165
FXUS63 KMKX 161546
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
1046 AM CDT Wed Apr 16 2025

.KEY MESSAGES...

- Next chances for showers and and storms across southern
  Wisconsin is Thursday afternoon through Friday (50-80%). There
  are low probabilities for severe storms for this period.

- 70 degree temperatures are possible on Friday.

&&

.UPDATE...
Issued 1045 AM CDT Wed Apr 16 2025

Quiet conditions expected today with high pressure overhead. The
light winds and warming temperatures will likely trigger a lake
breeze this afternoon but otherwise it is expected to remain
quiet through tonight.

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.

By Thursday afternoon we will be monitoring development in Iowa
and southern MN for storms along a front with some severe
storms likely to our west. A weak shortwave aloft will move
across southern WI in the afternoon with an increasing low
level jet expected 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. The afternoon may remain fairly dry during the day
despite some periods of forcing and moisture capable of bringing
some showers. The disjunction of the upper level and lower
level moisture and forcing give the region potential to see some
showers but currently lend itself toward a drier forecast
though likely being cloudy much of the day.

Into Thursday evening/night we will be watch 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 and strong to
severe storms will decrease as it gets later as we lose our
instability to some degree but models do show elevated CAPE
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 with the decent elevated
instability 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.

Kuroski

&&

.SHORT TERM...
Issued 353 AM CDT Wed Apr 16 2025

Today through Friday night:

Stratus clouds over east central WI will slide down the lake for
the next few hours before dissipating. Otherwise, the north to
south sfc ridge over WI will slowly shift across the state
today. A lake breeze will develop by late morning and move
inland with high temps only in the 40s near the lake and 50s
inland. For tnt, scattered to broken mid level clouds are
expected via mid level warm, moist advection that is associated
with an upper ridge building in from the Great Plains.

Low to mid level warm, moist advection and sly winds will
increase on Thu as a sfc trough moves into srn MN and wrn IA
from the Great Plains. Aloft, a weak shortwave trough within
swly flow will move across srn WI in the afternoon with an
increasing low level jet expected. Elevated CAPE will remain
very marginal, but showers are likely with 20-30 percent chances
for thunder. This will continue into Thu night while deeper
convection over srn MN could clip the counties toward central
WI late. Elevated CAPE will remain very limited and severe
storms are not anticipated.

Finally for Fri, gradually weakening low pressure will move from
ern IA to nrn lower MI through the day with its cold frontal
passage in srn WI during the afternoon. Upper dynamics are
lacking with only a longwave upper trough located from south
central Canada into the nrn Great Plains. There is a plume of
warm air aloft via the elevated mixed layer that advected into
the region from the sw. The GFS and ECMWF do eventually depict
convective initiation but mostly to the east of WI. Will still
maintain 50 percent chances for rain for any lingering rain from
Thu nt and/or new development Fri afternoon. If storms do
initiate Fri afternoon, strong deep and unidirectional shear
will combine with MLCAPE around 1500 J/KG to bring some
potential for severe storms, albeit limited in coverage.

Gehring

&&

.LONG TERM...
Issued 353 AM CDT Wed Apr 16 2025

Saturday through Tuesday:

Relative high pressure should build behind the exiting low
pressure system on Saturday and weak CAA on northwest winds will
drop temperatures back into the 50s.

Quite a bit of spread in solutions are then in store for Sunday as
the ECMWF, GFS, and Canadian all deepen a low pressure system to
varying degrees over the upper Midwest on Sunday ahead of a
digging trough. The GFS features a broader, low amplitude 500 mb
trough which leads to a weaker surface low that travels on a
flatter west to east path across the Corn Belt, while ECMWF and
Canadian models favor a more pronounced upper trough and much
deeper sfc low that moves north-northeast over Wisconsin. Even
with said spread, the NBM brings rain/thunder chances into
southern WI Sunday afternoon (favoring the ECMWF and Canadian
solutions) with precipitation chances increasing to 50 to 60%
overnight into Monday. NBM precip chances then linger through
much of Monday, although these chances may be overblown as
models show this system being fairly progressive off to the
east. Warm advection then takes hold toward the end of the
extended period with warming temperatures.

CMiller

&&

.AVIATION...
Issued 1045 AM CDT Wed Apr 16 2025

Quiet conditions expected today with high pressure overhead. The
light winds and warming temperatures will likely trigger a lake
breeze this afternoon breezier southeast winds with and behind
the boundary, primarily affecting areas closer to the lake early
this afternoon and gradually sliding west through the afternoon.
CIGS and VSBYS will remain VFR through tonight. Into Thursday
breezier southeast winds are expected with some showers and
maybe a weak storms 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 353 AM CDT Wed Apr 16 2025

Northerly winds will continue to weaken this morning, then
becoming light and variable for this afternoon and evening as high
pressure around 30.2 inches over Wisconsin moves across the lake.

Breezy south to southeast winds will then develop for Thursday and
Thursday night as low pressure moves across the central Great
Plains into Iowa. Modest southerly winds on Friday will then
shift northwesterly late Friday afternoon or evening with the
passage of a cold front.

Gehring

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...None.
LM...None.
&&

$$

Visit us at weather.gov/milwaukee

Follow us on Facebook, Twitter, and YouTube at:
www.facebook.com/NWSMilwaukee
www.twitter.com/NWSMilwaukee
www.youtube.com/NWSMilwaukee