NWS-Milwaukee/Sullivan Forecast Discussion

						FXUS63 KMKX 150830
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
330 AM CDT Tue Jul 15 2025

.KEY MESSAGES...

- Very warm and humid conditions today into Wednesday with
  maximum heat indices topping off in the lower 90s.

- Increased shower and thunderstorm chances through the day
  Wednesday (50-80%) with lower chances (20-40%) lingering into
  Thursday.

- Increasing potential (SPC risk 2 out of 5) to see stronger to
  even severe thunderstorms Wednesday afternoon/evening along
  with heavy rainfall across southern WI, but will depend on
  timing and placement of the cold frontal passage.

- Looking cooler and drier later Thursday into Friday with high
  temps in the 70s and lows in the 50s to around 60F.

- Unsettled weather returns for the weekend with 20-40% shower
  and storm chances each day.

&&

.SHORT TERM...
Issued 325 AM CDT Tue Jul 15 2025

Today and Tonight:

Today is looking very warm and more humid as south to
southwesterly flow advects in higher moisture. Dewpoints look
to creep into the upper 60s to low 70s this afternoon while
temps warm into the mid to upper 80s across southern WI. Will
also see feel like temps in the low to mid 90s this afternoon as
well. While expecting a predominantly dry forecast, some of the
00z CAMs such as the HRRR have hinted a few isolated pop-up
showers to develop later this evening in far southeastern WI
along a lake breeze as it may tap into the higher surface
moisture. However given lack of upper-level forcing and dry
model soundings throughout the column, will maintain no PoP
mentions at this time, but cannot be completely ruled out.

Otherwise, focus shifts to the trough progged to dig across the
Northern Plains overnight with a mid-level shortwave trough
ejecting out ahead of it. However, influence from this feature
looks to remain upstream across MN/northwest WI overnight before
moving in through the day Wednesday.

Wagner

&&

.LONG TERM...
Issued 325 AM CDT Tue Jul 15 2025

Wednesday:

A shortwave trough is expected to track into southwest WI
Wednesday afternoon. This shortwave should be in the form of an
MCV, remnant from anticipated convection over the Central Plains
this afternoon through tonight. A primed environment will be in
place over northern IL and southern WI Wed afternoon, with
dewpoints in the lower to mid 70s, temperatures in the upper
80s, and CAPE around 1000 j/kg with no cap. The shear will be
modest, around 20-25 kt, which would limit the sustainability
and organization of storms.

The expectation is that scattered thunderstorms will erupt over
northern IL and southern WI as the shortwave/remnant MCV tracks
into the region during peak daytime heating Wed afternoon. In
addition, the main cold front will be tracking across
northern/central WI and east-central MN during this time and
could support scattered storms along it. There is a threat for
damaging winds and 1 inch diameter hail with individual storms
or clusters of storms. The tornado risk is low. However, better
low level shear and would be along the lake breeze, so the
timing and intensity of the storms moving into southeast WI will
be important. If they arrive too late in the day, then the
instability will be lower and therefore the storms will be
weaker. There is still a lot of uncertainty in how these
potential storms will play out, so keep up with the forecast.

Late Wednesday night through Monday:

The main upper trough will slowly slide across Lake Superior
and northern WI Wed night, and the associated cold front will
gradually make its way down through central and southern WI
Thursday morning. There is a small chance for showers and a few
rumbles of thunder along the front late Wed night through late
Thu morning. High pressure will drift across WI Thursday
afternoon through Friday. Highs will only be in the 70s Thu and
Fri, and in the mid to upper 50s for most inland areas Thu
night.

Return flow around the high will start to increase the
dewpoints again Friday night into Saturday. A storm complex may
roll into southern WI on Sat. There is synoptic support from the
right entrance region of a weak upper jet and also the nose of
a low level jet, but this also looks like it could hinge upon
the prior days convection, so thus there is inherent
uncertainty. Depending on where a low level warm front sets up,
southern WI could see a couple rounds of thunderstorms early
next week.

Cronce

&&

.AVIATION...
Issued 325 AM CDT Tue Jul 15 2025

Some patchy fog across the Wisconsin river Valley early this
morning. Otherwise, VFR conditions prevail today with some
diurnally driven cumulus clouds (4-6kft) and southerly winds up
to around 10 knots. Warmer temps will once again contribute to
the development of a lake breeze, which could bring a brief
period of gusty, southeasterly winds to the eastern terminals
closer to the lakeshore between 18z-21z this afternoon. Light
winds and VFR conditions persist overnight into Wednesday
morning, but lower flight conditions along with shower/storm
chances increase through the day Wednesday.

Wagner

&&

.MARINE...
Issued 325 AM CDT Tue Jul 15 2025

Southerly winds continue to increase today into Wednesday as
high pressure over the northern Ohio River Valley slides east to
the Mid Atlantic States. Then looking at broad low pressure and
a cold front to track across southern WI and lower half of Lake
Michigan Wednesday through Wednesday night. Will see showers
and thunderstorms accompany this low pressure as it pushes
through the region. Cold front looks to push southeast of Lake
Michigan later Wednesday turning winds to the north behind it.
Northerly winds will persist into Thursday, but should gradually
weaken and turn more easterly Thursday night into Friday as
high pressure builds across the Upper Great Lakes.

Wagner

&&

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

$$

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