textproduct: Milwaukee/Sullivan

KEY MESSAGES

- Widespread frost and below freezing temps expected inland from Lake Michigan tonight/Friday morning and again Friday night/Saturday morning. Frost Advisory and Freezing Warning in effect for portions of southern WI.

- Scattered showers continue this afternoon into the evening. Additional pop-up scattered showers will be possible on Friday.

- More active pattern early next week with increased showers and storm chances later Sunday through midweek.

SHORT TERM

Issued 200 PM CDT Thu Apr 30 2026

Tonight through Friday night:

Upper-level northwesterly flow pattern continues to influence the pattern across southern WI this afternoon/evening into Friday. This will continue to bring below normal temps as well as a series of mid- level waves bringing bouts of scattered showers into early this evening and again on Friday.

Continue to track the ongoing upper-level wave over IA/southwest WI bringing scattered light showers early this afternoon. It has hit the lake breeze boundary and reflectivity has blossomed over southeastern WI. Expecting this scattered shower activity to continue into the early evening. Watching another wave sitting to our north gradually work southward and likely to merge with the southern one for additional shower development later this afternoon/ evening for our east-central counties of WI. Again not expecting much in the way of QPF ranging from a few hundredths to few tenths of an inch where showers persists.

This round of upper-level waves and scattered showers then look slowly work their way eastward later this evening allowing for calm winds and chillier temps to settle across much of southern WI overnight. Looking at temps in the lower 30s with a few locations evening dipping into the upper 20s under any clear conditions, especially for central WI counties, while cloud cover and lingering showers may insulate eastern areas longer with mid to low 30s. Nevertheless, conditions remain favorable for frost development, especially for inland southern WI tonight into early Friday morning. Given the trend last night and higher confidence in clearing have issued a Freeze Warning for the northwest corner of the CWA and a Frost Advisory the remainder of the inland counties. Areas along the lake may stay just warm enough, especially with lingering cloud cover to limit widespread frost.

Friday is looking fairly similar with the prevailing upper- northwesterly flow bringing cooler temps to southern WI as the center of high pressure tries to build down into the region. While additional mid-level waves are progged to work across the area, the drier airmass ahead of the high pressure may limit the scattered shower activity more than previous days, but still is enough of a signal to maintain lower end PoPs through the day. Again chillier temps, calm, and clear conditions with the high pressure will support frost development across much of southern WI again overnight into early Saturday morning. Thus additional frost/freeze headlines are likely during this time as well.

Wagner

LONG TERM

Issued 200 PM CDT Thu Apr 30 2026

Saturday through Thursday:

With high pressure sitting overhead for Saturday, expecting cooler than normal temps to continue, but enough subsidence and dry air to limit the scattered precip chances. High pressure then skirts southeastward later Saturday with south- southwesterly flow increasing. Not looking as chilly overnight Saturday, but will continue to monitor trends for additional frost/freeze concerns. While still in the northwesterly flow for sunday low-level WAA and southerly winds are expected to warm southern WI back up toward normal (lower 60s) for the end of the weekend. However, accompanying this small warm up will also be increased shower and storm chances as a surface low develops and treks across central Canada later Sunday followed by another system early into the start of next week. Continue to see this active wave pattern with periodic upper-level shortwave troughs passages across the region with additional shower/storm chances through middle of next week.

Wagner

AVIATION

Issued 200 PM CDT Thu Apr 30 2026

Beginning to see the showers blossom over southeastern WI this afternoon along a lake breeze boundary. Expect the scattered light shower coverage to continue and spread across southern WI through the remainder of the afternoon and into the evening with the converging upper-level waves. Will see these sporadic showers persist into the evening before diminish tonight. While mostly seeing VFR conditions could see pockets of MVFR ceilings with any shower activity into the evening especially for the terminal closer to Lake Michigan. Otherwise, winds remain light and variable across the area into tonight with some clearing skies from west to east through daybreak. Friday will see similar conditions with lighter winds varying under predominantlyVFR conditions. Still could see another round of scattered showers develop and work their way through during the day.

Wagner

MARINE

Issued 200 PM CDT Thu Apr 30 2026

High pressure continues to sit over central Canada through the end of the week and will bring light and varying winds across Lake Michigan through Friday. High pressure begins to work its way southeastward tracking across Lake Michigan overnight Friday through the day Saturday. Will begin to see more southerly winds develop Saturday night and pick up into Sunday as the high pressure continues to track southward while low pressure treks across Ontario. This looks to drag a cold front week cold front across the lake later Sunday turning winds more westerly briefly before another low pressure develops right behind it for Monday. Expecting a stronger cold front to move across the Lake through the day Monday and turn winds north- northwesterly overnight into Tuesday.

Wagner

MKX WATCHES/WARNINGS/ADVISORIES

WI...Freeze Warning...WIZ046-WIZ047-WIZ056-WIZ057...midnight Friday to 8 AM Friday.

Frost Advisory...WIZ051-WIZ052-WIZ058-WIZ059-WIZ062-WIZ063- WIZ064-WIZ065-WIZ067-WIZ068-WIZ069-WIZ070...midnight Friday to 8 AM Friday.

LM...None.