168
FXUS63 KARX 290939
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
439 AM CDT Sun Jun 29 2025

.KEY MESSAGES...

- A few showers and storms linger this morning with scattered
  thunderstorms (40-50% coverage) redeveloping in the afternoon
  and evening, some of which could near severe levels.

- Additional threat for storms Monday and midweek, but
  confidence is low (20-30%) in the coverage and impacts from
  these storms.

- Warm today with seasonal temperatures for the start of the
  week, slowly warming again towards the end of the week.

&&

.DISCUSSION...
Issued at 140 AM CDT Sun Jun 29 2025

Today/Tonight: Storm Details

Ongoing linear convection across Minnesota is gradually winding
down early this morning as it starts to shift out of favored
deep shear regime, resulting in the storms becoming outflow
dominant. Nevertheless, forecast profiles from the HRRR/RAP
denote large values of MUCAPE overnight with relatively low
inhibition values for parcels launched around 800 mb as far
east as western Wisconsin. If the outflow boundary manages to
break this cap, we could see renewed development and the
potential for gusty winds and small hail, but complex
hodographs limit the organization potential for any individual
updraft.

The outflow and convective debris left over from our overnight
convection (surprise!) results in degraded confidence in how and
where convective initiation unfolds later today. What
constitutes a surface cold front (more of a broad wind shift vs.
a true front) migrates towards the region this afternoon from
the Dakotas. This front will be approaching the region towards
the mid to late afternoon, with convection likely initiating
both along the boundary and ahead of it in any leftover
differential heating zones courtesy of our morning storms. This
makes it very difficult to pin down the exact placement of
convection at any given time, though upscale growth into some
cell clusters is anticipated given the complex hodograph
profiles. As the surface front finally moves through in the
evening/overnight, we may see enough lift to keep some showers
and storms going through the night, mainly south of I-90.

The severe potential for this afternoon rests on robust but
short-lived updrafts getting strong enough to support brief
periods of low end severe wind (60 mph) or hail (around 1" in
diameter). Despite MLCAPE values nearing 2000 J/kg, the
aforementioned complex and compact hodographs will limit the
longevity of the updrafts and result in storms quickly getting
undercut by their own outflow. As we move through the evening
and night, the severe threat wanes with the increasing in
boundary layer stabilization.

Upcoming Week: Periodic, Low Confidence Risk of Storms

While there are multiple periods of storms in the forecast for
the upcoming week, the overall pattern is much drier than what
we saw last week. For Monday, a sharpening upper tropospheric
trough digs south into Minnesota, with there being enough
kinematic support and steepening low-level lapse rates to
support at least some convection--though the strength of the
cells remains in question given some signal for poorer mid-
level lapse rates stunting the vertical growth of the updrafts.
Tuesday should see a break in the storms as shortwave ridging
passes through. For midweek and into the end of the week,
northwesterly flow downstream of a meridional High Plains ridge
results in low confidence chances for convection, the details
of which are difficult to resolve at this range.

After another warm day today, cooler air settles in for the
start of the week and keeps temperatures near seasonal norms. As
return flow increases for mid to late week, increasing lower
tropospheric theta-e air will boost temperatures and dewpoints
back into the warm and muggy realm.

&&

.AVIATION /12Z TAFS THROUGH 12Z MONDAY/...
Issued at 440 AM CDT Sun Jun 29 2025

Predominantly VFR conditions are forecast for the TAF period
outside of localized pockets of restrictions within scattered
showers and thunderstorms from the mid-afternoon into the
early evening. These storms could produce locally strong winds
upwards of 40+ kts. Southerly winds early this morning veer to
the southwest during the day at around 10 kts before becoming
light from the west in the evening.

&&

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

&&

$$

DISCUSSION...Skow
AVIATION...Skow