114
FXUS63 KMKX 110215
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
915 PM CDT Thu Jul 10 2025

.KEY MESSAGES...

- Showers and storms remain likely (50-90%) into tonight.
  Locally heavy rainfall is the main risk, mainly along and
  south of I-94.

- Active weather continues Friday into Saturday, with additional
  periods of showers and storms likely (50-70%). Locally heavy
  rainfall and a few strong storms will be possible again.

- Mostly dry conditions are likely Sunday through at least early
  Tuesday, with shower/storm chances returning later Tuesday or
  Wednesday.

&&

.UPDATE...
Issued 830 PM CDT Thu Jul 10 2025

Rather complex, messy mesoscale weather pattern over the region
as an MCV and a series of mid level vorticity maxima will linger
through tonight.

The atmosphere is plenty moist and with high warm cloud depths,
the primary concern is heavy rainfall. With the axis of greater
instability to our southwest, and likely to remain shunted just
to our south, the risk for severe is low and limited to a wet
microburst or two.

The risk for showers and storms will remain over the region
through the overnight hours given the mess of vort maxes.
Though it appears the more concentrated, longer lasting
activity will be along/south of I-94 and closer to the WI/IL
state line where a low level boundary has taken shape this
evening. Heading into the overnight hours, a gradually veering,
modest low level jet will result in showers/storms slowly moving
southeast and deeper into IL. This is also supported by a
southeasterly oriented system motion vector.

That said, the CAMs have persistently hinted at bubbling
redevelopment over southeastern WI into much of the overnight
hours. Have updated PoPs to highlight this potential, and will
keep a wary eye on observed trends. Again, with all these vort
maxes loitering about, additional showers and storms
redeveloping over the area at any point tonight is plausible.

Heading into the daylight hours of tomorrow morning, it looks
like we get a break in the action. Stratus will eventually break
heading into the afternoon setting up our next chance of showers
and storms. Uncertainty remains above average for shower/storm
chances tomorrow afternoon as much depends on where MCVs and
boundaries eventually end up. Will keep the ongoing rain chances
going for now, but would not be surprised if alterations will be
needed, especially for western and northern portions of our
area.

Gagan

&&

.SHORT TERM...
Issued 255 PM CDT Thu Jul 10 2025

Tonight and Friday:

An area of showers continues to move in from the west this
afternoon, as a remnant MCV from overnight convection gradually
approaches. Thunderstorms are expected to redevelop in the
vicinity of the MCV by late this afternoon, likely within an
area of clearing where instability is higher. A few strong to
severe storms will be possible, particulary west of I-90, given
the instability along with shear that is likely being enhanced
by the MCV. Large hail, damaging winds, and even a brief tornado
will be possible if storms are able to get going this
afternoon. Storms may struggle to hold together as they head
east of I-90 given lower dewpoints and a generally more stable
environment with onshore winds.

Attention then turns to a heavy rainfall threat tonight into
early Friday. Models show persistent warm air and moisture
advection during this period, with a weak frontal boundary
generally stalled in the area. Precipitable water values will be
pushing 2 inches tonight into Friday and storm motion will
likely be on the slower side, with repeated rounds of storms
possible along the boundary. There is some uncertainty with
where this swath of heavier rain will set up, with a couple of
the latest mesoscale models shifting a bit southward. Generally
2 rows of counties north and south of the IL/WI border have the
highest chance to seeing the heaviest rain, with the picture
hopefully becoming a bit more clear over the next few hours.

There may be a lull in widespread precip mid Friday morning into
early afternoon, with a chance storms then develop along the
residual boundary by mid or late afternoon. Looks like enough
shear and instability for a severe threat again, with locally
heavy rainfall also possible. Not the highest confidence in high
temps tomorrow given uncertainty with how long clouds will
linger. Overall though, looks like highs within a couple
degrees of normal.

DDV

&&

.LONG TERM...
Issued 255 PM CDT Thu Jul 10 2025

Friday night through Thursday:

Stalled frontal boundary with southwesterly WAA from the surface
through 700 mb pointed into southern Wisconsin and Lake Michigan
by Friday night. Current trends are towards a semi-stationary
line of rain and thunderstorms across far southern Wisconsin,
although a significant amount of variability remains. NAM and Euro
indicate a more northern extent to the LLJ at 850 mb, keeping
convection alive across central to southern Wisconsin. This more
northern solution is dependent on phasing between a more well-
defined low pressure system traversing the southern Canadian
Prairies overnight and the remaining warm frontal feature from a
developing Colorado High Plains low. As the cold front from the
northern low approaches, phasing between the 500 mb waves would
allow for a stronger push of convective initiation across more of
southern Wisconsin. Regardless of exact placement of the frontal
boundaries and the amount of interaction between the two systems,
modeling is in firm agreement that PWATs of 1.75 to 2 inches will
be available to developing storms, in a deep warm cloud layer
environment. This will lead to high precipitation efficiency in
storms that do develop and enhance the heavy rainfall threat. The
main question that remains is the exact location of this axis of
precipitation. Therefore kept 40 to 60 percent chance PoPs in the
forecast for now. Confidence is high that storms will develop, but
low in placement. Will refine as the system develops and
confidence increases.

Saturday, high confidence in the northern low pressure system over
southwestern Ontario, bringing a neutral to negatively tilted
trough through northern to central Wisconsin. Unzipping along the
cold front into the lingering warm frontal boundary is also
possible as the weak low pressure in the High Plains ejects into
the central Plains through the day Saturday. Main questions for
southern Wisconsin remain forcing and CAPE. Primary 500 mb
shortwave remains to the north, with weak PVA across southern
Wisconsin from the lingering warm frontal boundary. 0 to 6 km bulk
shear values only around 20 to 30 kt, with the strongest shear
across central Wisconsin, and afternoon MUCAPE values between 1500
and 2000 J/kg. This favors primarily wet microbursts and perhaps a
few stronger storms capable of producing small hail. However,
morning overrunning precipitation may keep MUCAPE values lower for
the afternoon when the 500 mb trough makes its closest approach.
In addition, the surface cold front looks to lag behind the 500 mb
trough. If this front comes through later in the evening,
stronger storms become much less likely. All that said,
thunderstorms are likely (50 to 70 percent chance) during the
afternoon hours with multiple potential lifting mechanisms in
play.

Precipitation ends into Saturday night as the final cold frontal
push moves offshore into Lake Michigan, with northwesterly flow
bringing in dry conditions overnight into Sunday. Weak southerly
flow returns by Monday as low pressure develops in the northern
High Plains and ridging builds across the Plains into the Upper
Midwest. Temperatures may rise as high as 90 degrees Monday into
Tuesday as ridging builds, with scattered thunderstorms possible
within the warm and moist airmass (20 to 30 percent chance). Heat
index values currently expected in the lower 90s, but trends will
be monitored for high heat conditions. Chances increase (40 to 60
percent chance) into Wednesday as low pressure ejects eastward
and brings next major system to Wisconsin. Modeling in decent
agreement that this system will continue into the eastern Great
Lakes by Thursday night, but wrap around showers and storms remain
possible into Thursday (15 to 40 percent chance, highest in the
east).

MH

&&

.AVIATION...
Issued 915 PM CDT Thu Jul 10 2025

Complex aviation forecast over the next 24 hours as one round of
showers/storms affects portions of the area through the
overnight hours and another potentially develops Friday
afternoon into the evening.

A large area of rain and embedded storms will continue to slowly
move along and south of I-94 into the overnight hours.
MSN/UES/MKX will be on the northern edge of this rainfall the
rest of the evening. Scattered activity will remain possible
around MSN overnight, but the potential for additional rounds
of rain at UES/MKE exists.

Overall, VFR conditions are expected, but as rainfall lingers,
ceilings will eventually lower into the MVFR range, with a low
probability of IFR ceilings toward daybreak. Any visibility
restrictions would be more associated with rain/storms and will
be the exception rather than the rule. MVFR ceilings will
become broken with time during the daylight hours of Friday
morning, gradually lifting to VFR during the afternoon.

There is a good deal of uncertainty for shower/storm
redevelopment Friday afternoon into the evening. Much will
depend on where boundaries end up from activity tonight. The
better chances for redevelopment exist at JVL/UES/MKE/ENW and
have handled this with PROB30 for now. As confidence increases,
will hone in on location and timing. Heavy rainfall reducing
visibility to IFR or less will be the main concern.

Gagan

&&

.MARINE...
Issued 255 PM CDT Thu Jul 10 2025

High pressure of 30.0 inches overhead this afternoon will
gradually slide eastward tonight into Friday as a broad trough
of 29.8 inches slowly approaches from the west. Winds will
remain light and somewhat variable into tonight, becoming
southerly by Friday morning between the departing high and
approaching low. Winds will pick a bit out of the south on
Saturday as the trough nears, becoming westerly Saturday night
behind the trough.

Rounds of showers and thunderstorms are likely this evening
through tonight, mainly across the south half of the lake.
Shower and storm chances will then continue Friday night and
Saturday across the lake.

DDV

&&

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

$$

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