NWS-Milwaukee/Sullivan Forecast Discussion

						FXUS63 KMKX 192025
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
325 PM CDT Tue May 19 2026

.KEY MESSAGES...

- Gusty northwest winds in the wake of a cold front will
  diminish this evening.

- Easterly winds will keep lakeshore temperatures cooler than
  inland areas Wednesday through Friday. Expect a gradual
  warming trend Saturday through Memorial Day.

- Rain chances return Friday afternoon and night (40-60%), with
  much smaller chances the rest of the holiday weekend.

&&

.SHORT TERM...
Issued 325 PM CDT Tue May 19 2026

Tonight through Wednesday Night:

Gusty west-northwest winds in the wake of the surface cold
front will gradually diminish through late evening as an
inversion sets up. Cloud cover is more uncertain, but there
should be a thinning/clearing trend from west to east
overnight. The upper wave will swing across WI much later than
the surface front, so temps will remain on the milder side
during the overnight period, ranging from the upper 40s
southeast to the lower 40s toward central WI.

By 12Z/7AM Wed, the mid level trough and 850mb front will be
stalled over central WI. Meanwhile, a shortwave tracking across
the Plains will push into southern WI by midday. The
interaction of the 850mb front sliding south and the incoming
shortwave will help colder air rush down the lakeshore quicker
than inland (back door cold front) during Wed morning. This
should also bring a period of low clouds to the lakeshore and
slightly higher but still widespread clouds to inland areas.
Temps will remain cooler near the lake, with highs ranging from
the mid 50s lakeshore to the lower/mid 60s well inland.

Despite surface high pressure sitting over the Upper Great
Lakes, the mid level shortwave and right entrance region of the
upper jet should keep at least mid level clouds around. Without
the clearing and with a persistent light easterly breeze, our
frost potential is very low. The forecast low temps are between
39 and 42. This is slightly up from the previous forecast and
nearly lined up with the 50th percentile of model solutions.


Cronce

&&

.LONG TERM...
Issued 325 PM CDT Tue May 19 2026

Thursday through Tuesday:

The upper level pattern will be very similar to Wed on Thursday.
The mid level clouds may be even thicker. A steady easterly
breeze will keep lakeshore temps cooler than inland (similar
temps as Wed). Thursday night lows will be in the lower to mid
40s. The surface east winds will remain steady through Friday,
and this may help to hold off the rain. Models are trending
later with the arrival of our next chance for precip.

An upper trough progressing through the Northern Plains Thursday
night into Friday will swing into MN Fri evening. Meanwhile, a
weak low crossing MO and IL will slide into Lower Michigan.
Southern WI will be in the middle of those features, but weak
warm air advection and the synoptic forcing could be enough for
scattered light showers. The thunder threat is looking lower
now due to the probable timing into the evening/overnight. There
is no severe threat. The ECMWF has a wetter look to the Fri
nt/Sat period than the GFS at this time. We will keep a close
eye on this for the holiday weekend.

The upper trough will be crossing WI on Sunday and this will
bring a chance for showers of the scattered, pop-up variety. If
the low level lapse rates are steep enough, a few rumbles of
thunder look possible Sunday afternoon. This would not be an
all-day wash-out. Monday weather looks quiet right now, as we
will be between systems.

There will be a warming trend with the temps through the
Memorial Day weekend, with highs around 70 Sat, 75 Sun, and 80
Mon.

Cronce

&&

.AVIATION...
Issued 325 PM CDT Tue May 19 2026

Expect MVFR ceilings and gusty northwest winds behind a cold
front that is currently crossing southeast WI (now near
Milwaukee). Ceilings should lift to VFR late this afternoon and
then disperse tonight as skies gradually clear as high pressure
works into the region.

Clouds below 5000 ft should be present on Wednesday, especially
closer to Lake Michigan where a period of MVFR ceilings are
expected as the northeast winds develop in the morning. The
northeast winds will expand inland through early afternoon.

Cronce

&&

.MARINE...
Issued 325 PM CDT Tue May 19 2026

Gusty westerly winds are developing in the wake of a cold front
this afternoon. Gusts up to 30 kt will be possible right behind
the front and then winds will gradually diminish overnight. High
pressure will then move into the northern Great Lakes on
Wednesday. Modest northeast winds are expected Wednesday
afternoon through Thursday, especially over the south half.
Winds will remain easterly through Saturday as strong high
pressure tracks across Ontario and Quebec and a weak low
pressure trough sets up in the Plains.

The Small Craft Advisory for the nearshore was extended until 7
PM CDT this evening due to gusty west-northwest winds. Northeast
winds will develop Wednesday morning and persist through
Saturday. This will build high waves in the nearshore areas by
Wednesday afternoon. Another small craft advy will be needed.

Cronce

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...None.
LM...Small Craft Advisory...LMZ643-LMZ644-LMZ645-LMZ646 until 7
PM Tuesday.

&&

$$

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