403
FXUS63 KMKX 161950
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
250 PM CDT Wed Apr 16 2025

.KEY MESSAGES...

- Next chances for showers and and storms across southern
  Wisconsin is Thursday afternoon through Friday (40-70%).
  There are low probabilities for severe storms for this period.

- Warming up over the next few days with 70 degree temperatures
  likely Friday.

- Another system will come through Sunday/Sunday night bringing
  rain to southern WI.


&&

.SHORT TERM...
Issued 230 PM CDT Wed Apr 16 2025

Tonight through Thursday Night:

Into Thursday we will be watching the high slide out east though
remaining over the Great Lakes region as lower pressure over the
Central Plains pushes east and impinges on the high to the east.
This will create an increased pressure gradient across southern
WI with breezy southeast winds likely. While temperatures will
warm up quite a bit across much of the CWA into the low to mid
60s the areas near the lake and especially toward east-central
WI will be much cooler due to the lake. In addition a lake
breeze may develop and bring cooler conditions to the nearshore
areas by the early afternoon.

Thursday afternoon, a weak shortwave aloft will move across
southern WI with an increasing low level jet expected through
the late afternoon and into the evening. Elevated CAPE will
remain very marginal during the afternoon with only a few
rumbles of thunder possible and primarily further west based on
current models (though this wave of elevated CAPE will be
pushing northeast). The afternoon may remain fairly dry (10-25%
PoPs) during the day despite a layer of midlevel moisture and
WAA capable of bringing some showers. The disjunction of the
upper and lower level moisture and forcing give the region
potential to see some showers but currently lend itself toward a
drier forecast, though likely (80%) being cloudy much of the
day. Continuing into early Thursday evening there will be an
increasing chance (30-40%) for some showers and storms
developing over the CWA in association with that midlevel
moisture and WAA but has the increased influence/forcing from
the LLJ. The primary risk with this would be small hail given
continued weak elevated instability (at most 750 J/kg), thus
severe storms would not be expected. The potential for
development will be focused more toward eastern and east-central
WI

Into later Thursday evening/night we will continue watching as
storms push in from our west but there remains quite a bit of
uncertainty among models, especially the short term model
guidance (CAMs) regarding timing. Storms would largely be
expected to push in sometime during the mid to late evening and
push out by the early morning hours. Certainly the risks for
strong to severe storms will decrease as it gets later as we
lose our instability to some degree but models do show elevated
CAPE (~1000 J/kg) through the overnight period. The risks into
the evening and overnight period are primarily limited to hail
given the elevated nature of storms by that time but could
yield some borderline severe hail. However, the most likely
outcome is pea to nickel sized hail with a few storms possibly
bringing a few larger hailstones.

Friday:

The potential for storms Friday rests almost entirely on the
front; how quickly it pushes through, if the front can overcome
the strong capping due to the strong EML and (assuming
initiation) the timing of initiation along the front. Much of
the short term CAM guidance suggests very little in the way of
activity through the afternoon as the front is expected to push
through during the early to late afternoon hours. CAM guidance
does however support the idea of the reduction in CIN across the
area as the front slides east. If the erosion of the EML occurs
with the frontal passage then we could see convection initiation
somewhere in the southeast portions of the CWA. If we can manage
some convection in the CWA Friday afternoon all hazards will be
possible given peak instability from 1500-2000 J/kg and deep
layer shear around 50 to 60 kts and decent low level
shear/helicity. The front is very likely to push entirely
through the area by the late afternoon with precip/storms
chances completely dropping off behind the front.

Kuroski

&&

.LONG TERM...
Issued 230 PM CDT Wed Apr 16 2025

Friday Night through Wednesday:

Some showers may linger Friday evening, until cold air advection
on northwest winds brings drier air into the area by later Friday
night. There should be a brief dry period into Saturday and
Saturday evening, as weak high pressure passes by to the north of
the area.

Deterministic models and ensembles are showing low pressure moving
northeast through the region sometime in the Sunday into Sunday
night period. Lots of moisture and upward vertical motion with
this system as well, with a negatively tilted 500 mb shortwave
trough shifting through the region. Continued with likely PoPs
(55 to 70 percent) for this period in the forecast. Kept small
thunder chances going (around 20 percent) as well for Sunday
evening. Ensembles suggest a good probability (greater than 50
percent chance) for at least 0.50 inches of precipitation with
this system, so it looks to bring a nice wetting rainfall to the
area.

Ensembles suggest that mild temperatures into the 60s away from
Lake Michigan should move in by Tuesday, and possibly linger
through the rest of next week. There may be on and off chances for
showers as well during this period, as the region remains in
generally zonal 500 mb flow.

Wood

&&

.AVIATION...
Issued 230 PM CDT Wed Apr 16 2025

Quiet conditions expected tonight with high pressure overhead.
CIGS and VSBYS will remain VFR through tonight. Into Thursday
breezier southeast winds are expected with some showers and
maybe a weak storm across western WI with most of the rest of
the area largely expected to remain dry though a light shower
cannot be ruled out. VSBYS could be reduced in showers or a weak
thunderstorm but would otherwise be expected to remain
unimpacted through the day Thursday. MVFR CIGS are expected to
push into southwest WI by the mid to late morning and envelope
the area by the mid afternoon hours as the system from the west
pushes toward the region.

Kuroski

&&

.MARINE...
Issued 230 PM CDT Wed Apr 16 2025

Winds will turn southeasterly this evening remaining light and
variable as high pressure slides east of the lake tonight.

Southeast winds will become breezy for Thursday and Thursday
night as low pressure moves across the central Great Plains into
Iowa. Gales will be possible across east-central portions of the
lake Thursday afternoon through the evening but look more
unlikely given the strong inversion layer. Modest southerly
winds on Friday will then shift northwesterly late Friday
afternoon or evening with the passage of a cold front. A Small
Craft Advisory has been issued for high winds and waves from
Thursday morning into Friday. Storms possible over the southern
lake Thursday late afternoon through Friday.

Kuroski

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...None.
LM...Small Craft Advisory...LMZ644-LMZ645-LMZ646...7 AM Thursday to
     7 AM Friday.

     Small Craft Advisory...LMZ643...7 AM Thursday to 4 PM Friday.

&&

$$

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