NWS-Milwaukee/Sullivan Forecast Discussion

						FXUS63 KMKX 231838
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
138 PM CDT Sat May 23 2026

.KEY MESSAGES...

- Expect a gradual warming trend through early next week with
  highs in the 80s by Memorial Day.

- 40-70% percent chances for showers late this afternoon over
  south central WI, slowly spreading east across S WI through
  the night. Isolated thunderstorms are possible.

&&

.SHORT TERM...
Issued 138 PM CDT Sat May 23 2026

This afternoon into Sunday Night:

The main focus through tomorrow is on the chances for rain
showers/isolated thunderstorms this afternoon into tonight
followed by some borderline fire weather conditions on Sunday.

For this afternoon into tonight, watching a narrow corridor of
convergence/forcing/moisture that will propagate eastward and
bring a 2-4 hour window of rain showers along with it across
southern Wisconsin. Meso guidance has been fairly consistent
with the timing and environment as this comes through SW WI
around 21-02z and through SE WI between 2-8z. SBCAPE of about
300-500 J/kg develops along this narrow corridor with the
RAP/NAM/GFS soundings all showing this unstable layer being
between 850-650mb or 0 to +10C. Mid level temps are fairly warm,
so am doubtful that we'll see much in the way of lightning
activity with this despite the instability as any ice formation
would be minimal. Regardless, will be watching the window as
this moves through into tonight.

Depending on how fast this band moves through, there could be
some patchy radiation fog that develops tomorrow morning as
winds will be light to calm, dew point spread minimal and
possibly some fresh rain from these showers moving through. IF
the fog does form, it will quickly dissipate by mid morning due
to the warmer and drier air advecting in on the northern
periphery of the surface ridge. Going through the rest of
Sunday, skies should be clear/sunny with deep mixing likely by
the late morning hours. Winds will increase to potentially gust
up to around 20kts when peak mixing occurs which should also
drop the dew points/RHs a bit. With temperatures getting into
the 70s, will have to watch the trends for mixing and if we have
some borderline fire weather concerns. Fuels don't appear to be
there/an issue though with green up complete.

Halbach

&&

.LONG TERM...
Issued 138 PM CDT Sat May 23 2026

Monday through Saturday:

A warmer pattern looks to setup for much of next week as the
low/mid level flow becomes more southwesterly with 850mb temps
getting to around +15C by Monday and staying there through much
of the week. There's some uncertainty going into the later part
of next week as the 23.12z GFS and GEM retrogrades an upper
level low back south across New England which puts the Great
Lakes region into the backside, NE cold air advection area of
the low. However, the 23.00z Euro doesn't show this occurring
and keeps us in the warmth.

Not much in the way for any rain expected over this period as
much of the long term guidance shows surface ridging over much
of the Great Lakes region. IF the 23.12z GFS scenario pans out,
there could be a chance when the cold front/CAA kicks in on
Tuesday night/Wednesday.

Halbach

&&

.AVIATION...
Issued 138 PM CDT Sat May 23 2026

MVFR to IFR ceilings along Lake Michigan have dissipated with
VFR conditions expected to persist through the rest of the
afternoon. The focus then goes to a band of clouds and rain
showers that are expected to move through southern Wisconsin
later this afternoon into tonight. Isolated thunderstorms will
be possible, but not likely, to occur. Ceilings should stay at
about 3500ft as these showers come through, but can't rule out a
brief drop to below 3kft. After the rain showers come through,
skies are eventually expected to clear out. If they clear out
more quickly, there could be some patchy fog that develops as
winds will be light/calm and some fresh rain may have just
occurred. Some brief visibility drops between 9-13z will be
possible if this occurs. Going into Sunday, winds are expected
to increase and become more gusty (~16 to 20kts) toward late
morning.  VFR conditions expected through the day Sunday.


Halbach

&&

.MARINE...
Issued 138 PM CDT Sat May 23 2026

Main focus over Lake Michigan is with any potential fog that
develops today into tonight after some rain moves through.
Otherwise, the tighter pressure gradient looks to be more over
the northern half of the Lake going into early next week, but
nothing that is strong enough to produce too high of winds.

Halbach

&&

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

$$

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