750
FXUS63 KMKX 190434
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
1134 PM CDT Mon May 18 2026

.KEY MESSAGES...

- Another round of showers and storms late this evening into the
  overnight hours. Just a very small potential for strong or
  severe storms.

- 30 percent chances for showers and isolated thunderstorms with
  the cold frontal passage on Tuesday. Severe thunderstorms are
  not expected.

- 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.

&&

.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 1134 PM CDT Mon May 18 2026

Numerous showers and scattered storms spreading west to east
across srn WI during the early morning hours. Areas of MVFR
Cigs and Vsbys may linger after the rain. More widespread MVFR
Cigs will then overspread srn WI just after sunrise and ahead of
the approaching cold front. Localized Cigs below 1 kft are
possible over south central WI. The Cigs will dissipate after
the cold frontal passage from mid to late afternoon. Gusty swly
winds to 30 kts are expected on Tue especially over ern WI. VFR
conditions for Tue nt.


Gehring

&&

.MARINE...
Issued 1134 PM CDT Mon May 18 2026

A Dense Fog Advisory is in effect tonight through Tuesday morning
for the north half of the lake as relatively mild and humid air
flows over the cold lake waters. Otherwise modest to breezy
southerly winds will develop tonight and last into early Tuesday
afternoon, then followed by the passage of a cold front. Winds
will shift to northwesterly with the cold frontal passage and
remain a bit breezy. Scattered thunderstorms can be expected over
the central and southern portion of the lake late tonight into
Tuesday. 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 from early morning Tuesday into the afternoon
for breezy southwest winds.

Gehring

&&

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

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

&&

$$

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