


Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI
Issued by NWS Milwaukee/Sullivan, WI
802 FXUS63 KMKX 152048 AFDMKX Area Forecast Discussion National Weather Service Milwaukee/Sullivan WI 348 PM CDT Tue Jul 15 2025 .KEY MESSAGES... - Very warm and humid conditions today into Wednesday with maximum heat indices topping off in the lower 90s. - Increased shower and thunderstorm chances through the day Wednesday (50-80%) with lower chances (20%) lingering into Thursday morning. - Slight Risk (2 out of 5) to see strong to severe thunderstorms Wednesday afternoon/evening capable of gusty winds, hail, and heavy rainfall. - Looking cooler and drier later Thursday into Friday with high temps in the 70s and lows in the 50s to around 60F. - Unsettled weather returns for the weekend with 30-50% shower and storm chances Saturday and Sunday night. && .SHORT TERM... Issued 340 PM CDT Tue Jul 15 2025 Tonight through Wednesday night: High pressure is expected to retreat eastward through the rest of the afternoon and into tonight. Skies will stay mostly clear to partly cloudy overnight with a bit of fog in the Wisconsin River Valley, but some CAMS depict a bit of elevated instability lifting north as warm, moist advection occurs around the western edge of the departing high pressure. A few weak, scattered showers may form on the leading edge of the WAA, mainly along the Wisconsin/Illinois border and southeast Wisconsin (15 to 25% PoPs). This should mainly occur between midnight and 6am before dissipating. Meanwhile to our northwest overnight, outflow from convection over Minnesota and the upper peninsula of Michigan will wash out over the northern half of Wisconsin pushing a nebulous boundary into central WI and portions of central Iowa. Other dying convection will then leave a weak area of low pressure and compact MCV aloft over central Iowa by daybreak on Wednesday. Through the remainder of the morning, and into the early afternoon, this area of low pressure is expected to deepen and track east, advecting a very humid sfc airmass northward during the late morning and passing over Wisconsin during the afternoon into the evening. Sfc pressure falls, the MCV/shortwave aloft, and a few surface boundaries will all work to kick off shower and storm activity near the Mississippi Valley shortly after noon. These storms will then move over southern Wisconsin from west to east between 2pm and 8pm. CAMs depict an environment with moderate SBCAPE around 2500 J/kg, with mid level lapse rates ranging from 6.5 to 7 C/km. Effective shear will be around 35 knots and boundary perpendicular over most of the area, promoting storm organization and a semi-discrete mode. Hodographs do show some low level curvature from 0-2km, but flow will be lacking aloft, likely lending an HP/linear mode to any storms that form. With some dryness in the low levels, a damaging wind threat may develop, especially with any linear/bowing storms tomorrow. More discrete storms, on the other hand may have a short lived hail threat. Additionally, PWATS will be between 1.75 and 2 inches, meaning any storms tomorrow will produce heavy downpours. Urban and small stream flooding may occur over central to east central WI, where a larger area of precip is expected to form near the surface low center and more training of convection is anticipated to happen. CMiller && .LONG TERM... Issued 343 PM CDT Tue Jul 15 2025 Thursday through Tuesday: The sfc low is expected to drag a cold front over the region and wrap in dry air from the northwest Wednesday night into Thursday. Some showers may linger Thursday morning, but a very welcome reprieve is then expected Thursday afternoon into Friday as dry, cool air moves over the Upper Midwest with relatively strong high pressure. Highs are expected to be around 70 on Thursday, and in the mid 70s Friday. Temperatures slightly rebound this weekend as weak WAA returns over the Upper Great Lakes region. Shower and thunderstorm chances return on Saturday as a sfc trough moves over the region. This trough should largely pass Saturday night, keeping most of Sunday dry, but more shower and thunderstorm chances may return Sunday night as a wave of warm advection returns from the Plains. Warmer and more humid conditions then return by the end of the extended period. CMiller && .AVIATION... Issued 322 PM CDT Tue Jul 15 2025 VFR conditions will continue into tonight over most of southern WI. BKN040 daytime cu is expect to dissipate after sunset with areas of fog possible around and in the Wisconsin River Valley overnight. Winds will remain mostly southwesterly and light to moderate, while areas along the lakeshore will see southeasterly winds behind a lake breeze, until the circulation ceases after sunset. Tomorrow, scattered thunderstorm activity capable of gusty winds, appear possible over all of southern WI between 19Z and 01Z Thurs. CMiller && .MARINE... Issued 322 PM CDT Tue Jul 15 2025 A slow moving front will approach Lake Michigan from the northwest tonight as high pressure retreats east toward the east coast. Low pressure will then approach lake Michigan from the Iowa/Minnesota border by Wednesday evening, bringing chances for thunderstorms over most of the lake. Winds will remain southerly and light to moderate over most of the lake through tonight, until the front sinks south over the lake during the post dawn hours tomorrow. The front will then stay stationary over the lake with north winds over the northern half and south winds over the southern half of the Lake into Wednesday night. Winds will then come around to northwesterly following the passage of the surface low Wednesday night into Thursday morning. Gusty winds are then expected Thursday as the pressure gradient gets squeezed between the departing low pressure, and strong high pressure over the northern plains. CMiller && .MKX WATCHES/WARNINGS/ADVISORIES... WI...None. LM...None. && $$ Visit us at weather.gov/milwaukee Follow us on Facebook, Twitter, and YouTube at: www.facebook.com/NWSMilwaukee www.twitter.com/NWSMilwaukee www.youtube.com/NWSMilwaukee