NWS-Milwaukee/Sullivan Forecast Discussion

						FXUS63 KMKX 301905
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
205 PM CDT Thu Apr 30 2026

.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.
&&

$$

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