860 FXUS63 KGRB 260958 AFDGRB Area Forecast Discussion National Weather Service Green Bay WI 358 AM CST Tue Dec 26 2023 Forecast discussion for routine morning forecast issuance .KEY MESSAGES... - Widespread rain tonight into Tuesday morning with most locations receiving 0.20-0.70". No hydro concerns expected. - Record or near record temps continue into Tuesday. Temps are expected to trend cooler through the end of this week and into the weekend, but will remain about 5-10 degrees warmer then normal for late December. && .DISCUSSION... Issued at 358 AM CST Tue Dec 26 2023 Short Term...Today...Tonight...and Wednesday An upper low over the Central Plains will remain nearly stationary today, and then drift slowly to the southeast Wednesday. The left exit region of a 100+ knot jet at 300mb will produce upward vertical motion across Wisconsin as it rotates around the upper low, assisting in the formation of an area of rain that will move north across the area this morning. The rain could continue in the far north into the early afternoon. Cold advection will make for high temperatures early in the day, with steady or falling temperatures in the afternoon. There could be one or two record high temperatures this morning before the cooler air arrives, but nothing like the record highs established Christmas Day. Cloudy skies and a lack of snow cover will keep low temperatures about ten degrees higher than usual tonight, though it will be colder than the last few nights. Some clearing is expected Wednesday as some drier air rotates around the upper low. It will continue to be much milder than usual, with high temperatures around ten degrees above normal for this time of the year. Long Term...Wednesday Night Through Monday Wednesday night through Thursday...The slow moving upper low will pass south of the region during this time period, bringing one last chance for a few scattered showers. Forcing during this time will be weak, relying mainly on easterly flow over Lake Michigan and weak warm air advection around the upper low. Still, with a fairly saturated sounding, drizzle is not out of the question Wednesday night into Thursday morning. Any accumulations will be minor, but with temperatures finally dipping below freezing again early Thursday, there is some potential for some light icing impacts on raised surfaces like bridges. Most roads will likely prove too warm after the past few warmer days to accumulate any icing however. Rest of the forecast...Drier conditions follow for Friday and Saturday before the next broader shortwave dips southwards into the Great Lakes region. There is considerable divergence on the western extent of precipitation associated with this shortwave, but some light precipitation could graze the area, likely in the form of snow. Although no major airmass exchanges are in the extended, temperatures will gradually moderate closer to normal over the next week, getting to around 5 to 10 above normal next weekend (as opposed to the record breaking 25+ above normal from the past couple of days). && .AVIATION...for 06Z TAF Issuance Issued at 1042 PM CST Mon Dec 25 2023 An occluded front will sweep from southwest to northeast across the region late tonight into Tuesday morning. An arcing band of rain will accompany the front. Flight conditions will deteriorate to IFR and LIFR again through the overnight with the approaching front. Timing of the lower flight conditions has been delayed by a couple hours. After the rain ends with the passage of the front, improving conditions to MVFR are expected Tuesday afternoon. Finally, low- end LLWS over central and east- central Wisconsin with winds at 2000 ft will around 35-40 kts will diminish by around 10z. && .GRB WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION.....RDM/Uhlmann AVIATION.......MPC