Volney, Iowa Weather Forecast Discussion

521
FXUS63 KARX 091836
AFDARX
Area Forecast Discussion
National Weather Service La Crosse WI
135 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 /18Z TAFS THROUGH 18Z WEDNESDAY/...
Issued at 1235 PM CDT Tue Sep 9 2025
Primary concerns over the next 24 hours is potential for showers and
thunderstorms over the first 18 hours of the period, primarily 18-
06z. So far, intensity of rain itself to our west has not led to
MVFR visibility restrictions, leaving the timing of TS the chief
concern of the two. Unfortunately, a good deal of uncertainty in
timing remains so have gone with an extended PROB30 at RST for this
afternoon and early evening. In the southeastern two thirds of the
forecast area, instability and thus TS look to be less likely, so
have gone with a TS free forecast at LSE for now. Moving ahead, some
chance for fog north of an RST-BCK line overnight but confidence
this will spread south to RST/LSE is low.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
IA...None.
&&
$$
DISCUSSION...Rieck
AVIATION...Ferguson

NWS ARX Office Area Forecast Discussion