Area Forecast Discussion
Issued by NWS Green Bay, WI
Issued by NWS Green Bay, WI
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268 FXUS63 KGRB 242352 AFDGRB Area Forecast Discussion National Weather Service Green Bay WI 652 PM CDT Fri May 24 2024 Updated aviation portion for 00Z TAF issuance .KEY MESSAGES... - Occasional showers and thunderstorms are expected into the evening hours. Brief gusty winds and heavy downpours are expected. - Memorial Day weekend starts off dry for Saturday, but rain chances increase by Sunday afternoon and continue into Memorial Day. A soaking rain could occur during this time. - A few rivers over central and eastern Wisconsin could surpass minor flood stage early next week. && .DISCUSSION... Issued at 319 PM CDT Fri May 24 2024 Short Term...Tonight and Saturday A negatively tilted upper trough and attendant surface front will produce a broken line of thunderstorms as it moves across the area into the evening hours. Showers and thunderstorms that moved across the region earlier today and cloud cover have kept the lower atmosphere stable through mid afternoon, but increasing moisture convergence and and warm advection ahead of the front should create enough instability to get things going by 22z or 23z. Strong winds and hail are the main threats from this system. The activity will end by late evening, and cLearing skies and drier air will arrive overnight. Low temperatures should be a few degrees below normal. Saturday should be mostly sunny and a bit breezy with seasonable temperatures. There could be a stray shower in far northcentral Wisconsin. Long Term...Saturday Night Through Friday A 500mb trough will swing into the area late Saturday night into Sunday morning, then move across the western Great Lakes Sunday into Memorial Day. Beyond Memorial Day, ridging is expected across the plains which will result in the western Great Lakes being in a north/northwest flow pattern. The ridge should then shift east into the western Great Lakes by Friday of next week. Temperatures through the middle of next week will run at or slightly below normal, then would likely trend warmer than normal late next week. For Saturday night, a weak surface boundary will be lurking across the far north. Per coordination with Marquette and Duluth, will have a small chance of showers and thunderstorms across the far north for a few hours into the evening. Dry conditions will prevail overnight. The next system approaches from the south Sunday morning. By noon, there will be chances of rain across much of the area west of an Eagle River to Algoma line, with a widespread rain event expected Sunday afternoon and evening. There are some difference in the track of the low that could impact rainfall amounts and also the possibility of some stronger storms across eastern Wisconsin. Rainfall totals over an inch are possible across much of the area Sunday afternoon and Sunday night. This will cause rivers to rise again with several reaching bankfull stage and at least a few rivers could reach flood stage early next week. On Memorial Day, the northwest flow pattern will result in more convection developing during the day with a cool air aloft. Some of these storms could produce gusty winds and possibly some small hail. Confidence is not high enough to add to the Hazardous Weather Outlook. The cool cyclonic flow combined with daytime heating may trigger some more showers and perhaps a few storms on Tuesday. Dry conditions are expected Wednesday and Thursday with the next chance of rain on Friday. Frost may be possible across the north Thursday morning as the latest guidance would suggest lows in the middle to upper 30s. && .AVIATION...for 00Z TAF Issuance Issued at 642 PM CDT Fri May 24 2024 Showers and embedded thunderstorms were occurring over the eastern two-thirds of the forecast area early this evening, and a scattered line of showers was noted along a cold front in western WI. The threat of severe storms has diminished, but brief gusty winds, heavy downpours and MVFR flight conditions may accompany any storms as they impact the GRB/ATW/MTW TAF sites this evening. The precipitation will end from west to east later this evening and into the early overnight as the cold front moves through. There could be a brief period of post-frontal MVFR ceilings in NC WI, but a general clearing trend is anticipated overnight. Southeast winds will become gusty from the west after the frontal passage, then turn S-SW in the mid to late afternoon on Saturday. A brief period of LLWS is expected in far eastern WI this evening, then over the northwest half of the forecast area overnight into Saturday morning. && .GRB WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION.....RDM/Eckberg AVIATION.......Kieckbusch