943
FXUS63 KARX 312259
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
559 PM CDT Thu Jul 31 2025

.KEY MESSAGES...

- Wildfire smoke is likely to persist into Saturday. This smoke
  will cause hazy skies, reduced visibilities, and decreased
  air quality in the red and possibly purple categories.

- Dry conditions are expected through the weekend. Still plenty
  of uncertainties on when rain chances will return to the
  forecast next week.

- Temperatures gradually warm from late this week into next
  week. Both 6-10 day and 8-14 day temperature outlooks are
  showing enhanced probabilities for warmer than normal.

&&

.DISCUSSION...
Issued at 100 PM CDT Thu Jul 31 2025

Through Saturday

A surface high pressure area will remain over the Upper
Mississippi River Valley and polar jet extends south into the
Upper Mississippi River Valley and Great Lakes. As a result both
the HRRR and RAP continue to show thick surface and elevated
smoke our area from the Canadian wildfires over the prairie
provinces, Northwest Territories, and Nunavut. The thickest
surface smoke look to be from tonight into Friday.

Additional elevated smoke from the wildfires over Utah and
northern Arizona will move into areas south of Interstate 90
through Friday night. This smoke is being advected to the area
by the subtropical jet which is located over the Central Plains
and Mid-Mississippi River Valley.

Air quality is forecast to remain in the red to possibly purple
at times through Friday with some improvement expected on
Saturday afternoon. Sensitive groups, such as people with lung
disease (including asthma), heart disease, and children and
older adults, should avoid prolonged or heavy exertion. The
general public should limit prolonged or heavy exertion.

Reduce or eliminate activities that contribute to air pollution,
such as outdoor burning, and use of residential wood burning devices.
Reduce vehicle trips and vehicle idling as much as possible.

Keep windows closed overnight to prevent smoke from getting
indoors.

With the thick smoke limiting the warming across the region
today and little change expected for Friday, the Friday maximum
temperatures were lowered using the latest CONSShort. This
resulted in high temperatures in the lower and mid-70s. With a
little bit less smoke expected on Saturday, stayed closer to
the NBM maximum temperatures forecast (in the 70s) for Saturday.

Sunday Night into Thursday

The winds gradually become move zonal over the northern CONUS.
This will in turn allow northern shortwave troughs to move east
and southeast through the region. Like the past couple of days,
there are still plenty of uncertainties on when exactly that
will occur. The operational GFS starts to bring rain chances
into the area as early as Sunday night and Monday. Meanwhile,
ECMWF ensemble shows this not taking place until the middle to
latter parts of next week.

High temperatures will warm from the mid-70 to around 80 on
Sunday into the mid- and upper 80s by mid-week.

&&

.AVIATION /00Z TAFS THROUGH 00Z SATURDAY/...
Issued at 557 PM CDT Thu Jul 31 2025

VFR to MVFR conditions currently present with wildfire smoke
creating some HZ and dropping visibilities to between 4-7 miles
across much of the area. This smoke is expected to linger
through the period so have kept visibilities in the high-end
MVFR range for much of the time. Amendments based on surface
observations may be needed going forward as high-resolution
models have not done a good job at representing just now much
near surface smoke is being realized across the Upper
Mississippi Valley. As temperatures cool overnight, there is a
chance we could see some patchy fog/smog develop at the
terminals. Due to dew point depressions not being as low as
desired for more dense fog, did not have enough confidence to
drop visibilities below MVFR for the time being. Any fog/smog
that develops should dissipate after 12Z, leaving hazy
conditions to linger through the afternoon. Winds will be light
and variable overnight, becoming more east/northeasterly by
tomorrow afternoon at less than 8 kts.

&&

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

&&

$$

DISCUSSION...Boyne
AVIATION...Barendse