


Area Forecast Discussion
Issued by NWS Green Bay, WI
Issued by NWS Green Bay, WI
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436 FXUS63 KGRB 032340 AFDGRB Area Forecast Discussion National Weather Service Green Bay WI 640 PM CDT Thu Jul 3 2025 Updated aviation portion for 00Z TAF issuance .KEY MESSAGES... - Continued potential for showers and thunderstorms late tonight into Friday (July 4th). Marginal chance for severe weather tonight. - Better chance for widespread rain and storms will occur Saturday and Saturday night. There is marginal chance for severe and the potential for heavy rainfall Saturday into Saturday night. - Temperatures will be above normal through the holiday weekend, with very warm and humid conditions expected Friday (July 4th) and Saturday. && .DISCUSSION... Issued at 149 PM CDT Thu Jul 3 2025 Rain late tonight into Friday... The weak frontal zone remains visible on satellite this afternoon as an area of cumulus stretching from southwest Wisconsin to the western portions of the state. As warm air advection kicks up again late this afternoon and evening, this boundary will once again lift into the region for the early overnight period. Elevated showers and thunderstorms are then expected to develop again, pushing into central Wisconsin from the southwest. Best timing still remains from the overnight period around midnight through the mid to late morning hours on Friday. Would expect the best convective potential to be earlier in the overnight period, with just some weaker storms or even just showers around by the early morning period. Severe weather potential remains fairly marginal, with relatively little instability and shear in the region, but some brief wind gusts and small hail will be possible. Any remaining convection will then slowly be suppressed through the afternoon on Friday as ridging works its way into the region. Maintained low pops further east as the ridging arrives, as some meso models do allow for weak instability late in the day. Regardless, mostly dry conditions are expected by firework time in the early overnight. Saturday... The best chance for widespread rain and showers arrives on Saturday as a cold front sweeps across the region from west to east. Models have largely kept the slower arrival time, bringing the front through mainly in the afternoon to evening period of Saturday. As a result, 1-2 thousand J/kg CAPE will have a chance to develop ahead of the front before storms arrive. Shear still looks weaker but sufficient, around 20-30 knots, so some stronger or a few severe storms will remain in the forecast. SPC currently has most of northeast Wisconsin in the Marginal risk category for severe weather, which makes sense. In addition to any severe weather, ample moisture in the region will support a heavy rain threat, with many areas seeing at least 40-60% of exceeding half an inch of rain with the storms. Rest of the Forecast... Drier conditions then return behind the cold front Saturday, as high pressure returns through early next week. The next hints of some unsettled weather are not in the forecast until we get towards the middle of next week. Temperatures... Above normal temperatures are expected through Saturday, followed by near to a little below normal conditions through the middle of next week. Very warm and muggy conditions arrive for Friday (July 4th) and linger over eastern WI into Saturday, with heat indices into the lower to middle 90s. The heat and humidity will impact outdoor activities for the 4th of July, but heat indices fall a little short of advisory criteria at this point. && .AVIATION...for 00Z TAF Issuance Issued at 631 PM CDT Thu Jul 3 2025 Isolated thunderstorms extended from just east of Wisconsin Rapids to near Wautoma to Red Granite early this evening. This cluster of storms could produce wind gusts to 35 knots and small hail at KY50 until 02z. Otherwise, additional thunderstorms are expected to develop alter this evening and overnight. These storms are expected to develop around or a few hours after 06z at KAUW/KCWA. Highest confidence in storms are across central WI as models differ on timing and eastward extent of the storms into the morning of 4th of July. For the other TAF sites, went with a PROB30 group due to the uncertainty in the amount of storms during this time frame. Hot and increasingly humid conditions expected for the 4th of July. Along with the heat and humidity, hazy condiitons may develop at times. && .GRB WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION.....Uhlmann AVIATION.......Eckberg