333
FXUS63 KARX 040956
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
500 AM CDT Mon Aug 4 2025

.KEY MESSAGES...

- Wildfire smoke persists today, primarily over Wisconsin.
  Impacts from the smoke are expected to decrease through the
  week.

- Shower/storm probabilities increase Wednesday evening
  (20-40%). Higher probabilities are expected this weekend.

- Temperatures and humidity increase through the week. Some
  areas could reach 90 degrees by the weekend.

&&

.DISCUSSION...
Issued at 244 AM CDT Mon Aug 4 2025

Wildfire Smoke Persists

Wildfire smoke continues to impact the surface today, primarily
across Wisconsin, but areas west of the Mississippi River may
see a resurgence of decreased air quality this afternoon given
southeasterly winds. Smoke may continue to linger across
portions of Wisconsin on Tuesday, but surface impacts are
expected to improve for the majority of the area. As the upper
level pattern becomes more active this week and surface winds
become increasingly southerly, a reprieve from our smokey
conditions is expected as smoke should begin to shift northward.

Shower/Storm Probabilities This Week

Several mid to upper level shortwave troughs traverse the upper
level pattern this week with shower and storm probabilities
increasing across our area in response, beginning Wednesday
evening (20-40%). However, the ridge over the Desert Southwest
builds northeastward into the Upper Midwest through the week as
well, with heights rising at 500hPa and temperatures increasing
in the 850- 700hPa layer. This ridge appears to provide enough
capping to keep the bulk of convection to our north and west,
along its periphery, which is supported by ensemble guidance as
the highest probabilities are portrayed to our north and west.
Instability builds under the ridge, so convection that is able
to develop in our area could lean towards the stronger side,
although the overall stronger storm threat is expected to our
west.

Higher probabilities of showers/storms come this weekend
(40-60%) as a stronger wave pivots eastward through the Northern
Plains. A surface front appears to move southeast towards the
Upper Mississippi River Valley during this timeframe with
instability building ahead of it. However, plenty of variation
exists with regards to the evolution of the thermodynamic/kinematic
profiles during this period, so will have to continue to
monitor over the coming days.

Warming Temperatures

As the aforementioned ridge builds northward, low level
southerly flow will usher higher temperatures and dewpoints into
the Upper Mississippi River Valley such that temperatures warm
into the mid to upper 80s by mid-week. The 04.00z ENS indicates
some areas, primarily valley locations, could reach 90 degrees
by the end of the week (40-60%) with probabilities of 90+
degrees increasing over the last few runs. However, the 04.00z
GEFS is less optimistic of higher temperatures and keeps
probabilities for 90 degrees across southern to central Iowa.

&&

.AVIATION /12Z TAFS THROUGH 12Z TUESDAY/...
Issued at 500 AM CDT Mon Aug 4 2025

CIGS: sct-bkn mid to high level clouds (generally 8+ kft) through
the period.

WX/vsby: another good setup for river valley fog this morning - but
the scattered to broken nature of the clouds will work against it.
Where it clears - fog. Where it`s more cloudy, not so much. Will
continue to monitor trends (satellite/obs) for possible inclusion
into the KLSE forecast. If realized, fog would quickly clear by 14z.

Same concerns for river valley fog Tue morning with variability in
clouds playing a large role in where it forms (and not).

Smoke still around, but generally continues to improve. Don`t expect
vsby impacts at this time.

WINDS: southeast under 10 kts.

&&

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

&&

$$

DISCUSSION...Falkinham
AVIATION...Rieck