305
FXUS63 KARX 271938
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
238 PM CDT Fri Jun 27 2025

.KEY MESSAGES...

- Dense fog possible tonight.

- Several lines of storms will move through the area this
  weekend (Saturday morning, Saturday night, and Sunday
  afternoon and evening). The second and third lines may produce
  some damaging winds.

&&

.DISCUSSION...
Issued at 238 PM CDT Fri Jun 27 2025

This afternoon

A weak surface trough will move east across western Wisconsin
this afternoon. With surface-based CAPES up to 200 J/kg and
weak shear along and ahead of this boundary, only expecting
isolated to scattered showers and maybe an isolated storm or two.

Tonight

The ridge axis will be overhead. With light winds and clearing
skies, there will be the possibility of dense fog. Early this
morning, this ridge axis was located over the Northern Plains
and it produced dense fog there.

Saturday Morning

The CAMs are in general agreement that a weakening mesoscale
convective complex will southeast through the area. While there
is in agreement that this will likely occur, the timing is
uncertain ranging as early as 28.11z (NAM 4km) to 28.14z (HRRR).
ML CAPES will generally range from 250 to maybe 750 J/kg. With
this convective complex being linear, winds will be the primary
threat with this line. At this time, expecting wind gusts of
30-40 mph.

Saturday Afternoon and Night

With mostly to partly sunny skies, most unstable CAPES will
climb into the 1500 to 3000 J/kg during the afternoon. The 0-6
km hodographs are favorable for supercells across the eastern
Dakotas and west-central and southwest Minnesota during the mid
to late afternoon. As these cold pools coalesce, this convection
will become more linear and move southeast toward the area.
With this system moving into a less shear environment and the
MU CAPES weakening, there should be a gradual decrease in
intensity. SPC currently has a slight (threat level 2 out of 5)
risk across parts of southeast Minnesota and northeast Iowa. The
main threat would be damaging winds.

Sunday Afternoon and Night

A remnant outflow boundary will be located somewhere near the
Interstate 90 corridor. As surface heating develops, there
should be intensifying deformation heating band developing. The
models suggest weak convergence along this boundary and this
should result in the development of isolated to scattered
convection. With weak shear, not anticipating any severe
weather in our area. Meanwhile, further west additional showers
and storms are expected to develop along a cold front. As the
front moves east, the convergence will increase along this
front. A line of storms is expected to move through the Upper
Mississippi River Valley during the late afternoon and evening.
The main threat with this line will be damaging winds.

Wednesday through Thursday

An upper level ridge will build across the Central Plains and
possibly the Northern Plains. During the afternoons and
evenings, scattered supercells are expected to develop in the
Dakotas and then as their cold pools coalesce, this will result
in a forward propagating mesoscale convective complexes. The
main question is where these systems will track across the Upper
or Mid Mississippi River Valleys. The operational GFS and many
of its ensembles suggest these convective systems will track
southeast across the Upper Mississippi River Valley. Meanwhile,
the operational ECMWF continues to track these convective
systems will track across southwest Minnesota, and western and
southern Iowa.

&&

.AVIATION /18Z TAFS THROUGH 18Z SATURDAY/...
Issued at 108 PM CDT Fri Jun 27 2025

MVFR conditions improve to VFR later this afternoon and low-level
moisture decreases. VFR conditions persist through the evening,
however as a steep low-level inversion increases with light surface
winds, some fog development will be possible across portions of WI
and along the Mississippi River. As a result, have included a 3sm
group at KLSE for a few hours tomorrow morning. Otherwise, VFR cigs
are expected throughout the rest of the morning on Saturday with
some probability for a complex of decaying thunderstorms to sneak
into the region around 12-15z. There remains significant differences
between the CAMs on how this may evolve though so have not included
any mention in the TAF at this time.

&&

.HYDROLOGY...
Issued at 135 PM CDT Fri Jun 27 2025

An areal flood warning remains in effect along the La Crosse
River and its tributaries from just east of Sparta to La
Crosse. This was due to around 5 inches of rain this week. This
has resulted in moderate flooding. This flooding is expected to
continue into Sunday morning.

Minor flooding continues along the Cedar River in Austin and
Black River at Black River Falls. However, these rivers are
expected to fall below flood stage either late this afternoon or
early evening.

Minor flooding is expected to occur in the Charles City area by
Saturday evening.

&&

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

&&

$$

DISCUSSION...Boyne
AVIATION...Naylor
HYDROLOGY...Boyne