963
FXUS63 KMKX 182017
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
317 PM CDT Fri Apr 18 2025

.KEY MESSAGES...

- Additional thunderstorm development is expected later this
  afternoon/evening. Large hail and damaging winds will be the
  primary hazards for any stronger storms.

- Quieter and cooler for Saturday.

- High chance (70-90%) of rain Sunday afternoon into early Monday

- Cooler Sunday and Monday, warming back to near or above normal
  temperatures by mid-week

&&

.SHORT TERM...
Issued 317 PM CDT Fri Apr 18 2025

Tonight through Saturday night:

A mid level shortwave is approaching from the northern plains
this afternoon. Showers/storms are already starting to fire
ahead of the cold front and ahead of this mid level shortwave
across far southern Wisconsin. The effective front is likely
across portions of southern Wisconsin where temperatures are in
the 70s and dewpoints are in the 60s. This will be the area to
watch convection as it starts to bubble up this afternoon.
Effective shear has been great across the state today with
values around 60 or greater. CAPE is still on the lower end, but
mid level lapse rates are great at 9c/km. Any low/mid level
capping will keep storms in check for a while. Once we break
through the capping the game is on for any stronger to severe
storms.

The cold front is likely to provide that forcing necessary to
have storms break the cap. South central and southeastern
Wisconsin are like to have the best potential for stronger to
severe storms given the set up. Strong wind and large hail will
be the main concerns. Mid level lapse rates are great for hail
support. For anything that does become surface based can`t rule
out the potential for a brief tornado, but the play for that
looks limited to roughly, Rock, Dane and Walworth where the
effect front has pulled far enough north to put them in a "warm"
sector. This window could close quickly as rain moves over this
area.

As the cold front moves through winds will shift to
northwesterly behind the front and dry air will begin to work in
on the backside. The last of the rain/storms are expected to
move out of southeastern Wisconsin by roughly 10 to 11 PM. High
pressure will begin to move in behind the this system tonight
into Saturday from the central Plains. This will keep conditions
dry throughout the day Saturday and into Saturday night.
Slightly cooler temperatures expected Saturday under the
northwest winds and weak caa. Highs will be in the lower to
upper 50s.

Patterson

&&

.LONG TERM...
Issued 317 PM CDT Fri Apr 18 2025

Sunday through Friday:

The next chance for rain/storms will be Sunday into Monday. Good
model consensus remains for a low pressure system to advect
northeast out of the Central Plains and move through southern
Wisconsin Sunday night into Monday. Warm air advection will be
good ahead of this system bringing temperatures into the upper
50s to low 60s prior to the start of the rain. WAA and theta e
advection will kick off the start of the rain/shower Sunday
afternoon. Then rain/storms will continue as the low moves in
with increased lift and instability give us a chance for chances
for thunderstorms. Once the rain moves in cooler air will
prevail.

Rain will linger through Monday morning as the shortwave and
low pressure system pull out to our east. Skies are expected to
remain cloudy behind the exiting low. Temperatures are still a
bit uncertain Monday due to the timing of the wind shift behind
the low and the CAA. Temperatures in the 40s to 50s are likely
but that 10 degree swing between could make for either a
pleasant or chilly day.

High pressure will slide into the area Monday night and quickly
exit to the east Tuesday morning as another weak short wave
approaches the region. As the shortwave, approaches the state
there will be a small chance (20-40%) for some showers and
storms.

Mostly dry conditions are expected Wednesday and Thursday, but
the pattern is open to shortwaves moving through during this
period, so low end precip chances will continue through mid-
week. Near to above normal temps are likely to continue for Wed
and Thu.

Patterson

&&

.AVIATION...
Issued 317 PM CDT Fri Apr 18 2025

Clearing skies across south central Wisconsin are expected to
persist through the rest of the late morning and into the early
afternoon. Terminals in far southern Wisconsin will continue to
see MVFR conditions with ceilings around 2-4 kft. Clouds are
being maintained along and north of the warm front to our south.
Additional chances for showers and thunderstorms are expected
this afternoon and evening. Storms are expected to form along
and ahead of an approaching cold front. There is a potential for
strong to severe storms. Hail and damaging winds will be the
primary concerns for any stronger storms. Lower ceilings and
visibilites will be possible with any thunderstorms. Dry
conditions and clearing skies are expected late tonight into
early Saturday. Partly cloudy skies and dry weather through
Saturday.

Southerly winds this morning are expected to become gusty again
this afternoon ahead of the approaching cold front. The cold
front will begin to move in from the northwest this afternoon
around 2 to 10 PM. Winds will shift to northwesterly behind the
front.

Patterson

&&

.MARINE...
Issued 317 PM CDT Fri Apr 18 2025

Breezy southerly winds persist as low pressure continues
northeastward from IA into WI and then crossing central portions
of the Lake this afternoon. Expect to see small craft
conditions across southern WI nearshore zones through this
afternoon/evening. A cold front will extend southwest from the
low crossing the southern half of lake later this afternoon and
evening. Modest south winds will veer northwest through this
evening (beginning with the northern lake, then the southern
half as the front passes). There are chances for thunderstorms
along with some hail and strong winds across southern half of
the Lake later today into tonight with the cold front. Modest
northwest winds continue behind the cold front overnight
followed by lighter north winds Saturday, as high pressure
builds into the Great Lakes region.

Patterson

&&

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

     Small Craft Advisory...LMZ643 until 4 PM Friday.

&&

$$

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