NWS-Milwaukee/Sullivan Forecast Discussion

						FXUS63 KMKX 192347
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
647 PM CDT Sun Apr 19 2026

.KEY MESSAGES...

- Frost is expected overnight into early Monday morning, with
  low temperatures in the middle to upper 20s. Those with
  sensitive plants should cover them tonight.

- Temperatures rise well above normal Tuesday through Thursday.

- Next chances (40 to 60 percent) for showers and thunderstorms
  Thursday night.

&&

.UPDATE...
Issued 647 PM CDT Sun Apr 19 2026

Forecast remains on track. Light sprinkles will exit offshore
into Lake Michigan by sunset, with temperatures rapidly falling
into the low 30s to mid 20s overnight. Frost is expected, so any
sensitive plans should be covered or brought indoors.

MH

&&

.SHORT TERM...
Issued 159 PM CDT Sun Apr 19 2026

Tonight and Monday:

Scattered sprinkles/flurries or light rain/snow showers will
continue to shift southeast through the area until early this
evening. No snow accumulations are expected. They are being
driven by continued differential CVA from a passing 500 mb
vorticity maximum, as well as fairly robust low to mid-level
frontogenesis response. This activity should linger through peak
heating this afternoon, before weakening by early evening.

Otherwise, scattered to broken clouds should linger until early
this evening. Gusty northwest winds into early evening should
also weaken tonight, as high pressure moves southeast into the
region. Skies should gradually clear out this evening, with
mostly clear skies overnight into early Monday morning.

The light winds and clearing skies should allow for lows to drop
into the middle to upper 20s over most of the area. This should
allow for frost to develop. Those with sensitive plants should
cover them tonight.

Dry conditions are expected Monday, as the high shifts to the
southeast of the area. Some diurnal stratocumulus clouds or
mid-level clouds may develop and move through the area. Some
lake effect clouds may also shift southwest toward the lakeshore
areas in the afternoon.

Light south southwest winds are expected inland, with a
southeast lake breeze in the afternoon near Lake Michigan. Highs
should rise into the lower to middle 50s inland, with weak warm
air advection, and 40s closer to the lake.

Wood

&&

.LONG TERM...
Issued 159 PM CDT Sun Apr 19 2026

Monday night through Sunday:

500 mb cluster analysis continues to show an anomalous ridge
axis developing over the Great Lakes region Tuesday into
Thursday, before an anomalous trough shifts east into the region
by the weekend and elongates over a good portion of the north
central part of the country.

This setup should allow for generally south to southwest winds
and warm air advection to develop and continue Tuesday into
Thursday across the area, which should result in a warming trend
toward well above normal temperatures Tuesday into Thursday.

One caveat will be a backdoor cold front that shifts south
southwest across Lake Michigan later Tuesday afternoon and
evening. This will bring a sharp drop in temperatures near the
lake later on Tuesday, then across the rest of the area into
Tuesday evening. Onshore winds Wednesday should keep lakeshore
areas much cooler than the lower to middle 70s well inland.
Thursday should bring south southwest winds over most of the
area, with highs well into the 70s. Lakeshore areas may see
south southeast winds and some cooler temperatures there.

Ensemble means suggest the cold front should move east through
the area Thursday night and exit by midday Friday. This will
bring the next chances (50 to 80 percent) for showers and
thunderstorms. Will have to watch for some stronger storm
potential, though the frontal timing is not ideal and the best
chances for this may be southwest of Wisconsin. The front looks
fairly progressive, so may have a relatively low heavy rain
risk.

Kept the rest of the forecast as is for now, which looks to be
somewhat cooler, but still mild, with small (around 20 percent)
chances for showers at times.

Wood

&&

.AVIATION...
Issued 647 PM CDT Sun Apr 19 2026

Northwesterly winds continue in the majority of southerner
Wisconsin, with a lake breeze encroaching inland for the next
hour near SBM and RAC. After sunset, expect winds to shift
northwesterly and diminish, with calm winds late tonight through
Monday morning. Winds will then become southwesterly around 10
kt Monday morning, with a few gusts around 20 kt near Lake
Michigan. A lake breeze is expected Monday afternoon, shifting
winds to southeasterly near Lake Michigan. Winds will remain
southeasterly into Monday night, with the lake breeze exiting
back offshore around sunset. VFR conditions are expected
throughout the TAF timeframe.

MH

&&

.MARINE...
Issued 159 PM CDT Sun Apr 19 2026

A few northwest gusts to 25 knots may occur into early evening
for the nearshore waters of Lake Michigan, but not frequent
enough for a Small Craft Advisory.

High pressure around 30.4 inches is expected to shift southeast
across the region tonight into Monday morning, then shift
southeast in the afternoon. Gusty north to northwest winds are
expected into early evening, before weakening tonight into
Monday.

Increasing south winds are expected later Monday afternoon into
Monday night, as the high moves further southeast of the region.
A few gales may occur Monday night into early Tuesday morning,
particularly over the northern third of the lake.

Winds and waves may reach Small Craft Advisory levels at times
later Monday into early Tuesday, mainly north of Port
Washington.

A backdoor cold front should then move southward across Lake
Michigan Tuesday afternoon and evening, shifting winds to the
northeast behind it. High pressure around 30.4 inches to the
northeast of the region Wednesday should bring lighter winds to
the area.

Winds should become southeast to south and increase later in
the week, as strong low pressure around 29.2 inches develops in
the northern Plains. Winds and waves may reach Small Craft
Advisory levels at times in the nearshore waters during this
period.

Wood

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...None.
LM...None.
&&

$$

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