... None. && $$ SHORT TERM.....MPC LONG TERM......Eckberg AVIATION.......MPC