117
FXUS63 KARX 102342
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
642 PM CDT Wed Sep 10 2025

.KEY MESSAGES...

- Warming through the weekend into the start of the new week with
highs topping 80 degrees for most. Saturday looking like the warmest
of the bunch.

&&

.DISCUSSION...
Issued at 130 PM CDT Wed Sep 10 2025

WEEKEND INTO NEXT WEEK: unseasonably warm weekend still on tap with
highs of 80+ degrees for many/most. Summery warmth continues for
start of the new week, looking to moderate toward seasonable norms
by the following weekend. Smattering of rain chances.

> OVERVIEW: Upper level ridge still on track to build eastward from
the plains to across the upper mississippi river valley this
weekend. West coast trough lifts northeast over the southern rockies
during this time, spinning bits of shortwave energy northeast. Both
the ridge and trough aren`t particularly strong, with the ensemble
guidance trending toward weakening both features as the weekend
wears on. That said, unseasonably warm air still on tap to pool
under the ridge. Whether or not the ridge will deflect any bits of
upper level energy west/north of the local area, and associated pcpn
chances, isn`t as clear.

Moving into the start of the new week, WPC clusters hang on to weak
upper level ridging across the western great lakes with weak
troughing across the northern plains/southern rockies. Gradually the
clusters shift toward more of a zonal flow for the latter half of
the week. How quickly this flow shifts and strength, positioning of
the relative features remains nebulous - keeping forecast confidence
and predictability low. If realized though, the change would
moderate temps downward to seasonable levels and also bring periodic
shots for rain.

> TEMPS: warmth, summery airmass set to pool northward under the
ridge as we move into the weekend. NAFES and ECMWF 850 mb temps
anomalies around +1.5 through the period with EFIs for high temps
Sat/Sun of 0.6-0.8 across NE IA/SW WI. Non-zero SoT touches these
locations. The GEFS has been showing a model bias with over warming
when soils are dry - which translated into the model blend and
required some adjustments (cooler). However, recent runs of the EPS
have nudged temps "up". Likelihood in the GEFS and EPS for 80+
degree highs Sat/Sun are now very similar from 1-94 southward -
roughly 60-80%. Additionally, the max temp in the EPS for KLSE is 90
Sat/Sun, just a couple degrees cooler than the GEFS. So models are
in more agreement. GEFS likely still too warm, but not completely
out to lunch either - at least locally. Will hold closer to the
model blend with all this in mind (may still shave off a degree or
two to coordinate with surrounding offices).

Transitioning into the 2nd half of next week, if WPC cluster trends
hold, a more zonal upper level flow would moderate temps toward the
seasonable norms.


> RAIN CHANCES: medium/long range guidance continues to suggest the
ridge won`t be a hard deterrent to shortwave activity, with any bits
of upper level energy able to shift across it rather than deflect
northward. Low end rain chances (20-40%) could work into the local
forecast area this weekend as a result.

Moving into next week, with general expectations to transition to a
quicker, zonal flow...shortwave activity could be more...active.
With variability within the models the model blend splatters low end
chances (20-40%) here and there. Again, with predictability low will
hold with the blend for now.

&&

.AVIATION /00Z TAFS THROUGH 00Z FRIDAY/...
Issued at 642 PM CDT Wed Sep 10 2025

VFR conditions continue through the evening and early
overnight hours. With light surface winds and clearing skies fog
moves into central Wisconsin and then southeast Minnesota,
southwest Wisconsin, and portions of northeast Iowa between 07Z
and 10Z. This fog may be locally dense at times. Have added a
tempo group for both KRST and KLSE for IFR visibilities as this
could be the case for much of the area. The fog is then expected
to dissipate between 13Z and 15Z and some CIGS around 5kft and
25kft move in for the afternoon. Light and variable winds
expected through the overnight then shifting to a predominant
light southeast wind for Thursday.

&&

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

&&

$$

DISCUSSION...Rieck
AVIATION...Cecava