NWS-Milwaukee/Sullivan Forecast Discussion

						FXUS63 KMKX 231923
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
223 PM CDT Thu Apr 23 2026

.KEY MESSAGES...

- Periods of showers and storms (60-90 percent chance) expected
  late this evening through tonight. There is a Marginal Risk
  for severe storms mainly for damaging winds. Can't rule out
  isolated large hail or a brief tornado across southwestern
  Wisconsin.

- Showers are expected to redevelop on Friday especially over
  the ern half of WI. Isolated storms still possible.

- Dry weather with highs in the 60s this weekend; cooler by Lake
  Michigan due to light easterly winds.

- Widespread showers (80-90 percent chance) and isolated
  thunderstorms return late Sunday night through Monday night.
  Chances are fairly high for an inch of rainfall.


&&

.SHORT TERM...
Issued 223 PM CDT Thu Apr 23 2026

Tonight through Friday night:

Will be watching for convective development over ern IA later
this afternoon, where an outflow boundary resides, CAPE builds,
and increasing PVA primes the environment. At least scattered
storm development is likely and these would be the storms to
track newd into sw and south central WI as early as early
evening. Although effective shear will be a bit weak at 20 kts,
MLCAPE around 1000 J/KG and steep mid level lapse rates could
still support a severe storm.

Otherwise the main MCS, tied to the current storms over wrn IA,
will track into south central WI after 03Z-04Z. MUCAPE around
1000 J/KG may still be present over the region with swly 0-3km
shear at 30kts. With much of the wind shear located in the low
levels, bows and surges along the convective line will support
isold damaging winds. Mesovortex generation will be possible
with any bows or surges toward the north. Although mid level
lapse will initially be steep, a moistening troposphere with
PWATs rising to 1.3 inches will reduce the lapse rates by late
evening and aid in preventing greater coverage of severe winds.
Most CAMS then support the diminishing stage of the MCS for ern
WI as the outflow out runs the line, but still expect at least
60 percent chances for showers and isolated storms all the way
to Lake MI. Urban and small stream flooding will remain possible
over south central WI where 2-3 rounds of storms are possible.
Localized 2 inch rainfall amounts possible.

The models have sped up the cold front for Fri with higher
confidence in the front reaching Lake MI by 18Z, but there are
some indications of post frontal rain via mid level frontogenesis.
Thus will maintain fairly high PoPs of 50-70 percent, but lesser
west of Madison. Showers and isold storms will decrease from
west to east from the late morning into the early afternoon.
With impressive subsidence and drying afterward, sunshine
expected by early afternoon over south central WI and late
afternoon over ern WI. High temps in the middle to upper 60s are
forecast.
Areas of fog will continue over the lake into tonight and Friday
due to relatively mild and moist air flowing over the cold lake
surface. Modest south to southeast winds developing this afternoon
and lasting into Friday as a trough of low pressure and cold
front approaches from the Great Plains. However, breezy easterly
winds are expected over the northern tip of the lake this
afternoon into Friday, as the warm front will stall before
reaching said location.

The low will pull a cold front across Lake Michigan Friday afternoon
and evening, resulting in modest northwest to north winds.
Showers and thunderstorms are expected late tonight through
Friday, both ahead of and along the front. Severe weather is not
anticipated at this time.

Light north winds on Saturday will then become easterly Saturday
night and Sunday before increasing into Monday. 29.4 inch low
pressure is forecast to track northeastward from the central Great
Plains (Sunday night) near or over Lake Michigan (Monday night),
with gusty east to southeast winds ahead of its arrival and gusty
west winds behind it (into Tuesday). Not seeing widespread gale
potential with this system, though trends will be monitored.
Gehring

&&

.LONG TERM...
Issued 223 PM CDT Thu Apr 23 2026

Friday night through Thursday:

A weak high pressure area will then pass on Sat followed by
increasing sely winds and warm advection for Sunday ahead of
cyclogenesis over the central Great Plains. The low pressure
area and associated shortwave trough is then expected to lift
newd into WI Mon and Mon nt, with another round (70-90 percent)
of showers and storms. At this time, widespread rainfall totals
of an inch are reasonable. Relatively quiet weather will then
return Tue-Thu via wnwly flow aloft. Temps around normal are
forecast with slight chances for showers.

Gehring

&&

.AVIATION...
Issued 223 PM CDT Thu Apr 23 2026

Sct-bkn040 fair wx cumulus this afternoon along with gusty sly
winds. Widespread showers and scattered storms will then move
from west to east across srn WI late this evening into the
overnight. LLWS will form will then develop this evening and
linger into the overnight via a 200/45kt low level jet.

Areas of MVFR Cigs will develop over south central WI late this
evening into the early morning hours as showers and storms move
across that region. Widespread MVFR Cigs will then over spread
all of srn WI after 09Z and not dissipate until early Fri
afternoon. Showers and isold storms will continue Fri AM at
least over ern WI.

Gehring

&&

.MARINE...
Issued 223 PM CDT Thu Apr 23 2026

Areas of fog will continue over the lake into tonight and Friday
due to relatively mild and moist air flowing over the cold lake
surface. Modest south to southeast winds developing this afternoon
and lasting into Friday as a trough of low pressure and cold
front approaches from the Great Plains. However, breezy easterly
winds are expected over the northern tip of the lake this
afternoon into Friday, as the warm front will stall before
reaching said location.

The low will pull a cold front across Lake Michigan Friday afternoon
and evening, resulting in modest northwest to north winds.
Showers and thunderstorms are expected late tonight through
Friday, both ahead of and along the front. Severe weather is not
anticipated at this time.

Light north winds on Saturday will then become easterly Saturday
night and Sunday before increasing into Monday. 29.4 inch low
pressure is forecast to track northeastward from the central Great
Plains (Sunday night) near or over Lake Michigan (Monday night),
with gusty east to southeast winds ahead of its arrival and gusty
west winds behind it (into Tuesday). Not seeing widespread gale
potential with this system, though trends will be monitored.

A Small Craft Advisory remains in effect late this afternoon
into early Friday afternoon north of Port Washington for
building waves.

Gehring

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...None.
LM...Small Craft Advisory...LMZ643...4 PM Thursday to 1 PM Friday.

&&

$$

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