542
FXUS63 KARX 031828
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
128 PM CDT Sun Aug 3 2025

.KEY MESSAGES...

- Ongoing smoke concerns primarily in Wisconsin through Monday.

- Gradual warming through the week with 90 degree isotherm
  returning by the end of the week.

- Precipitation chances increase Wednesday night primarily for
  western half of the forecast area from southeast Minnesota
  into central Wisconsin.

&&

.DISCUSSION...
Issued at 1247 PM CDT Sun Aug 3 2025

Smoke Concerns Today Through Monday:

Near surface smoke remains a concern through Monday primarily
for the eastern half of the forecast area in western Wisconsin as
east winds sustain the ongoing higher concentrations seen
through New England. Locally abutting airmasses result in a
sharp east-west gradient, potentially requiring further
refinement in headlines in coming forecasts. Concerns may
continue through Tuesday as little progression in overall
pattern keeps mostly east winds through Monday night.

Synoptic Pattern Through Midweek:

Upper level muddled cyclonic flow over the Central Plains on
afternoon GOES WV imagery, embedded within synoptic
anticyclonic flow into northern Canada, progresses southeast
tonight resulting in reamplification of the synoptic ridge
through the Northern Plains through Monday. Behavior of this
anomalous ridge, 90th percentile 500mb heights at Fort Smith,
Northwest Territories 03.12Z RAOBs according to SPC Climatology,
will be main driver of sensible weather impacts to the Upper
Mississippi River Valley.

Precipitation Chances Through Midweek:

Perturbations within rebounding upper level heights provide low
precipitation chances through the Upper Midwest Monday,
primarily west of the local forecast area where increased return
flow has provided more moisture (GOES, POES, RAOBs).

The anomalous (SPC climatology @ Churchill, MB) ridge axis
situates itself over the Upper Mississippi River Valley through
Canada Tuesday morning (LREF prob 500mb heights >580dam),
keeping strongest return flow upstream into the Northern Plains.
An initial perturbation lifting along the ridge`s upstream
flank through Tuesday night through Wednesday attempts to bring
initial precipitation chances locally; ultimately abated by
lack of forcing or moisture penetrating far enough east.
Confidence increases through Wednesday night as southwest flow
envelops the Upper Mississippi River Valley. Highest shear and
instability expected to lie closer to the Missouri River Valley
decreasing overall stronger storm threat concern locally. Will
be subsequent time frame to remain cognizant of however.

Gradual Warming Through The Week:

Return flow gradually strengthens through the week, increasing
local temperatures by a couple of degrees each day. Confidence
in the 90 degree isotherm remains through the Northern Plains
Thursday, shunting east towards the forecast area for Friday.

&&

.AVIATION /18Z TAFS THROUGH 18Z MONDAY/...
Issued at 1222 PM CDT Sun Aug 3 2025

VFR expected for most of the local forecast area from northeast
Iowa, southeast Minnesota, and western into central Wisconsin through
the 03.18Z TAF period; Wisconsin River Valley will likely see
VLIFR fog tonight into early Monday morning and IFR/LIFR fog
possible in central Wisconsin tonight into early Monday morning.

Low confidence (<20%) for fog impacts at KLSE TAF site tonight
into Monday morning due to increasing cloud cover from lingering
light precipitation over the Missouri River Valley today.

Expect wildfire smoke to remain through Monday although not
cause widespread impacts. Can`t rule out temporary MVFR
visibilities primarily in Wisconsin through Monday.

Moderate confidence (50-70%) for VFR through midweek. Low
precipitation chances Wednesday night into Thursday morning.
Low confidence in cloud cover limits confidence in river valley
fog impacts through midweek.

&&

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

&&

$$

DISCUSSION...JAR
AVIATION...JAR