387
FXUS63 KARX 161049
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
549 AM CDT Sun Aug 16 2026

.KEY MESSAGES...

- Drier conditions are expected today into Monday with near-
  normal highs in the upper 70s to low 80s.

- Shower and storm potential returns Monday night into Tuesday morning
  (30-50%) and Tuesday afternoon into Wednesday (30-60%),
  though better chances have begun to trend southward.

- Periodic chances for showers and storms exist through the end
  of next week.

&&

.DISCUSSION...
Issued at 1245 AM CDT Sun Aug 16 2026

Today - Monday: Drier, Near Normal Temperatures

A weak cold front moving through the region overnight should shift
eastward by the mid-morning hours today. Some isolated to scattered
light showers are possible (20-40%) along the front overnight,
mainly north of I-94, where stronger convergence along said
front exists. Areas of patchy fog have also begun to develop
given the humid conditions in place, but will begin to dissipate
after sunrise through around 9am.

Dry conditions are then expected throughout the rest of the day as
drier air is ushered into the region associated with northwest winds
behind the front. Some slightly stronger wind gusts are expected
through the afternoon, generally 15-20mph given steepening 0-1km
lapse rates in response to some weak cold air advection. Benign
conditions continue into Monday as high pressure remains the
dominant feature across the Upper Midwest, though another surface
cold front begins to move southward into the region Monday night as
mid-upper level troughing across Canada deepens while warm
and moist southerly flow across the Central Plains noses northward.

Tuesday - Wednesday: Increasing Shower and Storm Potential

The aforementioned front continues moving southward overnight Monday
into Tuesday, leading to some precipitation potential as it does (30-
50%). Instability along the front will be lacking given the
overnight timeframe, though some elevated instability upwards of 500
J/Kg per 15.18z GFS soundings suggests a few rumbles of thunder
can`t be ruled out.

The front lays out generally west to east across northern Iowa into
southern Wisconsin Tuesday afternoon while another shortwave makes
its way across zonal upper level flow. Because of this frontal
placement, shower and storm potential has trended southward over the
past 24 hours. Dewpoints in the low to mid 60s look to pool to the
south of the boundary, greatest across northeast Iowa into southwest
Wisconsin allowing MLCAPE to build to 1500-2000 J/kg during the
afternoon. 500hPa flow begins to increase as well as a jet streak
associated with the aforementioned wave overspreads the area,
increasing 0-6km bulk shear to 35-45kts. While the primary
ingredients for strong to severe storms look to be in place for
those south of the boundary, some uncertainty regarding the
influence of morning shower/storm activity on the afternoon exists
as well as some potential timing issues between the strongest
instability and wind shear. Regardless, AI/ML guidance continues to
suggest severe convection is possible which is also reflected by the
SPC which currently highlights our southern counties as a favorable
area for severe weather. Will need to continue to watch for any
additional positional and temporal trends as these will influence
what areas will have the most favorable thermodynamic and kinematic
environment for strong to severe convection.

Outside of strong/severe potential, heavy rainfall looks to be
possible with storms that develop. Current probabilities in the
16.01z NBM suggest amounts around 1 inch are not out of the
question, generally 10-30%, though the expected placement of the
front and the southward trend previously discussed suggests the
highest amounts should remain across central Iowa.

Thursday - Next Weekend: Periodic Showers and Storms

Northwest upper level flow remains situated across the Upper Midwest
from the middle to the end of the new week, allowing several
shortwave impulses to move through the region. Periods of showers
and storms are possible in response to these upper level features
though variations amongst the ensemble members keeps probabilities
for said showers and storms on the lower side for a given day,
generally 10-30%.

&&

.AVIATION /12Z TAFS THROUGH 12Z MONDAY/...
Issued at 549 AM CDT Sun Aug 16 2026

MVFR to IFR conditions this morning will improve to VFR as
diurnal mixing works to increase cigs. Consequently, expecting
IFR/MVFR reductions at KLSE and KRST to increase to VFR by late
morning. Winds will remain from the northwest at around 8-12 kts
throughout the daytime hours before diminishing overnight.
Cannot rule out (10% chance) some valley fog at KLSE towards 12z
Monday. However, given the northwesterly surface wind direction
and a relatively shallow light wind layer in the recent RAP,
have opted to exclude any fog mention during this timeframe.

&&

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

&&

$$

DISCUSSION...Falkinham
AVIATION...Naylor