Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI
Issued by NWS Milwaukee/Sullivan, WI
980 FXUS63 KMKX 301914 AFDMKX Area Forecast Discussion National Weather Service Milwaukee/Sullivan WI 214 PM CDT Thu Jul 30 2026 .KEY MESSAGES... - Increasing chances for showers and weak thunderstorms at times from Friday morning through Friday night (80-95% chances). Chances gradually taper down through Saturday. - Breezy onshore winds will lead to high waves and dangerous currents at Lake Michigan beaches this weekend, with Moderate to High Swim Risk conditions possible Saturday and Sunday. && .SHORT TERM... Issued 200 PM CDT Thu Jul 30 2026 Tonight through Saturday: Dry weather continues for the rest of today through tonight, with high pressure overhead shifting southeast into the Ohio River Valley. Simultaneously, a positively-tilted 500mb trough swings southeastward across the upper Midwest. Corresponding surface low pressure deepens over IA on Friday and continues east through IL on Saturday. The slow-moving nature of this low coupled with steady isentropic upglide through its precip shield and ~2" PWAT values will make it a very efficient rain-maker for portions of the midwest. The exact track of the system (further north/south in IA and IL) will heavily influence the amount of rainfall we get here in southern WI, and a sharp cutoff between a few light showers (further north) and a drought-busting long-duration rainfall (further south and west) could easily set up near or within our CWA. That said, model guidance is beginning to converge on the system track. Regardless of the track of the low, we don`t expect strong to severe thunderstorms in southern WI given the lack return flow and limited MUCAPE (most guidance 500 joules or less). The only concerns would be the potential for localized heavy rainfall (level 2 out of 4 risk along and west of the I-90 corridor) and a chance for lightning. A gradual southwest to northeast arrival of rain chances unfolds through the daytime hours on Friday. Activity would then peak in intensity / coverage later Friday through Friday night, and slowly diminish through Saturday. Breezy onshore winds associated with the low will lead to Moderate or High Swim Risk conditions on Lake Michigan beaches late Friday night through this weekend, especially from Milwaukee county southward. Sheppard && .LONG TERM... Issued 200 PM CDT Thu Jul 30 2026 Saturday night through Thursday: Dry weather expected Sunday into Monday as high pressure settles over the upper Great Lakes. Temperatures begin a gradual uptrend early next week as a ridge in the upper jet builds east into the region. The warmth would likely peak on Tuesday as the upper ridge axis passes, with high temperatures in the mid to upper 80s possible, with dewpoints in the upper 60s to around 70. An approaching longwave trough will allow some diffluent flow to overspread the region Tuesday PM (10-20% shower/storm chances), intensifying Tuesday night into Wednesday as the right entrance of an associated jet streak passes by (25-35% shower/storm chances). The surface pressure response to these features is certainly not looking organized on model guidance, hence our confidence in rainfall with it remains low. The longwave pattern in the jet looks to remain predominantly zonal through next week, suggesting mostly dry weather and near normal to slightly above normal temperatures (highs in the low to mid 80s) for late next week. That said, the proximity of the jet and smaller perturbations within it merit some continued ~25% precip chances into Thursday. Sheppard && .AVIATION... Issued 200 PM CDT Thu Jul 30 2026 Dry weather and VFR continue today and tonight. Wildfire smoke aloft may lead to haze in the sky at times today and tonight, but only trace amounts of it will reach the surface, and surface visibility should remain 6 SM or greater. Upper-altitude clouds (over 20,000 ft) will increase in coverage overnight into early Friday. Low pressure will track across Iowa Friday and Illinois Saturday. A southeast breeze is expected as it approaches Friday, with rain chances gradually increasing from west to east throughout the day. Cloud ceilings gradually decline, but are forecast to remain at generally VFR levels through Friday afternoon and evening (with the exception of far southwestern WI, where some Fuel Alt MVFR or IFR may arrive early). A few thunderstorms will be possible with this activity, but no strong or severe storms are expected. Sheppard && .MARINE... Issued 200 PM CDT Thu Jul 30 2026 Light and variable winds will take on a southerly component this afternoon as high pressure around 30.0 inches starts to drift toward the Lower Great Lakes. Low pressure around 29.7 inches will track across Iowa Friday and through Illinois Saturday. The approaching area of low pressure will bring chances for showers and a few thunderstorms Friday into Saturday. Severe weather is not expected in any of this activity. Breezy northeast winds will develop Saturday and should continue through Sunday as high pressure of 30.0 inches builds over Lake Superior. A few gusts upwards of 30 kt will be possible over the southern half of the lake. For nearshore zones from Sheboygan to Winthrop Harbor, the gusty northeast winds and building waves are likely to reach Small Craft Advisory levels at times Saturday through Sunday night. Sheppard && .MKX WATCHES/WARNINGS/ADVISORIES... WI...None. LM...None. && $$ Visit us at weather.gov/milwaukee Follow us on Facebook, X, and YouTube at: www.facebook.com/NWSMilwaukee www.x.com/NWSMilwaukee www.youtube.com/NWSMilwaukee