873
FXUS63 KARX 111916
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
216 PM CDT Fri Jul 11 2025

.KEY MESSAGES...

- Heavy rain and storms progress northeast through northeast
  Iowa, southwest Wisconsin, and central Wisconsin through the
  daytime hours. Highest rainfall amounts expected along
  southern peripheral counties where 1"+ of rainfall is possible.

- Low confidence in limited precipitation chances through start
  of new week, eventually increasing Tuesday, lasting through
  Wednesday.

&&

.DISCUSSION...
Issued at 209 PM CDT Fri Jul 11 2025

Tonight: Strong Storms and Heavy Rain Possible

Elevated convection behind a warm front/baroclinic boundary is
starting to pop up across portions of northeastern Iowa early this
afternoon. Many of these storms are meager at best with better
instability residing much further south into central and
southern Iowa where SBCAPE is greater than 1500 J/kg. A surface
low is currently located across far southeastern Nebraska with a
convectively reinforced upper level shortwave present across
Iowa in 18Z 500 mb analysis. As we are north of the warm front
and quasi baroclinic boundary, the severe threat overall looks
pretty marginal but there is a minor threat for large hail with
these initial storms, becoming more of a damaging wind threat
later on (especially across far southwestern Wisconsin with
DCAPEs greater than 500 J/kg) as they will likely grow upscale
into more of a MCS/QLCS type feature with time. Vertical shear
overall is marginal at 20-30 kts with some pockets of 35 kts
across our far southern counties, being aided/enhanced by the
shortwave trough. The severe threat will continue through the
afternoon and into the evening, likely waining after 00Z.

While the severe threat isn`t looking overly impressive for our
area, the threat for heavy rain looks much better. Areal pWats sit
at 1.5-1.8 inches and warm cloud depths are approaching 3 kft. Any
storms will likely be efficient rainfall producers so if we see any
training activity, this could lead to signficiant ponding or
localized flooding. 11.12Z HREF mean precip totals look to be in the
.5 to 1.25 inch range for Northeastern Iowa and Southwestern
Wisconsin with lower totals to the north. Due to the convective
nature of the storms, there remains some pretty significant
differences in the 75th-25th percentiles with the 75th around 1.5-2
inches and the 25th percentile less than .25 inches. Unless we start
to see some excessive training, the mean HREF totals look
reasonable. Recent (last 24 hours) rainfall across Grant/Clayton
counties were generally less than 1.25 inches with the heaviest
rains staying south of our area more towards Dubuque, Delaware, and
Buchanan counties. Soils and rivers across the area should be able
to handle the rain, keeping widespread flooding concerns at bay for
the time being. A "cold front" associated with a surface low across
Western Ontario will push unto our area later tonight which could
bring some additional low end rain chances through the overnight
hours before exiting our area through the day Saturday. Rain chances
should generally be over by 12Z for areas west of the Mississippi
with low chances (20-30%) lingering into the afternoon before moving
off to the east.

Sunday - Monday: Likely Dry, Warming Temperatures

A weak surface high is expected to build into the Mid-Mississippi
River Valley behind the cold front, likely keeping conditions dry
for Sunday into Monday. We`ll see more abundant sunshine across the
area, which will allow for temperatures to start climbing back into
the mid to upper 80s by Monday with a few places maybe even reaching
the 90 degree threshold. With a broad upper level ridge building
across the southern CONUS, our area will be in northwest to weakly
zonal flow through the start of next week. A stray shower cannot be
ruled out Sunday night, especially across north-central Wisconsin,
but the general trend should remain dry.

Tuesday and Beyond: Wet Mid-week with Cooler Temperatures

WPC cluster analysis and mid range models are hinting at a weak
trough axis developing across the Northern Rockies and subsequently
moving east into our area Tuesday into Wednesday. These features are
not well resolved in the mid/long range models but moisture will be
reinforced by then with south to southwesterly surface flow helping
to deepen areal moisture. As the cold front moves through, PoPs
increase to likely (50-70%), especially during the day on Wednesday.
How the upper level pattern evolves beyond mid-next week is still
uncertain but will leave the slight chance PoPs of the NBM for
the late week timeframe. Temperatures will be much more pleasant
behind the cold front Wednesday into the weekend with highs in
the 70s to low 80s.

&&

.AVIATION /18Z TAFS THROUGH 18Z SATURDAY/...
Issued at 1240 PM CDT Fri Jul 11 2025

MVFR conditions at issuance should finally give way to VFR
conditions this afternoon. However, concern then turns to
potential for showers and thunderstorms this afternoon into
tonight, particularly southeast of a MCW-BCK line. At this time,
thunder looks to remain southeast of the terminals, but there is
a small (30%) chance for this to affect LSE, so have maintained
the PROB30 there. Abundant moisture should lead to a recurrence
of the IFR/MVFR stratus tonight with a higher probability of IFR
at RST. Confidence was not yet there to introduce IFR, so have
included low end MVFR instead to begin to trend the forecast
toward IFR.

&&

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

&&

$$

DISCUSSION...Barendse
AVIATION...Ferguson