803
FXUS63 KARX 221053
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
553 AM CDT Fri Aug 22 2025

.KEY MESSAGES...

- Showers and storms are possible this afternoon and tonight
  (20-50%). Some storms could possibly become strong to maybe
  severe in southeast Minnesota and north-central Wisconsin. If
  this does occur, it would occur more in the evening and
  likely dependent upon how much convection can develop this
  afternoon.

- Afternoon showers will be possible (up to 20%) on Sunday along
  and north of Interstate 94 in Wisconsin.

- Well-below normal temperatures (more early October-like) are
  expected from Sunday into Tuesday.

&&

.DISCUSSION...
Issued at 256 AM CDT Fri Aug 22 2025

Through Tonight

The 22.00z models are in general agreement that a shortwave
trough over eastern South Dakota will move east through the
region this afternoon. The 0-1 km ML CAPE is ranging from 1000
to 2000 J/kg in the CAMs. The highest CAPES are in the RAP and
NAM 3 km which have surface dew points around 70. Both the 0-3
and 0-6 km are less than 25 knots, so organized severe
convection is not expected. However, with DCAPES up to 1000
J/kg, could not rule out the potential for a downburst.

A second shortwave and surface cold front will move through the
area this evening. With the loss of diurnal heating, the 0-1 km
ML CAPES fall into the 500-1500 J/kg range. The 0-6 km shear
increases into the 35 to 40 knot range along and just behind the
cold front. This might result in a few strong to potentially
severe storms. With these 2 system moving through the area
within 6-9 hours of each other, the severe risk will likely
depend on how much convection occurs with the first wave. If
severe weather occurs, it will be likely be hail up to 1 inch in
diameter and wind gusts to 58 mph.

High temperatures will range from the mid-70s to around 80.

Saturday through Tuesday

Considering that a trough of low pressure will be moving
southeast through Wisconsin during peak heating on Sunday
afternoon, the NBM continues to look too dry for this time
period. Like last night, trended the forecast more toward the
ECMWF ensemble which has 43 of their 50 members with anywhere
from 0.01 to a tenth of an inch along and north of Interstate
94. For now added a 20% chance of showers along and north of
Interstate 94 in Wisconsin. These rain chances may have to
expanded and increased in coverage. The remainder of this time
period looks to be dry.

As high latitude ridging develops over Greenland, a longwave
trough will develop over the eastern half of the CONUS. This
will bring unseasonably cool temperatures southward into the
region. High temperatures will cool to around 70 for Saturday
and only top out in the mid- and upper 60s from Sunday into
Tuesday. Low temperatures will be around 50 on Saturday night
and in the 40s for Sunday and Monday nights. These temperatures
are more typical of early October than mid-August.

&&

.AVIATION /12Z TAFS THROUGH 12Z SATURDAY/...
Issued at 552 AM CDT Fri Aug 22 2025

Some tributaries and the Wisconsin River have fogged over this
morning. Other locations have a low stratus deck, roughly
between 3500 and 4500ft. The fog and low stratus deck are
expected to dissipate by the mid morning. Another round of low
to mid level CIGS (mainly between 4 and 7kft) moves in later
this morning/early afternoon. Shower and thunderstorm chances
increase (30 to 45%) for this afternoon and evening as a cold
front moves through the region. Light southwest winds today will
transition to northwest winds during the overnight period.

&&

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

&&

$$

DISCUSSION...Boyne
AVIATION...Cecava