


Area Forecast Discussion
Issued by NWS Green Bay, WI
Issued by NWS Green Bay, WI
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652 FXUS63 KGRB 302047 AFDGRB Area Forecast Discussion National Weather Service Green Bay WI 347 PM CDT Mon Jun 30 2025 Forecast discussion for routine afternoon forecast issuance .KEY MESSAGES... - Scattered thunderstorms will come to an end this evening. Stronger storms could produce gusty winds and small hail. Isolated severe storms with gusts to 60 mph and large hail to one inch are possible. - Temperatures will be above normal through the week. - Rain and thunderstorms are possible throughout Friday and Saturday which may impact 4th of July celebrations. && .DISCUSSION... Issued at 346 PM CDT Mon Jun 30 2025 Short Term...Tonight and Tuesday Scattered thunderstorms moved across portions of far northeast Wisconsin this afternoon. This cluster of thunderstorms sent an outflow boundary southward to near Green Bay. Scattered thunderstorms were also noted across west-central and northwest Wisconsin. Meanwhile, lower dewpoints were filtering into eastern Wisconsin on westerly winds and deeper mixing. For the rest of the afternoon into this evening, cyclonic flow aloft and daytime heating triggered the scattered storms across the western part of the state. Some of these storms are expected to make it into north-central and central Wisconsin during the late afternoon and evening. Most of the stronger storms will be capable of producing wind gusts to 45 mph and small hail. Could not rule out an isolated storm with wind gusts to 60 mph and large hail to one inch in diameter. The storms should come to an end later this evening as we lose the heating of the day. Later tonight when winds diminish and skies become mostly clear, patchy fog is expected to develop. Lows should drop into the middle 50s to lower 60s. On Tuesday, some fair weather cumulus will develop during the late morning and continue through the afternoon. Highs should top out in the upper 70s to middle 80s. Long Term...Tuesday Night Through Monday Expecting generally quiet weather from Tuesday night through Thursday night with high pressure at the surface and rising upper heights. There are some subtle features, including a upper jet streak and weak surface cold front which could bring small precip chances therefore maintained 15-30% PoPs at times, otherwise dry. A few thunderstorms are possible, too, but severe weather potential is low. Still watching the potential for rain and thunderstorms Friday through Saturday night. A number of factors at play, including the timing of various features which make narrowing down the specifics this far out challenging. Overall dynamics are modest, but an approaching surface boundary and low-level WAA will be enough to initiate at least some thunderstorms. Forecast instability Friday afternoon gets as high as ~2000 J/kg, but deep shear is weaker, ranging from 15-30 kts. Instability Friday night and Saturday is lower and generally less than 1000 J/kg, aside from the southeast wedge of the forecast area, which builds up to 1500 J/kg Saturday afternoon. Timing and strength of thunderstorms will come down to the timing of these features, which is trending more towards late Friday night or Saturday at the moment. Continued with NBM PoPs which generally show a consistent wet period, but it will be a mix of scattered rain/storms and no-precip. Temperatures will remain above normal through the week with highs in the 80s, and nearing 90 degrees on Friday. Humidity will also remain noticeable due to dew points in the 60s most days, and even some low 70s in the mix Friday into Saturday. && .AVIATION...for 18Z TAF Issuance Issued at 1244 PM CDT Mon Jun 30 2025 Scattered thunderstorms will impact north-central and northeast Wisconsin this afternoon into this evening. Some of the stronger storms could produce wind gusts to 35 knots and small hail. Confidence is low in the exact timing across eastern Wisconsin as temperatures in this region have reached the convective temperatures and outflow boundaries are sinking south. The main feature that will trigger additional thunderstorms will be across northern Wisconsin this afternoon. The storms should diminish and then end after sunset. For this afternoon, areas of MVFR CIGS will rise into the VFR category outside thunderstorm activity. Later tonight, some patchy fog is expected to form as skies clear and winds diminish. Cumulus field between 2,500 and 3,500 expected to redevelop late Tuesday morning. && .GRB WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION.....Eckberg/KLJ AVIATION.......Eckberg