355
FXUS63 KARX 161000
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
500 AM CDT Mon Jun 16 2025

.KEY MESSAGES...

- Strong to severe storms this evening and tonight. Highest
  confidence west of the Mississippi River Valley, primary
  hazards of damaging wind and large hail.

- Additional storm chances Tuesday through Wednesday and early
  Friday into Saturday morning.

- Warm weekend on tap.

&&

.DISCUSSION...
Issued at 146 AM CDT Mon Jun 16 2025

Main forecast concern continues to be severe storm threat later
today. Ongoing convection early this morning will help determine
timing of local severe threat later today. A couple recent HRRR
runs (16.02Z, 01Z, 00Z) exhibited an earlier QLCS affecting the
forecast area this afternoon-evening resultant of a decrease in
morning convection. The decrease allows an unstable airmass to
build locally, better fueling the storm potential. This scenario
will also be dependent on exact location of frontal boundary
causing cyclogenesis across the forecast area. While this isn`t
the highest confidence scenario, it could be the most severe
scenario and therefore something to monitor.

Highest Storm Confidence This Evening - Tonight:

Aligned with previous forecasts, highest confidence in a later
solution into the nighttime hours as the main low lifts
northeast through northern Minnesota; slowly draping a west-
southwest oriented frontal boundary southeast through the
forecast area. Given the later timing, the highest severe
threat would be farther west concurrent with peak diurnal
heating and more unstable air; aligning with Enhanced Risk in
SPC convective outlooks. Slight risk seen over locally western
counties in northeast Iowa and southeast Minnesota. Speed and
timing of convection will directly affect potential changes to
these risk locations; i.e., earlier = farther east.

Hazards & Accompanying Timing Impacts:

While clouded by location and timing of mesoscale forcing,
ample severe parameters (CAPE/Shear) await convection. With
this earlier solution, the most recent F48 HRRR (16.00Z)
increased 0-6km shear from 30 to 40 kts. While all high
resolution members suggest increase in shear over previous runs,
most limit it postfrontally or in minuscule spots of mesoscale
influence. Accompanying long hodographs suggest large hail will
be possible and damaging wind with increased low level flow.

Overall tornado threat is quite conditional on /if/ the earlier
QLCS takes shape. The earlier solution in the aforementioned
HRRR runs would increase this possibility while previous runs
and other models with a later solution limit overall surface
based activity.

Subsequent Storm Threat Tuesday:

Subsequent strong storm threat expected to affect the local
forecast area Tuesday, Tuesday night, and/or Wednesday morning.
Unfortunately confidence is low due to today/tonight`s storm
timing and resultant frontal location. The earliest solution
(lowest confidence) would result from a strong, linear storm
mode tonight, allowing instability to build farther north
through Tuesday. Current confidence keeps frontal boundary to
the south, advecting highest storm chances zonally along
southern half of the forecast area.

Storm Chances Wednesday:

Furthermore, the exit of tonight`s low affects subsequent
synoptic solutions for Wednesday. A surface low expected to
lift northeast along a southwest-northeast oriented baroclinic
boundary from the Southern to Central Plains; advecting the
lingering frontal boundary north across the forecast area. LREF
solutions which have exhibited slight variations over the last
couple of runs: agreeing on a slightly slower solution through
Wednesday morning, potentially providing some more unstable air
farther north. Although, the EPS has strengthened the low while
the GEFS has weakened, going to show the copious details requiring
ironing out. Regardless, better shear will lie postfrontally to
the north.

Storm Chances Friday Into Saturday:

Eventually mid level heights build (LREF 100% confidence) through
Thursday, reducing widespread precipitation potential into the
weekend. Precipitation potential will graze northern peripheral
counties in central Wisconsin as a low advects zonally along
the International Border Friday into Saturday.

Warming Through The Weekend:

Building heights through the end of the week (LREF 100%
confidence) increases surface temperatures through the weekend.
The warmest solutions seen in the EPS and GEPS with 60-100%
confidence for the 80 degree isotherm enveloping the forecast
area Friday warming into the upper 80s through the weekend. The
GEFS on the other hand suggests a colder solution with 10-30%
for 80 degrees on Friday and low 80s through the weekend. Will
be dependent on the strength and western extent of the Bermuda
High.

&&

.AVIATION /12Z TAFS THROUGH 12Z TUESDAY/...
Issued at 500 AM CDT Mon Jun 16 2025

Challenging forecast with a variety of synoptic, meso and micro
scale features that will all have roles to play in clouds and
shra/ts production through tonight. Short term guidance having a
very tough time in capturing the smaller scale features and can flip
hour to hour in their predictive outcomes. Forecast confidence high
that the region will see bouts of shra/ts through tonight. As for
timing/location questions...confidence is lower. Will continue to
paint with a broad brush, trying to highlight more likely outcomes
based more on the synoptics and/or ongoing trends. There will be
adjustments to cig and pcpn trends through the day as meso scale
interactions become more evident.

All said, going to lean into a VFR cig forecast into tonight with
MVFR favored for a few hours moving into the overnight. Scattered to
areas of showers/storms early this morning, with more shra/ts lined
up along a cold front later this evening. Can`t rule out spotty
convection for the afternoon.

&&

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

&&

$$

DISCUSSION...JAR
AVIATION...Rieck