


Area Forecast Discussion
Issued by NWS Green Bay, WI
Issued by NWS Green Bay, WI
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893 FXUS63 KGRB 271710 AFDGRB Area Forecast Discussion National Weather Service Green Bay WI 1210 PM CDT Fri Jun 27 2025 .KEY MESSAGES... - Near/below temperatures continue today, then increasing heat and humidity into the weekend, with highs in the 80s to near 90 on Sunday. - There is a chance of strong to severe storms late this weekend, especially Sunday afternoon and evening. Heavy rain and localized flooding is also possible. && .DISCUSSION... Issued at 412 AM CDT Fri Jun 27 2025 Today: Surface low pressure, cold front and mid-level shortwave will slowly exit the area this morning, with lingering light showers ending from southwest to northeast. A stray thunderstorm will remain possible as some elevated instability will reside ahead of the front. Recent rain and lighter winds will allow fog, locally dense (especially across central WI), to continue in spots this morning as well. Cyclonic flow will keep clouds around most/all of the day, with west/northwest wind gusting to 25 mph. Temps will remain below normal with highs ranging from the 60s across north central WI to the 70s over central and eastern WI. It will remain on the muggy side across eastern WI ahead of the front, with more comfortable conditions arriving from west to east through the day. Severe Storm Potential & Increasing Heat/Humidity This Weekend: Most/all of Saturday is looking dry as high pressure shifts into the eastern Great Lakes. However, will need to monitor for a dying complex early in the day, then more shower/storm develop later in the day along a weak frontal boundary lingering across the state, as some of the CAMs want to initiate of activity along it, but won`t bite on that just yet. More widespread shower and storm development is expected to our west Saturday PM/night where the LLJ interacts with the frontal boundary and a large pool of CAPE over 3000+ J/kg. This area/complex looks to be organized enough to move into parts of central and/or north central WI late Saturday into Sunday morning, but likely weakening as it tracks east. Some gusty winds and heavy rain would be the main threats. Attention then turns to Sunday as a mid- level trough digs into the northern Plains and a cold front tracks across the state. Impressive instability forecast to build ahead of the front, with 3000-4000 J/kg of SBCAPE. Deep layer shear is still forecast to be on the weaker side (20-30 kts), especially the further south you go, which would hinder better organization. But up to 40 kts of shear could be realized later in the day across central and north central WI, which would favor supercells and bowing segments and an organized severe weather event (with all hazards possible). AI/ML convective outlooks continue to highlight our area as well. SPC has placed much of the area in a Slight Risk for severe storms on Sunday, which seems very reasonable given the strong instability. Temps and humidity levels will be on the rise this weekend as south flow prevails across the western Great Lakes. Highs in the upper 70s and low 80s (away from Lake Michigan) are expected on Saturday with humidity levels climbing through the day. A warm and humid day on Sunday is expected with highs in the 80s to around 90 with dewpoints in the mid 60s to low (possibly mid) 70s, producing heat index values in the low to mid 90s for parts of central and eastern WI. Flooding: Cancelled the flood watch earlier as the heavier rain exited the area and only lighter rain expected the rest of the morning. Other than some rising rivers (especially the Yellow and Wisconsin) and possible minor flooding due to the recent rain/runoff, no other flooding concerns are expected the rest of the week. Bouts of heavy rain are possible this weekend as PWATs climb back to around 1.5" and at least a round or two of convection is looking more likely. The convection on Sunday will be fairly progressive, which should limit the overall flooding threat. However, if/where any places get multiple rounds of storms and/or training cells, some additional minor flooding concerns. This will be especially the case for locations that received the heavier rain over the past few days. Rest of the Forecast: As the large trough drops across the Great Lakes on Monday, expect some clouds along with a few showers in the northwest/cyclonic flow regime. Models are not in the best agreement the rest of the week, but additional chances for showers and storms look return at times as the boundary will set up somewhere to our west/south. && .AVIATION /18Z TAFS THROUGH 18Z SATURDAY/... Issued at 1210 PM CDT Fri Jun 27 2025 Ceilings should continue to gradually rise this afternoon and scatter out through the evening as weak high pressure crosses the region. With winds becoming light overnight and a cool, moist boundary layer in place, especially across central into north-central Wisconsin, shallow fog may develop, with HREF indicating medium probabilities (40-60%) for IFR fog from KCWA up to KRHI. Fog should quickly erode after sunrise with a return to VFR conditions. Breezy west to northwest winds will become light overnight and then trend southerly on Saturday. && .GRB WATCHES/WARNINGS/ADVISORIES... WI...None. MARINE...None. && $$ DISCUSSION...Bersch AVIATION...JM