222
FXUS63 KARX 202349
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
649 PM CDT Thu Aug 20 2026

.KEY MESSAGES...

- Several rounds of scattered storms move through from west to
  east tonight through early Friday afternoon. Some of these
  storms could be on the stronger side.

- Seasonal temperatures persist well into next week with highs
  in the upper 70s to low 80s.

- Dry weekend with the next potential round of storms coming
  Tuesday and Wednesday of next week.

&&

.DISCUSSION...
Issued at 130PM CDT Thu Aug 20 2026

Tonight - Friday: Scattered Storms, Some Could be Strong

The main area of focus for the forecast deals with the evolution
of thunderstorms over the next 24 hours, first overnight and
again early Friday afternoon. Starting with this afternoon,
elevated light showers ongoing across central Minnesota are
progged to spread eastward with a region of 700-600-mb moisture
ahead of a weak mid-tropospheric wave. As these showers press
eastward and wane this evening, additional convection is progged
to develop back across central Minnesota closer to a
southeastward advancing cold front. This convection should be
outrunning the elevated instability axis and waning as they
arrive after midnight, though the latest HREF guidance keep the
band more or less intact along and north of I-90 towards
sunrise. Rainfall amounts in excess of an inch are possible with
any stronger cores, but other severe weather risks look low.

The main surface front will be lingering 6-8 hours behind this
early morning convection on Friday, stretching from roughly
Oelwein, IA to Wisconsin Rapids, WI by early afternoon. The
pre-frontal environment by early afternoon will be
characterized by MLCAPE values of 1500-2000 J/kg with minimal
inhibition. While the deep layer flow is not overly strong,
there is enough turning in the 0-6-km profile to support
organized cell structures capable of severe hazards. That all
being said, the window of opportunity for these storms to affect
the local forecast area is short-lived and any convection will
press east into south-central Wisconsin by mid-afternoon
(3-4pm). Given that the storms will likley be in the incipient
stage of development over the local area, large hail would be
the main threat with the tornado risk more focused to the south
and east into Illinois and southeastern Wisconsin.


Friday Afternoon - Monday: Dry and Seasonal

Longwave ridging builds over the High Plains during the day on
Friday with cool northwesterly flow and surface high pressure
in control through Monday. This will result in continued
seasonal temperatures and dry conditions.


Tuesday - Wednesday: Next Round of Storms

The medium range solutions are in good agreement that a
shortwave will crest the High Plains longwave trough late Monday
through Wednesday of next week, with this wave diving
southeastward through the region (possibly followed by
subsequent ripples in the flow). The attendant surface boundary
will interact with return southerly flow and bring the next
respectable risk for showers and thunderstorms to the region.
The exact timing and placement details of this rain will be
hammered out as we get closer to the event.

&&

.AVIATION /00Z TAFS THROUGH 00Z SATURDAY/...
Issued at 644 PM CDT Thu Aug 20 2026

Rounds of precipitation initially at 21.00Z TAF issuance
increase in storm potential through Friday morning potentially
affecting both TAF sites. Initial light rain at TAF issuance
progressing southeast while weakening caused temporary MVFR
visibility reductions.

Subsequent precipitation and storm chances remain higher west
and north of the local forecast area tonight into early Friday
morning. Therefore, have continued PROB30 as upstream storms
seen from Chanhassen RADAR remaining scattered while shifting
southeast along the Minnesota River Valley.

Subsequent FG/IFR-LIFR ceilings possible shifting south along
the Mississippi River Valley into early Friday morning before
additional storm chances along the resultant frontal boundary
through Friday afternoon.

&&

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

&&

$$

DISCUSSION...Skow
AVIATION...JAR