537 FXUS63 KGRB 051846 AFDGRB Area Forecast Discussion National Weather Service Green Bay WI 146 PM CDT Fri Jun 5 2026 Forecast discussion for routine afternoon forecast issuance .KEY MESSAGES... - Scattered showers and storms are expected to cross the area from west to east through this evening. Some storms could become strong or severe, with damaging winds and up to 1" hail being the main concerns. - Warm moist air moving across Lake Michigan will bring a period of marine dense fog across the nearshore zones, which may affect boaters. - Above normal temperatures persist for the next week. High temperatures in the 90s along with humidity will increase the potential for moderate to major heat- related impacts. && .DISCUSSION... Issued at 146 PM CDT Fri Jun 5 2026 Storms This Afternoon/Evening... Active weather will be the main focus of the forecast today. Upstream development in Minnesota associated with a mid-level shortwave is readily visible on both satellite and radar; and this will be the main feature to watch for any stronger storm development. Instability ahead of this feature has proved sufficient for some isolated convection, mainly in the Upper Peninsula, but will need to watch for at least isolated convection developing out of the cumulus field across the northwoods. As the storms progress into the region, modest lapse rates, weak shear, and convergence along the shortwave could serve to provide a brief hail threat, mainly limited further west where instability and lapse rates will be greatest as the shortwave arrives. Wind then becomes the more likely threat further east as scattered thunderstorm activity heads into the and through the Fox Valley, with CAMs suggesting the possibility of some brief bowing segments embedded in scattered thunderstorm activity. Timing on storms remains fairly similar to previous forecasts, with an arrival in the mid to late afternoon for central and north-central Wisconsin, and more of an evening timeframe for the Fox Valley. PWATs during this time period remain fairly high (>1.5"), so moderate to heavy rainfall will be possible within any convection., which may also make for some fairly high localized rainfall totals for areas that see the stronger storms. High end amounts could produce spots with over an inch of rainfall. Fog... Fog over the marine zones will be in place this afternoon and evening as the warm and moist airmass lifts northwards. Would expected improvement as winds shift ahead of and along the convection that will arrive from the west. Temperatures... Above normal temperatures will persist through the weekend into next week, but a surge of even warmer temperatures will likely (60-80% chance) bring high temperatures into the 90s by the middle of next week. As this will be a several day stretch of warm high temperatures and low temperatures also remain in the 60s, heat related impacts are expected to see a major increase next week. Warmest periods look to be Wednesday and Thursday afternoons, where some of the higher potential heat indices are forecast to exceed 100 degrees across portions of central Wisconsin to the Fox Valley. Though still too soon to say with certainty, will need to monitor the potential for headlines as we head into early next week. Extended... Accompanying the heat and humidity next week will be a reservoir of instability that builds over much of the upper Midwest. However, predictability for any rain/storm chances remains low this far out as mid-level ridge sits right overhead. Most of the ridge rider activity looks to stay off to our west, so convective initiation in our neck of the woods would likely hinge on smaller scale forcing mechanisms given the general absence of upper support. This being said, cannot rule out periodic chances for some stronger diurnal storms given the magnitude of destabilization likely to occur during peak heating. && .AVIATION...for 18Z TAF Issuance Issued at 1257 PM CDT Fri Jun 5 2026 Lingering MVFR/VFR stratus and cumulus clouds will affect portions of the region through the afternoon, especially along the Lake Michigan shoreline and in north-central Wisconsin where increasing instability has brought back some additional cumulus formation. A round of rain and thunderstorms is then anticipated to cross the region in the late afternoon and evening from west to east, crossing into Wisconsin out of Minnesota. A few stronger storms may be embedded within the line, with some hail potential in the early afternoon turning to mostly a wind gust concern by the time the storms reach the Fox Valley and lakeshore TAF sites. Exact location of the stronger storms remains more uncertain at this time, so kept the PROB30 group for now, but would expect to see changes over to TEMPO and possibly prevailing as the storm trajectories become more certain over the next TAF issuance. Behind the storms, currently expect some clearing and better flying conditions going into Saturday, so have VFR return by the morning hours. && .GRB WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION.....Uhlmann AVIATION.......Uhlmann