540
FXUS63 KMKX 072009
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
309 PM CDT Mon Jul 7 2025

.KEY MESSAGES...

- Drier and more comfortable conditions expected through this afternoon.

- Shower and thunderstorm chances (~30-55%) return Tuesday,
  though an all-day washout is not expected.

- Additional shower and thunderstorms forecast Friday through
  Saturday ahead of the next disturbance.

&&

.SHORT TERM...
Issued 309 PM CDT Mon Jul 7 2025

Tonight through Tuesday night:

Partly cloudy to mostly clear skies across much of south central
and eastern Wisconsin. Daytime heating has brought temperatures
up into the mid 70s to low 80s and drier air is slowly working
in from the north. Across far southwestern Wisconsin, isolated
rain showers have developed. These showers are in a good area of
CAPE with some diurnal lift. This narrow area will slowly move
southeast with time and will nick part of western Lafayette and
Iowa counties. Dewpoints are in the upper 60s across far
southwestern Wisconsin which is good enough to support these
showers. As we loose sunlight and drier air begins to push
further westward the window for isolated rain showers will end.
If storms get tall enough there could be a few rumbles of
thunder, but there is very little shear in Wisconsin and overall
rain motion is very slow around 10 to 15 kts. Rain should pulse
up and fall back down and outflow boundaries that fan outward
could produce some more rain showers so will have to keep an eye
on that and increase POPS accordingly. There is no risk for
stronger or severe weather with these showers.

Conditions will briefly dry out again late this evening into early
tonight for southwestern Wisconsin. An upper trough and weak sfc
front will advect eastward into Wisconsin Tuesday bringing our next
chance for rain and thunderstorms. Precipitation is expected to
begin early Tuesday morning in the predawn hours with a
scattered line moving east across the area. CAMs again are all
over the place with timing and exactly how this scattered line
will move through so kept POPs more broad and a bit lower around
35 to 60%. This line should work eastward through the Tuesday
morning commute exiting to the east by mid morning. This however
will not be the end to our rain chances for the day. This
initial line will set the stage for isolated to scattered storm
development through the afternoon and into the evening. You can
already see this line move southeast to the NW in Minnesota and
the Dakotas. If this line does become more of an MCV as it rolls
through instead of a broken line then more widespread rain and
more develop from outflows are expected through the afternoon.
Upper level lift will be over the Great Lakes Region for much of
the day with some better shear so a more scattered or weaker
line, could lead to unsettled clouds and isolated pockets of
rain/storms throughout the day as mixing and sfc lift increases.
Tuesday wont be a complete wash out of constant rain, but more
of a few rounds of scattered to isolated development. While
there will be some more shear in comparison to today, there isnt
any organized convection anticipated. So not anticipating
stronger or severe storms from any activity Tuesday. A few
storms could produce some brief heavy rainfall and lightning.

Tuesday night into Wednesday morning the pesky showers chances
remain around 20-30% or less. The low pressure system will again be
slow to exit the Great Lakes region, leaving broad lift across
southern Wisconsin. In this type of environment, CAMs again are all
over the place, but the next potential for rain heading into
wednesday morning will likely be across south central to
southeastern Wisconsin and these chances will decrease from the
northwest to the southeast overtime.

Patterson

&&

.LONG TERM...
Issued 309 PM CDT Mon Jul 7 2025

Wednesday through Monday:

An upper level ridge will move into the Great Lakes Region Wednesday
and begin exiting to the east early Thursday. Despite the large
scale subsidence, there will be some mid level and low level
transient lift to keep in some low chance POPs for both days (10-15%
or less). Majority of the area will remain dry and quite, but for
the few expectations here`s the break down. For Wednesday, the
frontal boundary from Tuesday will again be slow to exit to the
southeast. So rain will linger through the morning hours.
Heading into the afternoon the sfc low will be just to our south
in the Ohio River Valley which will leave some broad weak lift
across our forecast area. Only a few models are picking up on
this (the NAM being one of them) and dewpoints should remain in
the 60s. So there could be enough lift to squeeze out some
isolated showers, but more likely is partly cloudy to overcast
skies. Timing and exact locations for this 10% chance of rain
vary wildly.

Now for Thursdays very small chance, there will be a stationary
front that will wiggle around central Illinois. There will be sfc
high pressure to our north, but these very low chances (10% or less)
hinge on the few runs of guidance that have this boundary drifting
more northward overtime. Should this occur, southern Wisconsin would
again have weak board lift and dewpoints in the 60s. So just
enough moisture and lift to get isolated showers. Now, the
bright side is chances are low and the vast majority of southern
Wisconsin will remain dry both days. Highs will be pleasant and
warm in the upper 70s to mid 80s both days.

Friday into Saturday the ridging breaks down and moves eastward as a
stronger trough and sfc low pressure system advect toward the state.
Friday afternoon into Friday night will be the best chance for rain
through the extended with POPs of     . There should be decent upper
level support as Wisconsin will be on the leading edge of this
stronger upper level low. There will be some interesting
phasing as a shortwave tries to move out ahead of the main
trough. So no shortage of upper level  support, but phasing
issues could weaken the overall effectiveness for stronger
storms and broaden the window for rainfall. There is a lot  of
uncertainty on the track of the sfc low with some models trying
to bring it through southern Wisconsin and other opting for a
more northward track. The farther north the track goes the more
likely our forecast area is to end up in the warm sector and get
good instability for storms. Another thing to keep an eye on
for this system is moisture will be increasing and so to will
PWATs. Heavy rain will be possible with high PWATs, but this
system is expected to be more transient and move through
quicker. While no day will be a washout of rain, its a good week
to keep an eye on the forecast.

Through the rest of the weekend and into next week there is still a
lot of uncertainty so low chance POPs sneak in yet again. As
the upper level trough and sfc low exit Saturday, models are
split on the timing and strength of another trough/low right on
the heels of the first. The GFS seems to be the most amplified
and fastest, but too much uncertainty to draw meaningful
conclusions on rain/storms. Temperatures will remain consistent
through the extended with highs in the mid 70s to mid 80s.

&&

.AVIATION...
Issued 309 PM CDT Mon Jul 7 2025

Largely VFR conditions are expected to continue today. High
pressure will be moving in from the west today, which will keep
winds light and variable for all of southern Wisconsin. Isolated
rain and storms have developed across the Mississippi River
Valley and into the Wisconsin River Valley this afternoon.
These rain showers will be slow moving and be pulse in nature,
coming up and fall apart quickly. The tallest of these showers
will be able to produce a little bit of lightning and some
moderate to heavy rainfall. Far western terminals, LNR and MRJ,
are the only ones likely to be impacted by any of these
showers/storms as they are very slowly moving and anchored to a
narrow band of sfc lift. Everywhere else will remain dry through
today and into early tonight.

A low pressure system and trough will approach the region
overnight into Tuesday morning bringing more widespread rain to
the state. The earliest a scatttered light of rain could move
through would be around and just before the morning
commute. Some MVFR ceilings and visibilites are expected with
these showers/storms. Scattered to isolated storms are possible
throughout the day Tuesday. Timed in the initial line of
rain/storms into TAFs tomorrow morning. Beyond that limited the
mention or rain and PROB30s as there is alot of uncertainty in
timing and placement of any additional rain.

Patterson

&&

.MARINE...
Issued 309 PM CDT Mon Jul 7 2025

High pressure in the Hudson Bay remains as low pressure
continues to exit the region to the east. Winds have come down
today as the pressure gradient has weakened. A second weak area
of surface high pressure will move through tonight and cross
Lake Michigan bringing light and variable winds. This are of
high pressure will quickly move east and winds behind the high
will become south to southeasterly.

On the heels of this exciting sfc high a broad low will move
into the Upper Mississippi River Valley. The low will pull a
weak surface front across Lake Michigan Tuesday night, resulting
in a northerly wind shift. Areas of showers and thunderstorms
will accompany the approaching boundary, with severe weather not
expected at this time. North to northeast winds will remain
entrenched through Thursday. Winds will turn out of the
southeast on Friday as a second area of 29.8 inch low pressure
moves into the Great Plains. The low`s approach will bring
additional chances for showers and thunderstorms to the open
waters Friday into Saturday.

Patterson

&&

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

$$

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