371
FXUS63 KARX 281033
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
533 AM CDT Sat Jun 28 2025

.KEY MESSAGES...

- Showers and storms in south central Minnesota are moving
  eastward this morning, reaching areas west of the Mississippi
  River through daybreak (20-40%). Additional showers and storms
  possible this afternoon (20-30%).

- Strong to severe storms possible tonight, primarily north of
  I-90, but confidence in overall coverage and timing is low
  (10-20%).

- Higher confidence in strong to severe storm potential Sunday
  afternoon. The primary threat is damaging winds.

- Drier start to the new week. Showers and storms return by
  mid-week.

&&

.DISCUSSION...
Issued at 422 AM CDT Sat Jun 28 2025

Today

A line of showers/storms is moving eastward across south central
Minnesota this morning of which CAMs have been struggling to
resolve through much of the overnight. Most do indicate it
weakening before it reaches southeast Minnesota and northeast
Iowa as it should outrun the instability gradient it appears to
be associated with, which has been the trend over the last few
hours. However, areas west of the Mississippi River could see
some rain through daybreak.

Some patchy fog is noted this morning, primarily across western
Wisconsin, but should begin to dissipate after daybreak. Otherwise,
the trend of poor agreement amongst the CAMs leads to uncertainty in
how precipitation will trend through the rest of the day. A general
20-40% probability of showers/storms is expected across the
region based on the 28.00z HREF mean. However, the HRRR has
begun to suggest the remnant MCV associated with the storms
continues eastward into our area, initiating some new storms
capable of gusty winds and small hail this afternoon. Otherwise,
temperatures today climb into the mid to upper 80s for most,
upper 70s for those in north central Wisconsin with heat indices
in the low to mid 90s.

Strong to Severe Storms

Quite a bit of uncertainty in how tonight`s severe weather will
play out with low confidence in its evolution. As discussed in
the previous section, CAMs struggle to be congruent in their
solutions, but most indicate convective initiation along a
surface boundary situated across central Minnesota into north
central Wisconsin with shear and instability sufficient for
severe storms. The boundary slowly sinks southeast during the
afternoon and evening, but there`s disagreement in how far
south the convection makes it and when. If severe storms do make
it into our area, the primary hazards are damaging winds and
hail, but could see an isolated tornado along the boundary.

There`s a bit more clarity for Sunday with many of the CAMs
suggesting similar scenarios. A surface boundary moves southward
into the region as we head into the afternoon hours. Impressive
instability of 3000+ J/kg is progged to develop ahead of this
boundary as diurnal heating takes hold with CAM guidance
indicating convection fires along this boundary as it moves into
the more unstable environment. Fairly weak 0-6km bulk shear of
15-20kts is expected over the region and should be oriented
parallel to this boundary, indicative of a linear convective
mode. As such, the primary threat associated with these storms
is damaging winds, but some small hail is possible in more
discrete cells that are able to develop initially. Given the
0-3km shear vector is also oriented parallel to the boundary,
tornadoes are unlikely, but if there are sections that are able
to orient more normal to this vector, a brief spin up could be
possible.

Drier Start To The New Week

Upper level longwave ridging builds into the central United
States Monday and remains through much of the week. WPC cluster
analysis indicates this ridge will remain primarily to our
west, setting up northwest flow across the Upper Mississippi
River Valley. Shortwave ridging and surface high pressure are
expected to be in place across the Midwest Monday and Tuesday,
indicating a <10% probability for precipitation to start the new
week. Shortwave troughs are then expected to traverse the mean
flow by Wednesday with ensemble guidance depicting a 20-40%
probability of rain/storms each day to close out the week.

&&

.AVIATION /12Z TAFS THROUGH 12Z SUNDAY/...
Issued at 530 AM CDT Sat Jun 28 2025

Pockets of MVFR/low VFR stratus and IFR/LIFR fog east of the
Mississippi River lift early this morning with isolated VFR
showers moving through this morning. Additional showers and
storms may affect areas north of a RST to ISW line this evening
and overnight, but confidence is low in aviation impacts. Winds
today will be from the south at 10 to 15 kts, gusting up to 20
kts west of the Mississippi River, lessening to 5-10 kts
tonight.

&&

.ARX WATCHES/WARNINGS/ADVISORIES...
WI...Dense Fog Advisory until 9 AM CDT this morning for WIZ017.
MN...None.
IA...None.

&&

$$

DISCUSSION...Falkinham
AVIATION...Skow