NWS-Milwaukee/Sullivan Forecast Discussion

						FXUS63 KMKX 200426
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
1126 PM CDT Sun Apr 19 2026

.KEY MESSAGES...

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

- Temps rise well above normal Tuesday through Thursday.

- Next chances (50-80%) for showers and thunderstorms Thursday
  night.

&&

.SHORT TERM...
Issued 1130 PM CDT Sun Apr 19 2026

Today through Tuesday night:

Lows this morning in the mid 20s to low 30s combined with calm
winds and clear skies will allow for widespread frost
development this morning, burning off shortly after sunrise.
High clouds are expected to move in by the afternoon hours, with
south- southwesterly winds increasing through the day as high
pressure exits to the southeast and low pressure propagates
through northern Manitoba. Gusts around 20 mph are expected,
with highs in the low 50s. Temperatures overnight are only
expected to dip into the low 40s, as southwesterly winds
continue.

A weak frontal boundary from the northern low will propagate
through southern Wisconsin Tuesday morning. A few showers are
possible across far southern Wisconsin as the front stalls, but
confidence is low with plenty of dry air in the 700 mb to
surface layer. Majority of this precipitation would evaporate
before reaching the ground. Expecting highs in the 70s as
southerly winds continue. A lake breeze may contribute to highs
in the mid 60s near Lake Michigan. Tuesday evening, the cold
front from the northern low will sweep through southern
Wisconsin from northeast to southwest. Expect lows in the mid
40s to upper 30s, with the lowest temperatures in the
Sheboygan/Fond du Lac areas.

MH

&&

.LONG TERM...
Issued 1130 PM CDT Sun Apr 19 2026

Wednesday through Sunday:

Second half of the week will be a warm one. Temps quickly
recover on Wednesday as the the upper-level ridge axis works its
way across the region. Given the high probabilities (+80%) from
the GEFS, ENS, and GEPS, expect daytime temps to warm back into
the 70s for Wednesday and even a potential for upper 70s and
maybe even crack 80F on Thursday. However, any easterly wind off
of Lake Michigan will keep things several degrees cooler along
the lakeshore to the Kettle Moraine, while further inland will
likely see the warmest temps. Overnight temps are also looking
milder for this time of year ranging from upper 40s to lower 60s
through the end of the week.

Accompanying this warm stretch will be another potential for
showers and thunderstorms as an upper-level trough swings across
the the Northern Plains and Upper Mississippi River Valley for
Thursday into Friday. The long range models continue a trend
pivoting the mid- level trough back northward as another trough
tries to phase with it. Given this trend, expect to see the
surface low follow suit and likely track across the Dakotas and
lift into Manitoba/northwestern Ontario later Thursday. While
southern WI will be on the warm side of this system with
instability building toward 1000J/kg, the better upper-level
forcing along with more favorable shear looks to remain to the
west-northwest close to the center of the low itself. Thus, the
more favorable setup for severe thunderstorm activity looks to
remain along and west of the Upper Mississippi River Valley at
this time. May see the decaying remnants of this activity work
its way into the western half of the area later Thursday. While
there is fairly consistent agreement on the long-range ensembles
as well as the ML severe probs for things to remain just
outside our area, we are still several days out and will be
monitoring for any eastward shift in the trends.

Friday is trending warmer, but the cold front associated with
the Thursday system is progged to gradually work its way across
southern WI through the day. This will bring cooler airmass to
the region for the weekend under mainly zonal upper-level flow.
However, not expecting as cold of temps as we saw with this past
weekend system, but generally looking at temps closer to
normal.

Wagner

&&

.AVIATION...
Issued 1130 PM CDT Sun Apr 19 2026

VFR conditions are expected throughout the TAF period, with a
few lingering clouds around 9000 ft clearing tonight, and then
high clouds around 15,000 to 25,000 ft moving in during the
afternoon hours today. A few clouds around 5000 ft are possible,
and these may produce a few sprinkles during the afternoon
hours in far southern Wisconsin.

Light and variable to calm winds through mid-morning, becoming
southwesterly and gusty around 15 to 20 kt by afternoon. Lake
Michigan terminals will see southerly to southeasterly winds,
still gusting between 15 and 20 kt. Winds will remain gusty but
become southerly into tonight, shifting back to southwesterly
into Tuesday morning.

MH

&&

.MARINE...
Issued 1130 PM CDT Sun Apr 19 2026

High pressure around 30.4 inches will bring light and variable
winds through this morning, with winds shifting to southerly
into this afternoon as high pressure exits into the Ohio Valley.
Low pressure around 29.5 inches will progress through northern
Manitoba into the Hudson Bay from this morning through Tuesday
morning, slowly shifting winds southwesterly and bringing gusts
around 30 kt tonight through Tuesday morning. In the northern
third of the lake, potential for a few gale force gusts exists.
Winds will shift to become northeasterly as a cold front sweeps
north to south through the lake Tuesday night into Wednesday
morning. High pressure of 30.1 inches builds into Ontario
Wednesday, bringing lighter and variable waves across the lake.
Low pressure then develops in the lee of the Rockies and deepens
to 29.1 inches, bringing gusty southeasterly winds to Lake
Michigan Thursday through Friday. Low pressure ejects into the
Canadian Prairies Friday night, bringing a cold front through
Lake Michigan and bringing a return to northwesterly winds.
Thunderstorms are possible along this front. Saturday will see
continued light northerly winds.

MH

&&

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

$$

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