344
FXUS63 KARX 161038
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
538 AM CDT Wed Jul 16 2025

.KEY MESSAGES...

- Showers and storms impact the region this morning through the
  evening. Some of these storms could be strong to severe in
  southwestern Wisconsin this afternoon with damaging winds
  being the main threat.

- Locally heavy rainfall is the main concern with these storms.
  Current forecast has a swath of 1 to 1.5 inches across the
  I-90 corridor, with some locally higher amounts possible.

- Cooler temperatures for the end of the week with highs in the
  70s and low 80s from Thursday through the weekend, then
  gradually warming up into the middle of next week.

&&

.DISCUSSION...
Issued at 411 AM CDT Wed Jul 16 2025

Today: Showers and Storms, Flood Potential?

Ingredients are coming together for showers and storms today
however, there are still some uncertainties with regards to storm
intensity and coverage. At the surface, a low pressure system is
slated to move through our CWA during the morning and afternoon.
With each new CAM run that comes across, the direct trajectory of
the center of the the low continues to wiggle a little north and
south but general consensus has the center of the low moving
directly over much of the CWA. The path that this low takes will
have a role in where the heavier rain falls. With good 850mb
moisture transport for areas along and east of the Mississippi
River, PWATs between 1.75 and 2.10 inches, and a deformation zone
north of the low, there is some potential for heavy to fall. WPC has
placed much of the forecast area in a Slight risk for flooding due
to these conditions. Current forecasted QPF amounts have between 1
to 1.5 inches for areas along the I-90 corridor, with the highest
amounts in west central Wisconsin. Within the deformation band, LPMM
from the 00Z HREF shows a swath of 1 to 2 inches along the I-90
corridor and pockets of 2 to 4 inches in some of the worst case
scenarios. Outside of this corridor, most places should receive
between 0.25 and 0.75 inches, with some localized higher amounts
from convection. With all this being said, the storms will be
progressive which helps reduce flooding potential a little, but with
amount of available moisture, can`t rule out some localized flooding
in locations.

As far as the severe potential goes, there is a narrow window for
stronger storms to occur, roughly between 11am and 4pm. Depending on
the path the low takes will determine how deep the warm sector is.
Low level shear remains lower (between 10 and 20kts), while 0-3km
shear is slightly better (between 30 and 40kts). With the enhanced
winds aloft and the surface low nearby, SPC has gone ahead and
issued a slight risk (level 2 of 5), for most of western Wisconsin
within our CWA. If storms can initiate, then damaging winds would be
the most likely hazard as the warm cloud depth is too deep for
severe hail to occur. Closer to the surface low, a tornado or two
cannot be ruled out with the enhanced shear from the low.

Thursday-Friday: Mostly Dry, Cooler

Cooler and drier air plunges southward from Canada as a surface high
moves through the Upper Midwest on Thursday and Friday resulting in
a nice break from the warm and muggy conditions we have been
experiencing. Dewpoints will also drop into the low to mid 50s for
Thursday and the mid 50s to low 60s for Friday. Temperatures are
forecasted to be in the low to mid 70s for Thursday and the mid to
upper 70s for Friday. With mild daytime temperatures, the overnight
lows for Thursday night could fall into the upper 40s (NBM 25th
percentile) for areas north of I-94 depending on the amount of
cloud cover.

Saturday-Wednesday: Potentially Active Pattern, Warmer

An active pattern looks to resume as the Upper Midwest shifts to a
zonal pattern. This will allow for multiple shortwaves to move
through the region into the middle of next week. The first couple of
disturbances move through Friday night/Saturday morning and again
Saturday night/Sunday. These are looking like MCS`s that move along
a surface baroclinic zone stretching from eastern South Dakota
towards northern Illinois. Current LREF 75th percentile QPF has
between 0.25 and 0.5 inches across the forecast area by Saturday
night. These MCS`s, if they track anywhere over our CWA, could
produce moderate to heavy rain. Details on these systems will work
themselves out as we get closer. Outside of this weekend, low PoPs
(mostly 20 to 30%) are in the forecast into the middle of next week.
While most of the CWA has rain chances, the better chances will be
where the surface baroclinic zone sets up each day. Temperatures are
looking to gradually warm back up into the mid and upper 80s by
Tuesday.

&&

.AVIATION /12Z TAFS THROUGH 12Z THURSDAY/...
Issued at 538 AM CDT Wed Jul 16 2025

Main taf concerns today will be convection and MVFR/IFR
conditions at both RST/LSE taf sites through much of the taf
period. Surface low will track across the area today.
Convection will redevelop around the surface low this morning
and continue into this afternoon. Conditions will lower into
IFR/MVFR with the convection impacting the taf sites this
morning and into this afternoon. As surface low moves east of
the area late this afternoon/this evening...low stratus deck
clouds will move over the region and allow for IFR conditions at
both RST/LSE taf sites for the rest of the taf period. Winds
will shift to the north and wind speeds will be up to 10 knots
this afternoon into tonight.

&&

.ARX WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
IA...None.

&&

$$

DISCUSSION...Cecava
AVIATION...DTJ