FXUS63 KMKX 151157 AFDMKX Area Forecast Discussion National Weather Service Milwaukee/Sullivan WI 657 AM CDT Wed Apr 15 2026 .KEY MESSAGES... - Additional severe storms possible this afternoon if a front remains stalled across the area. If the front sets up south of the area, severe potential will greatly decrease but flash flooding will remain possible due to training convection. - Heavy rainfall could lead to additional periods of flooding this afternoon into Wednesday. Additional Flood Watches are possible especially tomorrow. - Additional windows for heavy rainfall, flooding, and severe thunderstorms Friday into Saturday. All severe hazards will be possible later Tuesday afternoon into the evening. && .UPDATE... Issued 645 AM CDT Wed Apr 15 2026 Mainly showery precip remains across the region this morning after a low level jet encouraged occasionally strong storm redevelopment through the overnight period. These showers will linger into the at least the first part of the morning hours today, keeping an effective frontal boundary held up over portions of north-central Illinois. If showers vacate early enough in the day, said boundary will attempt to work back into the area during the afternoon, allowing moisture and instability to come back into parts of the region. If this can occur, will be looking at one final round of strong to severe storm development by late afternoon/early evening as an upper wave swings through the region. Despite far more modest mid- level lapse rates relative to yesterday, still favorable speed shear aloft will be supportive for large hail. Damaging winds would be possible as well. An isolated tornado can't be entirely ruled out, though the potential is far secondary to the wind/hail potential & far lower than yesterday. Severe threat aside, any training convection will pose additional flooding potential with the ground saturated and many rivers/creeks either at or above bankfull. Will be monitoring trends through today regarding instability returns & training storm signals in guidance & provide additional updates as necessary. Apart from storm potential, dense fog continues in the northwest through at least mid-morning, where a stalled frontal boundary lingers & surface winds are calm. Dense fog advisory remains in effect until 9 AM, with trends being monitored for possible extensions through mid-morning. Quigley && .SHORT TERM... Issued 1001 PM CDT Tue Apr 14 2026 Overnight through Wednesday: The elevated environment will remain unstable as we remain in the warm sector with upper divergence, weak vorticity advection, and mid level warm air advection overhead. This will allow for a few storms to percolate across portions of central and southern WI overnight. Given the lingering high MUCAPE, a few storms could approach marginal severe levels at times and bear watching. The threat will wane as the night goes on and as the LLJ veers. The effective surface boundary should be stationed over northern IL Wednesday morning as a weak mid level shortwave trough tracks across the region. Southern WI may see scattered showers and a few thunderstorms with the overriding of the boundary in the morning and midday Wed. A deeper shortwave trough will track across NE Wed morning and into western IA by early evening. The associated surface low on the leading edge should help lift that boundary into southern WI during the late afternoon and evening hours. Storms within the warm sector will have the potential for severe-level hail and wind. Heavy rain is a threat with this system. We may need an areal flood watch. Meanwhile, there will be a steady northeast wind off Lake Michigan and keep the air stable with low clouds and patchy fog, especially north of Milwaukee. How far inland the fog/stratus get Wed morning is still uncertain. Wherever the boundary between the lake air and the warm, unstable air lands Wed afternoon, this will be an extra focus for low level helicity and the potential for a brief tornado along this boundary if storms become strong enough. Cronce && .LONG TERM... Issued 1001 PM CDT Tue Apr 14 2026 Thursday through Tuesday: That deeper shortwave trough that went across IA Wed night will track across southern WI Thursday morning. Scattered showers and a few thunderstorms are expected with this feature, especially in the morning with deeper moisture still in place over the region. The chance for showers and thunderstorms will linger into the afternoon. As the deeper moisture departs during this time and we heat up, the low level lapse rates will increase to allow for instability (up to 1000 j/kg) to develop. A lake breeze should push inland and help to trigger some of the showers/storms. Look for the precip chances to exit by sunset. High pressure will pass through Thursday night and lows will dip into the 40s wherever the lake breeze hit, so bisecting southern WI from east to west. Friday morning and early afternoon look quiet, but we will be getting primed for the next system to arrive Friday late afternoon and night. Low pressure tracking across the northern Plains on Friday, in response to a high-amplitude upper trough, will cross Lake Superior Friday night. A strong cold front will slide across WI from west to east late Friday night through Saturday morning. Showers are thunderstorms are expected within the warm sector Friday afternoon/evening and also along the cold front. Scattered showers are possible behind the front during the day Saturday. Strong cold air advection will follow, so low temps should dip down to around or below freezing Saturday night on brisk westerly winds. The models dry out the atmosphere quickly, but if there happens to be any lingering moisture, the precip type would chance to flurries/snow. Brisk westerly winds will persist through Sunday. Finally, high pressure will dominate and give us dry weather through Monday or Tuesday. The weather pattern has a large degree of uncertainty beyond Monday between the models. Cronce && .AVIATION... Issued 645 AM CDT Wed Apr 15 2026 Rain exits late this morning, with additional shower and storm development possible later today. Reduced CIGs and VIS readings will accompany storms. Quigley && .MARINE... Issued 1001 PM CDT Tue Apr 14 2026 A stationary front will remain parked over the middle third of the lake into tomorrow, slowly sinking south to the southern end of the lake by Thursday morning. Winds will remain southerly south of the front and modestly breezy, while winds north of the front will remain light and variable to northerly during this time. The front will clear the lake as a cold front Friday, before low pressure of 29.6 inches approaches from the west. Thunderstorms are possible over the southern third overnight into Thursday morning, then Thursday late afternoon and night. Thunderstorm chances return along a cold front Friday night. Cronce && .MKX WATCHES/WARNINGS/ADVISORIES... WI...Dense Fog Advisory...WIZ046-WIZ047-WIZ056-WIZ057 until 9 AM Wednesday. LM...Dense Fog Advisory...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563- LMZ565-LMZ567-LMZ643-LMZ644-LMZ645-LMZ646-LMZ669-LMZ671- LMZ673-LMZ675-LMZ777-LMZ779-LMZ868-LMZ870-LMZ872-LMZ874- LMZ876-LMZ878 until 7 AM Thursday. && $$ 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