863
FXUS63 KARX 062322
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
622 PM CDT Sat Sep 6 2025

.KEY MESSAGES...

- Scattered showers this afternoon (30-40% chance), especially
  north of I-90, that diminish in the evening.

- Unseasonably cool weather sticks around for the rest of the
  weekend before temperatures climb back to near normal by the
  middle of next week.

- Main shot of rain for the upcoming week looks to be late
  Monday through Tuesday (40-70% chance), though a few showers
  could linger off and on through the week.

&&

.DISCUSSION...
Issued at 1240 PM CDT Sat Sep 6 2025

This Afternoon/Evening: Cool with Scattered Showers

A large cyclonic bowling ball of arctic air remains entrenched
across the central U.S. today with an embedded shortwave trough
driving southward through northern Minnesota serving as the
focus for scattered showers later this afternoon. Given the
dynamic nature of the forcing and cooling of the mid-troposphere
with this wave, showers may linger for a few hours past sunset,
but the rapid loss of daytime heating should end the shower
risk by 9-10pm. Can`t fully rule out a rumble of thunder with
this afternoon`s shallow convection (10-20 percent chance) with
RAP/HRRR soundings hinting at the equilibrium level height
increasing past the -10 C level. A few lightning strikes have
already been noted north of the Twin Cities to verify this
thinking.

Cool Weekend, Warming Up Next Week

One last cold night remains on the docket for tonight before
surface high pressure passes off to the east and warm air
advection sets in. Lower tropospheric temperatures increase from
+2 to +15 C between this afternoon and Monday evening. At the
surface, this will result in daytime high temperatures steadily
increasing from the low 60s today to the mid-70s by Tuesday.
Further warming of the 925-700-mb layer during the remainder of
the week will be offset by cool northeast to southeasterly flow
off an eastern Great Lakes high pressure cell that builds
southward during this period. Pleasant highs in the 70s look to
hang tight for the second half of the week and into next
weekend.

Next Round of Showers Early Next Week

The increasing positive theta-e advection will result in an
increasing risk for showers and thunderstorms between Monday
afternoon and late Tuesday. Overall impacts and severity look
low at the present time with the main instability axis further
to the west. The exact coverage and placement of the showers
will be hammered out as we get closer to the time period.
Periodic bouts of warm air advection may be enough to generate a
few showers throughout the rest of the week, but confidence in
any details is low at the present time.

&&

.AVIATION /00Z TAFS THROUGH 00Z SUNDAY/...
Issued at 622 PM CDT Sat Sep 6 2025

As diurnal heating decreases, the showers will gradually
decrease in coverage this evening.

High pressure will build across the area tonight and remain in
control of the area through Sunday. With northerly surface winds
and strong winds aloft, valley fog will confined to the
Wisconsin River Valley and the tributaries.

&&

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

&&

$$

DISCUSSION...Skow
AVIATION...Boyne