Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI
Issued by NWS Milwaukee/Sullivan, WI
266 FXUS63 KMKX 242055 AFDMKX Area Forecast Discussion National Weather Service Milwaukee/Sullivan WI 355 PM CDT Tue Jun 24 2025 .KEY MESSAGES... - Scattered thunderstorms will continue into this evening, with stronger storms featuring gusty winds and heavy downpours. - Potential for stronger thunderstorms develop again Wednesday night and Thursday afternoon, with the main threat local flooding and gusty winds. - Multiple rounds of thunderstorms will continue through Thursday, with a high chance (70 to 80 percent) of exceeding an inch of rainfall in southwestern to south-central Wisconsin. This may lead to localized flooding underneath heavier thunderstorms. - Rivers are currently rising, with additional rounds of rain and storms bringing potential for some areas reaching flood stage over the next few days. - A return to higher heat and humidity expected going into the weekend. && .SHORT TERM... Issued 355 PM CDT Tue Jun 24 2025 Tonight through Wednesday night: Slow moving scattered thunderstorms will continue across the region into this evening before losing ice crystals and therefore lightning potential. An isolated storm may become strong, with gusty winds and local downpours the main threats. Pattern remains dominated by a very weak frontal feature that will continue to act as a source of ascent through tonight and into Wednesday and Wednesday night. However, shear remains very low at only 15 to 20 kt between the surface and 500 mb. This prevents storms from moving rapidly and keeps cloud cover firmly in place across southern Wisconsin, thereby limiting the amount of instability available for developing thunderstorms. Therefore not anticipating more than an isolated stronger storm tonight, with mainly showers expected overnight into Wednesday morning. There will be long periods of breaks in thunderstorm activity, but due to very weak forcing and a diffuse boundary, timing and placement of these breaks remain highly uncertain. Wednesday, a return to more organized convection is possible. An MCS looks to develop along the apex of the LLJ in northern Nebraska, with its cold pool propagating northeastward and becoming the main trigger for convection in southern Wisconsin going into Wednesday afternoon and Wednesday night. In addition, low pressure will eject into the Upper Midwest from the central High Plains, bringing additional shear (35 to 45 kt surface to 500 mb), producing frontogenesis along the lingering boundary and increasing mid-level instability (MUCAPE around 2000 J/kg). With all these considerations, strong storms with gusty winds and heavy rain (PWATs between 1.75 and 2 inches) are becoming more likely Wednesday evening into Wednesday night. Rivers are already rising from previous rainfall. A few rivers may exceed flood stage going into Wednesday night and Thursday morning. MH && .LONG TERM... Issued 355 PM CDT Tue Jun 24 2025 Thursday through Tuesday: Thursday into Thursday night, as surface low pressure lifts into southern Ontario, expect a cold front to propagate southeastward across southern Wisconsin. This will act as the primary trigger for a final round of rain and storms through this time period. Surface based CAPE around 3000 J/kg currently being projected by modeling implies quick-developing storms, while PWATs around 2 inches continue and shear between 25 and 30 kt lead to slower-moving storms capable of continuing flooding concerns. Generally unidirectional shear indicates primary hazard once again to be gusty winds and microbursts under stronger storms. This cold front will push southeastward out of the area by Friday morning. Continued rainfall may exacerbating flooding concerns. General ridging pattern then sets back up across the Great Lakes region going into the weekend, bringing high temperatures in the upper 80s to near 90 degrees and heat index values in the upper 90s. Ridging will be shortlived this time, however, with frontogenesis between a surface low in the Hudson Bay and a second surface low developing in the lee of the Colorado Rockies producing widespread convection across Wisconsin and into the central Plains and Ontario. This front will sag southeastward into Monday, leading to additional rain and storms, before exiting into Tuesday. Seasonable temperatures in the lower 80s are expected Monday and Tuesday. MH && .AVIATION... Issued 355 PM CDT Tue Jun 24 2025 Slow moving scattered thunderstorms will continue across the region into this evening, losing lightning potential into tonight. An isolated storm may still become strong, with the main hazard gusty winds. Due to a very weak front, there will be long periods of breaks in thunderstorm activity tonight into Wednesday morning for each individual terminal, but timing and placement of these breaks remain highly uncertain. With higher than usual uncertainty of development and placement, PROB30 groups have been used more liberally for the TAF period, with expectation to amend as environment dictates. Light and variable winds continue through tonight, with lowering ceilings expected. IFR conditions may become dominant by the early morning hours Wednesday, with showers becoming more widespread as the frontal boundary intensifies with low pressure developing to the southwest. Scattered storms are expected to develop along the boundary going into Wednesday afternoon, producing gusty winds within the strongest storms. MH && .MARINE... Issued 355 PM CDT Tue Jun 24 2025 A weak, nearly stationary frontal boundary will linger across the southern third to southern half of the lake through Thursday, bringing multiple rounds of thunderstorms to the southern half of the lake. Isolated thunderstorms are also possible across the northern half. Expecting modest northeasterly winds north of the frontal boundary, with modest southeasterly winds south of the boundary. Thursday night, expecting the front to lift northward ahead of approaching low pressure, bringing south southwest winds to the open waters. As low pressure exits to the east, expect a wind shift to westerly on Friday into Friday night. MH && .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