Whittlesey, Wisconsin Weather Forecast Discussion

171
FXUS63 KARX 100456
AFDARX
Area Forecast Discussion
National Weather Service La Crosse WI
1156 PM CDT Tue Sep 9 2025
.KEY MESSAGES...
- Scattered shower/storms this afternoon/tonight - mostly across
parts of southeast MN/western WI
- Warming through the weekend, topping 80 degrees for highs for many
Fri-Sun.
&&
.DISCUSSION...
Issued at 135 PM CDT Tue Sep 9 2025
REST OF TODAY/TONIGHT: convection firing across southern MN/northern
IA in response to an upper level shortwave trough will continue to
shift east across the forecast area for the rest of the
afternoon/tonight. Low level jet picks up a bit by 00z, aiding the
lift. PWs as much as 1 1/2" but warm cloud depths generally under 3
kft - limiting any heavier rain risk to very localized.
Shower/storms also shifting away from the main instability pool -
working against stronger storms. Track of the shortwave positions
more of the areal coverage over SE MN/western WI - depicted by the
majority of the CAMS. Will follow suit.
A decrease overnight in areal coverage/intensity, but with the slow
movement east of the trough, at least some low end rain chances
(20%) will linger over western WI Wed morning.
THROUGH THE WEEKEND/EARLY NEXT WEEK:
> OVERVIEW: Upper level ridge builds across the region for the
weekend while west coast trough lifts northeast across the
rockies/northern plains. Neither feature is particularly "stout"
with long term guidance favoring a break down of the trough with
some weakening in the ridge. Warmer air will pool under the ridge,
making for a relatively "warm" for the season second half to this
week, but bits of upper level energy will spin out of the trough,
working across the ridge too. This will bring a smattering of rain
chances.
Some suggestions in the long range guidance for more zonal flow for
next week, but still weak without any signficiant troughing/ridging
on the horizon. WPC clusters show similar disinterest in sketching
out something more defined. Temps would moderate to the seasonable
norms in this scenario with a continued smattering of rain chances
here and there. Ensemble guidance variability and relatively weak
signals keep predictability and confidence low in the details.
> TEMPS: warmer air set to push northward under the encroaching
ridge as we move into the weekend. Long range guidance/ensemble
suites start pushing 80+ degree as soon as Thu, but more likely
Friday through the weekend. Sat currently shaping up to be the
warmest of the bunch with the grand ensemble painting 60-80% chances
for 80+ degree highs along/south of I-94 Sat, a bit less Sunday. If
the GEFS has its way, upper 80s to around 90 would be reached for a
few locations with 50% of its members favoring the hotter summer
warmth. Think the GEFS is suffering from a model bias and too warm
for this period - although a small subset of the EPS (10%) hint that
it could happen. For now, will stick with the model blend. North of
there a tad cooler but upper 70s/lower 80s still tracking.
Although how the upper level flow sets up for next week is not
clear, the generally trends would favor temps cooling back toward
the mid Sep norms.
> RAIN CHANCES: as mentioned, mostly weak signals via the long range
ensembles but all suggestive of persistent bits of upper level
energy spinning near/across the upper mississippi river valley.
Resulting rain chances, areal coverage and timing suffer from the
weak signals and ensemble differences. Will hold with the model
blend which paints a smattering of low end chance here and there.
Expect some refinement in these rain chances as we move through the
weekend.
&&
.AVIATION /06Z TAFS THROUGH 06Z THURSDAY/...
Issued at 1154 PM CDT Tue Sep 9 2025
VFR to MVFR conditions currently present across the region with
areas of light to moderate showers slowly pushing east/southeast
through the area. These showers will continue to move away from the
terminals and into Central/Eastern Wisconsin over the coming hours.
Behind these showers, areas of dense fog have begun to develop
across northern and central Minnesota. This is expected to fill
in behind the rain and could impact the RST terminal in the
coming hours. RST currently looks to be right on the edge of
where the dense fog will likely set up so have stuck with MVFR
visibilities and IFR CIGs for now though this may need to be
amended should the fog over-perform. LSE should stay clear of
the fog this morning and remain VFR. Winds will remain light
through the period becoming more northerly through the afternoon
hours.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
IA...None.
&&
$$
DISCUSSION...Rieck
AVIATION...Barendse

NWS ARX Office Area Forecast Discussion