171
FXUS63 KARX 040416
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
1115 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 /06Z TAFS THROUGH 06Z TUESDAY/...
Issued at 1115 PM CDT Sun Aug 3 2025

CIGS: sct-bkn mid to high level clouds (generally 6-8+ kft) through
the period.

WX/vsby: another good setup for river valley fog - but the scattered
to broken nature of the clouds will work against it. Where it clears
- fog. Where it`s more cloudy, not so much. Will keep KLSE free of a
fog mention for now, but monitor satellite trends closely.

Smoke still around, but generally continues to improve. Don`t expect
vsby impacts at this time.

WINDS: southeast under 10 kts.

&&

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

&&

$$

DISCUSSION...JAR
AVIATION...Rieck