048
FXUS63 KMKX 240902
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
402 AM CDT Tue Sep 24 2024

.KEY MESSAGES...

- Showers for southeastern Wisconsin today with a small potential
for heavy rainfall rates over the far southeast.

- A small potential for waterspouts over southern Lake MI for today
and tonight.

- Mild and Dry conditions for Wed-Fri.

&&

.SHORT TERM...
Issued 402 AM CDT Tue Sep 24 2024

Today and Tonight:

A low pressure system is advancing toward southern Wisconsin
today. This low is expected to pass through northern Illinois
before moving northeast into southwestern Michigan. With the
state on the northern side of low pressure system, expecting
rain to move through the southern and eastern portions of the
forecast area tonight through this evening until the low
pressure system has moved out of the area. The best time for
rain are expected to be this morning and early afternoon.
Moisture advection is expected to wrap around the low pressure
system as it advances northward which will moisten the mid to
low levels, bringing PWATs up to around 1 to 1.5 inches. Along
with the higher PWATs there is a chance for some banding to set
up along mid level Frontogenesis which brings the potential for
heavy rainfall. Far southeastern Wisconsin looks to have the
best chances for the heavier rainfall. There will also be a
small chance for a few rumbles of thunder again mainly across
far southeastern Wisconsin where the support from the low
pressure system is at its greatest for southern Wisconsin.

Across Lake Michigan there is a chance for some waterspouts with
the convective rain and thunderstorms early this morning through
tonight. For more information on the waterspout potential be
sure to check out the Marine discussion.

Patterson

&&

.LONG TERM...
Issued 402 AM CDT Tue Sep 24 2024

Wednesday through Monday:

Mid week and into the weekend high pressure/ridging will set up
across the Great Lakes Region with an upper level low to the
south (Rex Block Pattern). The low is expected to get cut off
from the main flow as the ridge builds and strengthens, this
will keep conditions dry and quiet across the state through the
rest of the work week. From here we will look toward the
development of a tropical system in/near the gulf. The strength
and timing of this system will play a roll in how this blocking
pattern breaks down for the weekend. Guidance has these two low
pressure systems, one being the cut off low and the other being
the tropical system, pivoting around one another as we head into
Friday. Depending on how these two system interact we could see
some precipitation advect up into the southern Great Lakes
Region or stay further south and east. There is quiet a bit of
uncertainty still in how this will evolve so stuck close to the
average among model guidance through the weekend.

Patterson

&&

.AVIATION...
Issued 402 AM CDT Tue Sep 24 2024

IFR to VFR conditions are expected to persist through the
period. Moderate to heavy rainfall is moving in from the
southwest this morning along the northern edge of an advancing
low pressure system. This low is expected to pass through
northern Illinois into southwestern Michigan. Chances for
lightning will be low and contained to far southeastern
Wisconsin. Cooler temperatures and small dewpoint depressions
will also lead to some low stratus and fog development. Between
the rain and fog potential, expect visibilities to fall between
2-5 SM. Fog will be possible across southern Wisconsin through
this morning while the rain chances will be mostly for southern
and eastern Wisconsin. The terminal with the highest chances for
rain will be Milwaukee and Kenosha. Any fog that develops will
burn off after sunrise while rain chances are expected to
persist into the evening hours before decreasing.

A cloud deck around 1 kft to 3 kft will move in with the rain.
Across western and central Wisconsin this lower cloud deck will
be mostly scattered with some higher clouds around 10 kft. North
to northeast winds today will become northwesterly tonight.

Patterson

&&

.MARINE...
Issued 402 AM CDT Tue Sep 24 2024

Weak high pressure will remain northeast of Lake Superior while
low pressure tracks from southern IL to southern lower MI
today. This will bring the chance for thunderstorms and
waterspouts over southern Lake MI. The low will also maintain
modest east to northeast winds shifting northerly for tonight
and Wednesday as the low moves away.

Predominately north to northeast winds are expected across the
lake until Wednesday when they briefly take on a westerly
component. Light and variable winds are expected Wednesday
night.

The potential for waterspouts is expected to be across the
southern half of the lake where there will be some convective
rain and a few thunderstorms. The delta Ts between the water and
850mb is roughly around 10 to 15 degrees. The upper level low
pressure is expected to dig southward moving toward the mid
Mississippi Valley this morning before shifting eastward into
the Ohio River Valley which puts the southern portion of the
lake roughly in the northeastern quadrant as well, which can be
a favorable zone for waterspout development this time of year.
Even at the low moves eastward throughout the day any cloud
depths that reach roughly 30 kft could pose a problem as well. A
pretty dynamic situation for the southern half of the lake with
the one main detriment being the 850 mb winds are a bit lack
luster. The main take away from all of this is that where there
are low clouds and rain, the chances for waterspouts will be
likely throughout the day and into tonight.

Patterson

&&

.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