NWS-Milwaukee/Sullivan Forecast Discussion

						FXUS63 KMKX 191656 AAA
AFDMKX

Area Forecast Discussion...UPDATED
National Weather Service Milwaukee/Sullivan WI
1156 AM CDT Tue May 19 2026

.KEY MESSAGES...

- Diminishing chance for showers with the cold frontal passage
  today.

- Cool and drier weather then returns for midweek.

- Rain chances return Friday into Friday night(40-60%),
  followed by a gradual warming trend Saturday into early next
  week.

&&

.UPDATE...
Issued 1156 AM CDT Tue May 19 2026

The cold front is apparent on radar and is trekking through
south central WI right now. It is almost to Madison. Sprinkles
or a light shower are possible along the front. Then expect a
wind shift to the west-northwest behind the front, with gusts up
to 25 mph (not a lot different than the gusts going on right
now). There are plenty of clouds upstream due to the diurnal
influence, so expect these to thin out overnight. Lows will be
in the lower-mid 40s tonight.

Cronce

&&

.SHORT TERM...
Issued 1134 PM CDT Mon May 18 2026

Tonight through Thursday night:

The decaying MCS is now moving into sw WI and will continue to
encounter much greater MLCIN and high LFCs. However, still
expect fairly widespread showers and sct storms to move across
all of srn WI during the early morning hours as a sswly low
level jet of 40 kts increases warm, moist advection and boosts
elevated CAPE to 1000-2000 J/KG. Wind gusts and small hail will
be the main concerns.

A wave of low pressure along the stationary front from central
IA to ern MN will track newd to near Lake Superior by 12Z Tue.
The low will then track ewd into Quebec during the day with its
trailing cold front moving across srn WI Tue AM into the early
afternoon. Moist low levels and marginal instability could
result in a broken line of showers and isold storms along the
front but no severe wx is anticipated.

Nwly winds and cold advection will continue into Tue nt with low
temps falling into the lower to middle 40s. High pressure will
then move from MN to the nrn Great Lakes on Wed and remain there
into Thu. Nely sfc winds and a relatively cool air mass will
reside over srn WI with high temps in the 50s over ern WI and
lower 60s over south central WI. A return of warm advection will
bring 20 percent chances for showers west of Madison Thu nt.

Gehring

&&

.LONG TERM...
Issued 1134 PM CDT Mon May 18 2026

Friday through Monday:

Low pressure ejects from the Southern Plains on Friday, with
continued model discrepancies as to its progression. Canadian and
Euro indicate a more southerly track of a single low pressure
system bringing widespread rain and storms to southern Wisconsin
throughout the day along the northern side of the low, while the
GFS prefers a split pattern with one portion of the energy
progressing through the lower Mississippi Valley and the other
following the jet stream into Minnesota and brings a warm front
with rain and storms into southern Wisconsin. Regardless of
solution, probabilities of seeing rainfall have increased, so kept
likely PoPs (50-65%) in the forecast for Friday afternoon into
Friday night. Models also are inclined to agree that precipitation
will taper off into Saturday as the warm front lifts north or the
low pressure system exits to the east. Generally unsettled weather
looks to develop Sunday through Tuesday as broad 500 mb troughing
develops across the Upper Midwest, bringing multiple shortwaves
through the region. As the upper level troughing develops, high
pressure building in the Plains will bring increasing temperatures
through the weekend into early next week. Monday and Tuesday
temperatures could return to the mid-80s. However, weak, generally
southeasterly winds will allow for Lake Michigan influence on
temperatures in the easternmost counties.

MH

&&

.AVIATION...
Issued 1156 AM CDT Tue May 19 2026

Expect MVFR ceilings ahead of and behind a cold front that is
currently crossing southern WI (now near Madison). Breezy
southwest winds will become west to northwest winds behind the
front this afternoon and evening. 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. Wind should be out of the northeast
near the lake and then the northeast winds will expand inland
through early afternoon.

Cronce

&&

.MARINE...
Issued 1156 AM CDT Mon May 18 2026

The Marine Dense Fog Advisory for the north half of Lake
Michigan was extended through mid afternoon due to relatively
mild and humid air flowing over the cold lake waters. Fog will
linger until the cold front moves through.Otherwise modest to
breezy southerly winds will persist ahead of the front, then
shift to the west-northwest and remain breezy through most of
tonight. High pressure around 30.4 inches will then move into
the northern Great Lakes for Wednesday afternoon into Thursday.
Light to modest north to northeast winds can be expected.

A Small Craft Advisory is in effect from Sheboygan to
Winthrop Harbor through late afternoon for breezy southwest to
west winds.

Cronce

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...None.
LM...Small Craft Advisory...LMZ643-LMZ644-LMZ645-LMZ646 until 4 PM
     Tuesday.

     Dense Fog Advisory...LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565-
     LMZ567-LMZ868 until 3 PM Tuesday.

&&

$$

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