752
FXUS63 KARX 192256
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
556 PM CDT Tue Aug 19 2025

.KEY MESSAGES...

- Isolated showers and perhaps a rumble of thunder are possible
  (10-20%) this afternoon. Fog is expected to develop again
  Wednesday morning and may become dense in some areas.

- Showers and storms may return Friday (10-30%) as a cold front
  moves through the region.

- Below normal temperatures are expected this weekend into early
  next week.

&&

.DISCUSSION...
Issued at 137 PM CDT Tue Aug 19 2025

This Afternoon and Wednesday

Isolated showers are possible this afternoon into the evening
hours associated with weak surface convergence aided by various
bits of shortwave energy aloft running along northwest flow.
Can`t rule out some rumbles of thunder with any showers this
afternoon as CAPE values climb to 1000-1500 J/kg with surface
dewpoints in the upper 60s to low 70s. The highest confidence in
showers this afternoon/evening reside along and north of I-90
with much of the area expected to remain dry.

High pressure builds into the region this evening and overnight
associated with the aforementioned ridge, bringing drier air
and clearing skies to the region. Given ample moisture in the
low levels remaining from the rainfall this past weekend, fog is
possible again overnight, possibly dense in some areas. Fog
should begin to mix out by mid-morning Wednesday.

Storm Potential Friday

A stronger shortwave propagates eastward along the United
States/Canada border late this week with surface cyclogenesis
expected to occur over Manitoba/Ontario in response. A surface
cold front associated with these features digs southward into
the Upper Midwest as southwesterly to southerly surface flow
ushers warmer and more moist air into the region. Instability
builds ahead of the front to 1000-2000 J/kg with some elongation
noted in the hodographs. As such, showers and thunderstorms are
possible (10-30%) along the front as it moves through the
region. Questions remain regarding coverage and intensity as
models depict weakening moisture transport as the front moves
into our area, resulting in decreasing probabilities with time
in the 19.13z NBM.

Drier conditions are expected in the wake of the cold front, but
additional showers may develop Saturday afternoon in the cyclonic
flow on the backside of the surface low.

Below Normal Temperatures This Weekend and Early Next Week

Temperatures begin to fall this weekend associated with cold
air advection behind the aforementioned cold front. The 19.00z
EFI currently indicates anomalously cold temperatures are
favored for both the highs and lows as we head into early next
week, with 60-80% of the members indicating this scenario.
Confidence in below normal temperatures is further increased
with the consistent trend in cooler temperatures noted in both
the ENS and GEFS, although the exact high/low temperatures
remain in flux which may be attributable to factors such as
cloud coverage. Overall, high confidence that more fall like
temperatures are on the horizon.

&&

.AVIATION /00Z TAFS THROUGH 00Z THURSDAY/...
Issued at 557 PM CDT Tue Aug 19 2025

Currently monitoring some showers and storms across southeast
Minnesota and northeast Iowa. With the loss of diurnal heating,
they should dissipate quickly within the next 3 hours. At this
time, thinking that they will miss the TAF sites.

With generally clear skies, wet soils, and light winds up to
900 mb, there will be enhanced chances for widespread fog to
develop overnight tonight and on Wednesday morning. KRST still
looks like it will have a better chance of dense fog than KLSE,
so added some dense fog there and just lowered the visibilities
to MVFR at KLSE for a few hours.

&&

.HYDROLOGY...
Issued at 137 PM CDT Tue Aug 19 2025

Impacts from the weekends rain continues this afternoon and
will likely continue overnight into Wednesday. Several rivers in
northeast Iowa to southwest Wisconsin, most notably the Cedar,
Turkey, and Kickapoo rivers, have responded the most and remain
in moderate or minor flood stage (primarily the Cedar and
Turkey rivers), or are forecast to reach minor flood stage in
the next day. Areas along the Kickapoo have seen a downward
trend in river stage the such that these areas may only reach
action stage. River Flood Warnings and River Flood Watches
remain in effect.

&&

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

&&

$$

DISCUSSION...Falkinham
AVIATION...Boyne
HYDROLOGY...Falkinham