872
FXUS63 KARX 101810
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
110 PM CDT Sun Aug 10 2025

.KEY MESSAGES...

- Heavy rainfall and flooding possible across southwest
  Wisconsin and adjacent northeast Iowa through the day (20%
  chance of over 3"). A Flood Watch remains in effect there, but
  now ends earlier (7pm) as the heavy rain threat will shift
  east of the area tonight.

- Rain chances were increased (50-areawide today as a weather
  system tracks from southwest to northeast across the area this
  afternoon.

- A tranquil pattern is setting up for the next week with low
  rain chances and temperatures near seasonal normals. Some warm
  up possible late week.

&&

.DISCUSSION...
Issued at 343 AM CDT Sun Aug 10 2025

Todays Heavy Rainfall Threat, Early Ending to Flood Watch

Current 3 am radar depicts an axis of storms from southwest WI
back to southwest Iowa associated with an increasing low-level
jet and moisture transport axis. A bit troubling is the linear
band to the storms parallel to the flow - this sets up a
training situation. That axis and air mass is still the potent
rain maker with near-record precipitable water (Davenport IA
sounding at 7pm Sat - 1.91") and deep warm cloud depths over 4
km. Some of that materialized north of La Cross through
Rochester with a 5" band of rain Saturday. Over 9 inches of rain
fell in the Milwaukee area tonight from that air mass in repeat
storms. SPC mesoa shows MUCAPE of about 3000 J/Kg over IA/IL,
decreasing northward to about 1k on I-90, so plenty of
instability. Eyes are also on the convective swirling complex in
southeast Neb which has begun to lift northeast toward the
area. Rainfall observations show 1.46"/hr in Lincoln Neb in the
last hour.

Predictability remains fair to okay with this pattern but the
model guidance has clear disagreements between the global and
CAM solutions with the evolution of the rainfall axis and very
potent rainfall axis. The global models, which have a north
bias (toward stable air) to heavy rain, continue to show these
differences through Monday while CAM solutions agree that the
heavy rainfall threat ends today. Tend to give the nod to the
CAMS when convectively driven evolution is important....like
today.

Storms will continue to develop and repeat this morning south
of I-90 mainly, with the potent rain axis across southwest WI
and adjacent northeast IA. At the same time, the Nebraska
convectively-enhanced vortex will track toward the area,
arriving in northeast IA by mid/late morning and causing a
showery Sunday with isolated storms for much of the afternoon
across the area. This convective vort max will also provide a
progression to the weather, and an end to any repeat storm
activity in the Flood Watch in SW WI and NE IA, and overall
clear the weather east of the area by early evening. Thus, have
increased rain chances quite a bit across the forecast area as
the vort max transits today per HRRR guidance - which has been
very consistent run-to-run and the radar is supporting its good
handle on the forecast. Flooding risk is mainly this morning
before the vort max disrupts the training setting up.

Rain amounts today across the Flood Watch look to be in the
1-3" range depending on the amount of repeat storms occur.
Should any repeat/anchored storm pattern setup, rainfall rates
of 1"/hr will quickly add up. The 10.00Z HREF suggests 20%
probabilities of 3" in the Flood Watch. Tonight and Monday,
those probabilities shift southeast of the area and drastically
lower /20% chance of 1"/. Today, the HREF QPF max is 6-7" which
is always unsettling as a ceiling and the local prob matched
mean, a better measure of realistic amounts vs the mean, is
4-5". This reinforces the Flood Watch is valid today and we need
to watch rainfall totals through the morning in this training
regime that has developed now on radar. Since this area saw
very little rain Saturday, the soils can take 3" without much
problem, thus flooding risk has decreased overall. Without a
second heavy expected tonight, have changed the expiration time
on the Flood Watch to 7 pm today.

Seasonable August Weather Next Week

A zonal flow pattern will take over for much of the week with
weak impulses moving through causing low rain chances. A bit
stronger shortwave trough and front in northwest flow sweeps
through Tuesday to bring in some lower dewpoint air for a couple
days before ridge and heat building probabilities increase for
late week /highs in the 90s/. The Tuesday front may bring some
showers with it.

&&

.AVIATION /18Z TAFS THROUGH 18Z MONDAY/...
Issued at 110 PM CDT Sun Aug 10 2025

Showers/storms from this morning have dissipated across the
region this afternoon. Additional showers have developed across
south-central Minnesota and north-central Iowa and are expected
to propagate eastward through the afternoon, although not
overly confident in the eventual evolution of them through our
region. Greater confidence in additional showers/storms
developing in eastern Iowa and moving into far southwestern
Wisconsin from 21z-00z.

Mist/Fog is expected to develop again tonight into Monday
morning given the ample moisture from the rainfall of the past
few days. MVFR/IFR visibilities are possible across the region
through the morning hours with the fog.

&&

.HYDROLOGY...
Issued at 343 AM CDT Sun Aug 10 2025

Most rivers near and north of I-90 have handled the 3-5" rains
well with rises but little flooding.

Rivers located in the Flood Watch across northeast Iowa into
southwest Wisconsin will be the most susceptible to flooding,
most notably the Turkey River and Kickapoo River. Ensemble
guidance indicates that most points along these rivers should
remain either below or nudge into Action Stage given the most
likely rainfall amounts of 1 to 3 inches. Values above 5 inches
could result in rises along the Turkey river reaching Minor to
Moderate Flood Stage (5-10% chance), while values of 3-4 inches
(10-20%) would be needed for Minor flooding on the Kickapoo.

&&

.ARX WATCHES/WARNINGS/ADVISORIES...
WI...Flood Watch until 7 PM CDT this evening for WIZ054-055-061.
MN...None.
IA...Flood Watch until 7 PM CDT this evening for IAZ029-030.

&&

$$

DISCUSSION...Baumgardt
AVIATION...Falkinham
HYDROLOGY...Baumgardt