Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI
Issued by NWS Milwaukee/Sullivan, WI
667 FXUS63 KMKX 310019 AFDMKX Area Forecast Discussion National Weather Service Milwaukee/Sullivan WI 719 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. && .UPDATE... Issued 720 PM CDT Thu Jul 30 2026 Quiet and calm conditions through tonight. An isolated shower across far southwestern Wisconsin cannot be ruled out, but chances are very low (10-15%). Otherwise, expecting increasing cloud cover and light winds. MH && .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 720 PM CDT Thu Jul 30 2026 VFR conditions expected throughout tonight and into Friday, with rainfall developing and progressing eastward through the day Friday. Ceilings are expected to remain VFR, but drops in visibility to MVFR are expected. By Friday evening, expect steady rainfall across all of southern Wisconsin, with isolated embedded lightning. Light and variable winds are expected tonight, becoming southeasterly and increasing to around 10 kt into Friday. Winds will continue to increase into Friday evening. MH && .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