317
FXUS63 KARX 120744
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
244 AM CDT Thu Jun 12 2025

.KEY MESSAGES...

- Flooding threat has greatly lowered due to the greater
  instability remaining over southern and western Iowa through
  Friday and easterly winds advecting drier air into the region
  tonight. Rainfall amounts from last night through Friday night
  will be up to a half-inch in central Wisconsin and range from
  a half to 2 inches elsewhere across the Upper Mississippi
  River Valley.

- Periodic showers and storms expected next week.

&&

.DISCUSSION...
Issued at 243 AM CDT Thu Jun 12 2025

This Morning

Showers and storms are continuing to develop along north of a
surface front near Interstate 80. Most unstable CAPES are up to
500 J/kg across northeast and north-central Iowa and between 500
and 1000 J/kg just south in central Iowa and the effective
shear is up to 35 knots in north-central Iowa. With downdraft
CAPES up to 1300 J/kg and inverted-V sounding, might see some
gusts up to 50 mph. The CAPE profile looks sufficient to produce
around 1-inch diameter hail. Within the next 2 to 4 hours, the
effective shear is forecast to fall below 25 knots and the deep
moisture convergence also weakens. As this occurs, this
convection is forecast to gradually weaken.

Further north, there is another band of showers and scattered
storms along the Minnesota/Iowa border. This band is associated
with moderate to strong 850 mb frontogenesis and weak to
moderate 850 mb moisture convergence. The CAMs continue to show
that this 850 mb frontogenesis will gradually shift north and
weaken. In addition with the low-level jet weakening and veering
this morning, the moisture convergence will weaken along this
front. As a result, this convection should gradually weaken and
become more scattered this morning.

This Afternoon

A stationary front will linger along the southern border of the
forecast area. Most unstable CAPES will be up 1500 J/kg in
northeast Iowa. Surface-based storms will initially develop
along the front between 12.19z and 12.21z due to very steep
950-850 mb lapse rates and weak convergence. Sounding profiles
show winds aloft generally less than 15 knots and skinny CAPE
profiles. If severe storms happened to develop, they would be
short-lived. Main threats would be hail up to quarters and
gusty winds. As these storms move north in northeast Iowa, they
will quickly become elevated and weaken.

Further north, scattered convection will be found along and
north of the Interstate 90 corridor as the 850 front moves
slowly north.

This Evening

One new development in the CAMs is that east winds will advect
dry air (dew points in the mid- and upper 40s) into the region
from the Great Lakes. As a result, we have seen a reduction in
our rainfall amounts in the Upper Mississippi River Valley. At
this time, the heaviest rain (1.5 to 4 inches) looks to fall
from the northwest suburbs of the Twin Cities northwest into
central Minnesota.

Friday and Friday Night

A weak surface low and upper level shortwave trough will move
east across the area. While there will gradually recover into
the lower 60s in the warm sector of this system, low-level
convergence will be mainly found north of the warm front over
northern Wisconsin and along a cold front that will be moving
east through the Upper Mississippi River Valley.

Rainfall amounts from last night through Friday night will be up
to a half-inch in central Wisconsin and range from a half to
2 inches elsewhere across the Upper Mississippi River Valley.

Early and Mid Week Next Week

An upper-level ridge will build northward toward the region.
However, it looks like will stay southwest and south of the
Upper Mississippi River. There will be periodic threats of
showers and storms as shortwave troughs on the northern
periphery of this ridge move through the region.

&&

.AVIATION /06Z TAFS THROUGH 06Z FRIDAY/...
Issued at 1235 AM CDT Thu Jun 12 2025

As the 850 mb front moves north toward Interstate 90, showers
and scattered storms will spread into the TAF sites between
12.08z and 12.11z. These showers will then continue through the
morning and then come to an end as this 850 mb front moves north
toward Interstate 94.

Additional showers and storms will move into the area this
evening. With dry air advecting into the area from the east, the
probability for showers and storms looked lower for KLSE, so
only have PROB30 for them.

&&

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

&&

$$

DISCUSSION...Boyne
AVIATION...Boyne