Area Forecast Discussion
Issued by NWS Green Bay, WI
Issued by NWS Green Bay, WI
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632 FXUS63 KGRB 012346 AFDGRB Area Forecast Discussion National Weather Service Green Bay WI 646 PM CDT Sat Jun 1 2024 Updated aviation portion for 00Z TAF issuance .KEY MESSAGES... - Scattered showers/isolated thunderstorms into early this evening. No severe storms anticipated. - Areas/patchy fog expected to develop late this evening through daybreak Sunday. Some of this fog may become locally dense, mainly across central and north-central Wisconsin. - Rain and storms are possible Monday afternoon. While storms are not expected to be severe, an isolated strong gust up to 35 to 40 mph with any storms is still possible. - A better chance for strong storms arrives later in the day Tuesday. These storms may also be accompanied by heavy rainfall. && .DISCUSSION... Issued at 215 PM CDT Sat Jun 1 2024 Short Term...Tonight and Sunday Main forecast concerns to be on precipitation trends through this evening, potential for locally dense fog later tonight and how warm to take temperatures on Sunday. The 19Z MSAS surface analysis showed a weak cold front that extended from northeast MN south through far western WI into east-central IA. High pressure was situated over the Dakotas. Latest radar imagery indicated a band of light showers over eastern WI and scattered showers over central WI. Temperatures were being held in check by thick cloud cover and precipitation with readings in the 60s. The chance of showers/few thunderstorms will carry over into the evening over parts of the forecast area as the weakening cold front slides across the region and a mid-level shortwave trough lifts northeast into the Great Lakes. While the precipitation diminishes/ends later this evening, lingering low-level moisture coupled with light/variable winds are expected to generate fog overnight. This fog may become locally dense, especially over central WI where heavier rains fell earlier in the week. This fog may extend into the Bay and Lake MI as well, especially the lake where the higher dew points are moving over cooler lake waters. Min temperatures to be in the upper 40s to around 50 degrees north, lower to middle 50s south. The weak area of high pressure over the Dakotas will move into the Great Lakes on Sunday, thus once any fog dissipates, look for mostly sunny skies to prevail. Max temperatures to range from around 70 degrees near Lake MI, middle 70s to around 80 degrees inland. Long Term...Sunday Night Through Saturday An active weather pattern will continue for the first part of the work week, with chances for light rain at times late into the week into next weekend. A low pressure system developing across the Plains will bring the first chance for rain late Sunday night through Monday night as it tracks through the western Great Lakes region. Despite decent dynamics, instability with this system is not all that impressive, with MUCAPEs of 300 to 800 J/kg. The muted instability is due to the cloud cover that is expected to move into the region late Sunday night and continue through Monday night, which will prevent instability from getting out of hand. Therefore, severe weather is not expected from this first round of showers and thunderstorms. Behind this departing system Monday night, another system will be hot on its heels as another system developing over the Plains tracks through the western Great Lakes Tuesday and Tuesday night. Instability will be a lot higher with this second system, as MUCAPEs rise to 1000 to 2000 J/kg; however, bulk shear will only be around 20 knots. There could be some strong storms Tuesday afternoon and evening given the high instability, but severe weather is not expected given the relatively meager shear; however, this period in the forecast will bear watching for changes in these parameters. The low associated with this system will cut off and spin over southern Manitoba during the middle part of the week then move slowly east through the northern Great Lakes region through early next weekend. As this low meanders through the Great Lakes, several additional rounds of light rain are expected at times to end the work week and into next weekend. This low will also bring an end to the above normal temperatures experienced earlier in the week, as temperatures fall below or around normal for the late part of the week into next weekend. && .AVIATION...for 00Z TAF Issuance Issued at 645 PM CDT Sat Jun 1 2024 Any light showers are expected to come to an end early this evening. However, lingering low-level moisture, light winds, and partial clearing will create favorable conditions for fog development this evening and overnight. Visibilities are expected to drop to at least MVFR at most TAF sites, with some IFR and potentially LIFR visbys possible at CWA and AUW where clearing skies are expected. IFR visbys may also be possible at MTW given assistance from low-level lake moisture. A brief period of LIFR visbys may occur, although confidence was too low to include in the TAF. After fog burns away Sunday morning, expect VFR conditions at all sites as weak high pressure moves across the region. Some scattered daytime cumulus may develop during peak heating early Sunday afternoon and linger through the evening, although cigs are expected to remain VFR. && .GRB WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION.....Kurimski/Kallas AVIATION.......Goodin