NWS Milwaukee Forecast Discussion
328 FXUS63 KMKX 111002 AFDMKX Area Forecast Discussion National Weather Service Milwaukee/Sullivan WI 502 AM CDT Sat Apr 11 2026 .KEY MESSAGES... - Patchy fog over south-central Wisconsin through daybreak. - Highs in the 50s Saturday before 70s return Sunday and into next week. - An active weather pattern returns late this weekend into next week. Warm and humid conditions and more showers and storms are expected. Severe storms will be possible, especially for Monday and Tuesday. && .UPDATE... Issued 500 AM CDT Sat Apr 11 2026 Mostly clear skies prevail early this morning with high pressure centered over Lake Michigan. Resultant light winds & efficient radiational cooling have allowed for some patchy fog development in low-lying spots over the last several hours, with more widespread activity yet to develop given a very shallow layer of moisture near the surface. Thus thinking that any patchy fog will remain confined to low-lying spots through daybreak, but will continue to watch trends. Regional radar shows a scattering of rain showers ongoing over north-central Iowa at the current hour. Activity is ongoing within a belt of warm/moist advection rooted near the 700 mb level, and is progged to attempt to work eastward through mid to late morning. Have thus maintained slight chance to chance precip probabilities during the late morning and early afternoon hours, but do think that activity will struggle to reach the surface as it encounters drier air in place in the wake of departing high pressure. Will be monitoring radar trends and adjusting the forecast as necessary. Widespread shower potential settles in this evening as deeper warm advection and moisture work into the region. Initial activity will be displaced from any appreciable elevated instability, though some rumbles of thunder could gradually mix in during the second half of the night as MUCAPE starts to increase. Not expecting severe weather potential in this activity, but will need to monitor any storms north and west of Madison for some small hail. Quigley && .SHORT TERM... Issued 1115 PM CDT Fri Apr 10 2026 Current Overnight through Sunday Night: Patchy fog is expected to develop tonight as subsidence will trap some marginally higher dewpoints from an afternoon lake breeze near the surface. This fog is expected to mainly occur over south central to southwest Wisconsin. Otherwise, high pressure will linger over the region through the morning, with fog dissipating after sunrise. Clouds are expected to increase as upper level warm advection spreads across the region. During the afternoon, some attempts at light rain may occur, but we may not reach full saturation due to some dry air from the high pressure lingering at the surface. As we head later into the afternoon, low levels should steadily moisten and rain will become more likely Saturday evening into Saturday night. The warm advection aloft will cause some weak MUCAPE to build to 500 J/kg and some rumbles of thunder may occur early Sunday morning. On and off showery rain and rumbles of thunder are then anticipated to continue through Sunday into Sunday night as warm advection continues over the region and a sfc warm front lifts north across the state. Even with clouds and showers, high temperatures near 70 are forecast for Sunday. That warmer surface air will be ushered into the area on gusty southwest winds to 35 mph. CMiller && .LONG TERM... Issued 1152 PM CDT Fri Apr 10 2026 Monday through Friday: Multiple days of strong to severe storms appear possible to start the work week as multiple waves are expected to propagate along the warm frontal as it stalls over the region. Monday`s storm threat still remains in question, as runs of the RRFS, NAM, GFS, and ECMWF all widely disagree on where storms will initiate on Monday, though a more recent trend with the evening 00z runs favors storms firing along the warm front over north central MN into northern WI, which would largely spare us. Details have then become clearer pointing toward Tuesday as the day with the best potential for severe storms, as a sfc low tracks northeast over Iowa and central Wisconsin. CSU MLP probs include a sig severe contour over our area for this time period. Synoptically, an overlap of sfc moisture, with lift from the surface low and stationary front, and great kinematics from a strong 850mb jet aloft will likely cause a day where all severe hazards will be possible, though some details regarding morning convection need to be hammered out, as the RRFS suggests there may be some around daybreak on Tuesday. Any morning convection may shift/hamper the overall severe risk owing to an inability to recover instability. Depending upon how Tuesday evolves and the positioning of a cold front, Wednesday may then feature more chances for severe weather during the afternoon until the cold front passes. Beyond, the CAA behind the cold front will be weak, and warm advection from another approaching system will quickly allow us to recover into the 70s on Thursday. Models suggest additional chances for rain/storms late week as a trough approaches the state from the northwest. CMiller && .AVIATION... Issued 500 AM CDT Sat Apr 11 2026 VFR flight categories prevail across the majority of the region this morning. Pockets of fog have developed in the vicinity of JVL, resulting in occasional VIS reductions at the field. Have accounted for these trends in the 09Z and 12Z updates. Still can`t rule out some patchy fog development in the vicinity of MSN through daybreak, though any such development will be short-lived. Mid-upper clouds will gradually build in from the west today. Could see an isolated shower from late morning into the afternoon hours, though anticipated widely scattered coverage makes confidence far too low to justify any mentions in the 12Z update. Will monitor radar trends and insert TEMPO/prevailing groups if necessary. More widespread -SHRA will overspread southern Wisconsin this evening, with -TSRA possible after midnight along and north of I-94. Precip will be accompanied by reduced CIGs and eventual categorical reductions. Expect LLWS at all terminals after midnight as the low level jet increases regionally. Quigley && .MARINE... Issued 1122 PM CDT Fri Apr 10 2026 High pressure will linger over the Upper Great Lakes Region through this morning, with light and variable winds continuing. Southeast winds return this afternoon and become gusty tonight as a sharper pressure gradient moves over the lake as low pressure moves into the northern Great Plains. Low pressure will shift into the northern Great Plains during the day Sunday as it deepens. The low will quickly shift east toward Lake Superior Sunday night, reaching the southern shores of the Hudson Bay by daybreak Monday morning. Winds will thus increase further across the open waters Sunday through Sunday night. Will be monitoring for gale potential during this time frame, particularly over the northern half of Lake Michigan. As of this forecast update, forecast models continue to suggest possible gales and headlines may be needed in the coming days. Winds will weaken Monday morning as high pressure moves across Ontario. Then, passing low pressure systems will lead to persistently active conditions across Lake Michigan into next week. Will need to monitor thunderstorm development during the Monday- Wednesday time period, as some storms could become strong to severe. CMiller && .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