350
FXUS63 KMKX 171724
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
1224 PM CDT Tue Jun 17 2025

.KEY MESSAGES...

- Scattered thunderstorms late this afternoon and early evening
  mainly along and south of a line from Madison to Milwaukee
  along a weak stationary front. Additional showers and
  scattered storms will then develop over all of S WI late tnt.

- Widespread showers and scattered storms on Wednesday with
  heavy rainfall at times especially for southeast WI.

- Very warm and humid conditions are looking more likely for the
  weekend into early next week.

&&

.UPDATE...
Issued 1224 PM CDT Tue Jun 17 2025

A weakening cold front north of Madison and Milwaukee will stall
near the IL border by early evening. MLCAPE will rise to
1500-2000 J/KG with little to no capping, while the CAMs do
initiate scattered convectiion along the the front. Wind shear
is weak, but a few strong pulse storms will be possible given
the respectable CAPE values and some mid to upper level dry air
and 6.5-7.0 C/KM lapse rates contributing to downburst
potential.

Late this evening into the overnight, showers and storms will
continue to develop from south to north across S WI as a mid
level shortwave trough currently over ern NE and sw IA drifts
newd into se WI, while a more organized shortwave trough moves
into IA and nrn MO by 12Z Wed. The storms will become more
elevated with only marginal CAPE present for this activity.
Storm motion will be swly around 15 kts late this afternoon and
evening within PWs of 1.5 inches so heavy rainfall and possible
urban and small stream flooding.

Gehring

&&

.SHORT TERM...
Issued 300 AM CDT Tue Jun 17 2025

Today and Tonight:

A cold front based from the low pressure system moving across
the northern Great lakes will continue through the region early
this morning but will for the most part remain dry outside of a
few isolated showers. This front will layover and become
stationary and east-west oriented as it becomes the warm front
for the developing system over the Central Plains that will be
push east toward the area today.

There still remains quite a bit of uncertainty on where this
boundary will end up as it will be the focus for convection
later today. In addition to the front there will some upper
level support from a shortwave as well with some WAA to the low
to midlevels on the nose of a weak LLJ. In addition moisture is
not really expected to be an issue so this largely comes down to
location of where things get going and models still show quite
a bit of differences. Most of the CAMs show convection across at
least parts of the area but the RRFS and HRRR keep most of the
potential south of the area. We will need to closely monitor
where the front sets up later today to determine where the best
chances for storms will be. In either case while instability may
be plentiful the deep layer shear will be weak and thus storms
may not organize all that well. Depending on where the boundary
sets up we could see upwards of 2000 J/kg of MUCAPE and thus we
couldn`t rule out stronger storms but that shear environment
would not likely sustain them for very long. Large hail would be
the primary concern with storms with a chance for stronger gusts
as well, especially with any degree of organization.

Best chances for storms will be during the late afternoon
through the mid evening hours with quieting conditions overnight
ahead of the approaching low into Wednesday morning.

It is worth mentioning that temperatures will likely reach the
mid 80s with temperatures possible reaching the 90s east of the
Kettle Moraine in southeast WI with help from downsloping with
west to southwest winds. In addition we could see dewpoints in
some spots get near 70 making for some humid conditions. A lake
breeze circulation may also form later in the day despite modest
west winds as the temperature differences will be quite stark
perhaps strengthening the circulation more than models currently
project.

Kuroski

&&

.LONG TERM...
Issued 300 AM CDT Tue Jun 17 2025

Wednesday through Monday:

Synopsis:
Surface low pressure approaches from the central Great Plains and
crosses our region on Wednesday, bringing additional chances for
showers and thunderstorms, with a risk (level 1 or 2 out of 5)
for strong to severe storms and a marginal risk (level 1 out of 4)
for excessive rainfall. The strong / severe storm risk is
conditional, and will depend on the exact track of the low
pressure system, which is widely disputed among model guidance.

There is a chance for showers and thunderstorms to redevelop
Thursday, wrapping around the back side of the departing low
pressure. A deeper low pressure developing over the northern
Plains will drag a warm front northward across the region on
Friday yielding slight chances for showers and thunderstorms.
Behind the warm front, this weekend is looking very warm, with
inland highs around 90 in the forecast and a modest southwest wind
minimizing or even erasing the lake breeze.

Wednesday`s Conditional Storm Threat / Analysis:
The positioning and magnitude of CAPE varies widely from one
ensemble member to the next, largely dependent on whether the low
pressure system passes slightly north or slightly south of us. A
track just south of the region (northern IL) would allow
northeasterly winds off Lake Michigan to limit instability,
whereas a central WI track would pull the warm sector deep into
our region.

Ensemble and deterministic 500mb plots have a similar disagreement
on upper-level dynamics and whether or not shear will be
supportive of storm organization. A jet streak is expected east
of a shortwave trough somewhere nearby, and it`s proximity will
dictate the amount of southwesterly deep shear we will receive.
Ensemble mean plots center this jet streak over northern IL /
southern Lake Michigan / lower Michigan, with over 45 kt of
southwesterly flow (likely much faster in reality, given the
dispersion of model members).

Sheppard

&&

.AVIATION...
Issued 1224 PM CDT Tue Jun 17 2025

Sct-030-040 cumulus this afternoon with scattered storm
development over far S WI late this afternoon and early evening.
Additional showers and storms will then develop northward
through the night followed by widespread showers and storms for
Wed. MVFR Cigs will develop early Wed AM then fall mostly below
1 kft for Wed. Prevailing vsbys will range from 2-5SM due to
rain and BR.


Gehring

&&

.MARINE...
Issued 1224 PM CDT Tue Jun 17 2025

Low pressure around 29.5 inches will move from far northern Lake
Superior east into Quebec by late in the day. Its cold front
extending southward over Wisconsin will weaken and stall as it
moves into Lake Michigan later today and tonight. Areas of fog
will be possible tonight and Wednesday due to a relatively mild
and humid airmass over the cold waters of the lake.

Another low pressure area of 29.6 inches will cross eastern Iowa
Wednesday morning and reach central Lower Michigan by Wednesday
evening while strengthening to 29.4 inches. High pressure of 30.0
inches will set up over the Plains Thursday, with the top of the
ridge over Lake Superior and northern Lake Michigan.

Expect modest southerly winds this morning with winds becoming
light and variable late today and tonight as the front weakens and
stalls over the lake. Variable winds are expected for Wednesday as
low pressure moves across central Lake Michigan in the afternoon
and early evening. Modest north to northwest winds are then
forecast in the wake of the low for Wednesday night into Thursday
morning then turning westerly.

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