textproduct: Milwaukee/Sullivan

KEY MESSAGES

- Scattered showers and storms remain forecast Monday night. A few storms could be severe, with large hail being the primary threat.

- Additional showers and storms are forecast Tuesday afternoon, with exact areas of development depending on early day clouds & rain. A few storms could be severe, with large hail and gusty winds being the primary threats.

- Chances for wintry mix Wednesday evening into Thursday morning.

- Additional chances for rain & a few thunderstorms Thursday afternoon into Saturday.

UPDATE

Issued 700 PM CDT Sun Mar 29 2026

Quiet tonight with a period of clearing with some high clouds pushing in later tonight. High pressure will continue to push out with lower pressure nudging in from the west. Modest southerly winds will continue overnight into Monday morning. A piece of the low pressure will eject off the main low tonight and drive the front southward into parts of southern WI into Monday morning. This will likely bring a fairly sharp temperature gradient through Monday as breezy southwest winds to the south will push temperatures into the upper 60s to mid 70s at least with areas north of the front working in conjunction with the lake breeze will bring areas in east central WI and near the lake to as low as the low 40s to mid 50s. However, there should be time in the morning for most areas to warm up to the 60s before the impact of the front/lake breeze will be felt.

Kuroski

SHORT TERM

Issued 248 PM CDT Sun Mar 29 2026

This Afternoon through Monday night:

Synopsis/Mesoanalysis: Low pressure is centered over central Nebraska this afternoon. A surface front extends northeast of the low, with current obs showing the boundary along an approximate Watertown, SD - Saint Cloud, MN - Ironwood, MI line. While currently stationary, the front is expected to advance southeast tonight as high pressure builds into the northern plains. The front is forecast to move into central Wisconsin by daybreak, setting up near or just north of far northern locations. Generally southerly winds will halt the front's progress during the day Monday, allowing for warm high temperatures across southern Wisconsin. Warm conditions will allow for a strong lake breeze to advance inland, resulting in falling temperatures during the late afternoon & early evening in southeast and east-central Wisconsin. Forecast guidance shows the advancing lake breeze & central Wisconsin surface front merging into one effect frontal feature Monday evening, with the boundary settling somewhere over the southern half of the state Monday night. Lift in the vicinity of the boundary, in addition to isentropic ascent within an increasing overnight low level jet, will support scattered shower and thunderstorm development Monday evening & night, with a few strong to severe storms possible. The front will gradually work through the area on Tuesday, and could trigger additional shower and storm development through the early to mid afternoon hours. Conditions will trend much quieter as the front departs Tuesday evening & night.

This Afternoon: Pockets of elevated fire weather conditions continue through peak heating. Moisture recovery has been slow to occur this afternoon, with deeper returns expected to hold off until overnight tonight. Fuels continue to trend on the moist side, which will preclude more widespread fire weather conditions from materializing. No Special Weather Statements are thus planned in the afternoon forecast update.

Tonight: Will need to monitor for some patchy fog potential across northern areas if the surface front manages to make it into the CWA. Weakening winds immediately in the vicinity of the boundary could allow for some decoupling and visibility reductions closer to daybreak. Not anticipating any fog to be dense in the event it develops.

Monday night into Tuesday morning: Continue to monitor for the first of two potential rounds of showers/storms. Precise locations of storm development, in addition to coverage of storms themselves, remain uncertain as evidenced by the 12Z Sunday suite of CAM guidance. Evolution of the surface pattern---specifically the primary front over central Wisconsin, the afternoon lake breeze, and the single boundary that they consolidate into---is likely to be the key influence on where convection fires during the evening/overnight, as an overlap of deeper frontogenesis & increasing isentropic ascent will provide the best support for storm development along/north of where the boundary sets up. A loose consensus of high-res solutions suggests that this will be favored along/north of I-94 & US-18, though additional shifts in modeling will be possible all the way into Monday afternoon. Will thus need to monitor modeling & observational trends over coming updates & adjust the PoP forecast as necessary. Regardless of where/when storms form, an overlap of building MUCAPE, steep mid-level lapse rates, and sufficient deep layer shear will support organized storm potential & some attendant strong/severe threat. Given the likely elevated nature to storms, continue to expect that large hail will be the primary hazard. Can't rule out a few stronger wind gusts if downdrafts can get through to the surface, with greatest potential being closest to the surface front/where the surface layer will be least capped. Heavy downpours will also accompany any storms, though flooding concerns appear low given progressive storm motions & lack of training signal in model guidance. Will continue to monitor for any changes.

Tuesday: Will be watching for a second round of showers/storms during the early-mid afternoon as the surface front departs to the south and east. Development will hinge on how fast/slow the front moves through southern Wisconsin, which is likely to be influenced by earlier day cloud cover and rain. The later into the day/peak heating the front lingers, the better the chances for additional storms. Currently appears that south-central and southeast Wisconsin will stand the greatest potential of seeing a second round of storms, though trends will need to be monitored given the number of uncertainties in play. A few strong/severe storms would be possible in this second round of development, with large hail and damaging winds being the primary hazards.

Quigley

LONG TERM

Issued 248 PM CDT Sun Mar 29 2026

Wednesday through Sunday:

A cold airmass correlated with dense high pressure settles into Ontario as the main cold frontal boundary stagnates across the Ohio Valley and its parent low exits into the Northeast U.S. Meanwhile, the remnants of the frontal feature in the central Plains look to phase with a 500 mb shortwave ejecting eastward through the southern Rockies, deepening the surface low associated with the shortwave in the southern High Plains. This low will begin to produce strong WAA across the Mississippi Valley in the low to mid- levels Wednesday night, bringing overrunning precipitation to southern Wisconsin (50-70% chances).

Ahead of this precipitation, temperatures in southern Wisconsin are expected to rise into the upper 30s to low 40s, but this will be in a shallow layer near the surface due to continued CAA through the column and solar heating of the surface. Expecting initial showers to begin as rain Wednesday evening due to warm surface temps. Temperatures are then expected to fall into the low 30s overnight Wednesday, but whether they fall below freezing remains in question. With increasing WAA around 850 mb, a period of sleet is possible even with temperatures near the surface remaining just above freezing. In areas that do fall below freezing along and south of I- 94, a period of freezing rain is possible as the warm nose strengthens toward Thursday morning. Confidence in sleet, snow, and rain is higher than confidence in freezing rain due to surface temperature concerns. Farther north from Sauk to Sheboygan Counties, mainly snow and sleet are expected overnight, with an inch or two of accumulations possible.

As low pressure propagates into southern Illinois Thursday morning, the warm nose will exit the region with CAA becoming dominant at the 850 mb level. Any remaining freezing rain and sleet will become snow, with temperatures rising into the upper 30s after sunrise Thursday morning and allowing snow to transition to rain or a rain/snow mix with minimal additional accumulations. Continued northerly winds will bring temperatures near freezing and drying conditions (~40% chances additional showers) overnight Thursday as low pressure exits.

Another chance for phasing develops Friday in the central Plains as the trailing cold front from the Midwest ejecting low nears the developing warm frontogenesis region of a developing Wyoming High Plains low. Model solutions diverge on the intensity and trajectory of this low, but still in general agreement that an additional round of precipitation will move through southern Wisconsin Friday afternoon as a warm front lifts through the region. Discrepancies become more evident into Saturday as the GFS indicates a northern solution that drags a cold front through the region during the afternoon and the Canadian/ECMWF keep the low much slower and farther south, bringing prefrontal convection potential to southern Wisconsin Saturday afternoon before a cold front later Saturday night. Sunday, all major models indicate Canadian high pressure building through the Upper Midwest, leading to dry conditions and high temperatures in the low 50s.

MH

AVIATION

Issued 715 PM CDT Sun Mar 29 2026

VFR conditions expected tonight through Monday any clouds are expected to remain fairly high. There are some patchy mid level CIGS in parts of southern WI right now but should dissipate over the next few hours. Otherwise the main concern early in the TAF period is the patchy potential for some LLWS in parts of southern WI this evening/tonight. The best chance for prolonged LLWS is for SBM but shorter periods will be possible elsewhere tonight. The primary concern into the day monday is the presence of the front which, in combination with the lake breeze impact winds in east central WI and closer to the lake. There does remain some uncertain in how far east the lake breeze impacts but MKE and SBM will likely see the impacts of the lake breeze with some chance for UES and ENW as well. Some MVFR CIGS will push into central WI Monday night with increasing chances for showers/storms as CIGS likely lower across most of southern WI by early Tuesday morning. Cannot rule out a strong to severe storm Monday night.

Kuroski

MARINE

Issued 248 PM CDT Sun Mar 29 2026

Breezy southwest winds continue through this afternoon as a cold front begins to approach the waters from the north. The front will gradually advance south across Lake Michigan tonight through Tuesday. This will result in generally east-northeast winds across the northern half of the lake with southerly winds further south. A few gales are possible over southeastern Lake Michigan Monday night, but aren't expected to be widespread. Periods of showers and thunderstorms will accompany the slow-moving front, with a few stronger storms possible Monday night and once again on Tuesday. Large hail would be the primary threat in any stronger storms.

Winds will trend northerly behind the departing cold front Tuesday evening through Wednesday. Will be monitoring trends for a few gusts approaching gale force Tuesday night into Wednesday, with the current expectation being for any such gusts to be isolated. 1040 mb high pressure will shift from Ontario to Quebec through the late week time period as 1010 mb low pressure builds into the Ohio River Valley, allowing winds to trend east-northeasterly. Will need to watch for additional isolated gale potential Thursday into Friday as low pressure passes near or over Lake Michigan, with the continued expectation for any gusts to be too sparse to justify headlines. Will nevertheless be monitoring trends into this week. Additional rain and snow will accompany the approaching/passing area of low pressure Thursday into next weekend.

A few wind gusts may approach Small Craft Advisory thresholds in nearshore zones this afternoon & evening, but aren't expected to be widespread enough to warrant headlines at this time. Trends will continue to be monitored into this evening. Showers and thunderstorms are possible Monday evening/night. A few strong to severe storms remain possible, with large hail and gusty winds being the primary hazards. Additional showers and storms are possible Tuesday as a cold front crosses nearshore zones. Winds will become gusty behind the front Tuesday evening into Wednesday, and are expected to remain elevated through the end of the week. Anticipate that Small Craft Advisories will become necessary during this part of the period, with the need for headlines being addressed in coming updates.

Quigley

MKX WATCHES/WARNINGS/ADVISORIES

WI...None. LM...None.