633
FXUS63 KARX 131045
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
545 AM CDT Sat Sep 13 2025

.KEY MESSAGES...

- A taste of summer warmth this weekend and into early next
  week, featuring highs in the 80s and muggy dewpoints. Cooler
  weather returns towards the end of next week.

- Periodic bouts of showers Sunday and through the start of the
  new week (20% chance), with the better shot of widespread
  showers and storms coming mid-week (30-50% chance).

&&

.DISCUSSION...
Issued at 335 AM CDT Sat Sep 13 2025

Return of Summertime Warmth!

The main story for the weekend and into early next week will be
the return of summertime heat. Mid-tropospheric warm air (+18-20
C) arrived yesterday with the surface warm front lifting to
around the MN/IA border early this morning. The recent global
and convective allowing guidance have backed off on the
northward progression of the warm front compared to yesterday at
this time, resulting in slightly cooler forecast temperatures.
However, we are still capable of mixing down the warmer air
aloft and no matter how you slice the forecast it will be an
unseasonably warm and muggy day with highs in the mid to upper
80s from western WI on west.

It isn`t until the upper tropospheric ridge axis passes to the
east on Sunday and into Monday that we see enough of a southerly
push to eject the warm front northward (possibly resulting in
our warmest temperatures of this stretch by Tuesday). Despite
the downstream ridge forming an Omega Block, there will be
enough erosion of the ridge`s western flank by a series of waves
to break it down by midweek. Before this breakdown, high
temperatures will be fairly consistent in the mid to upper 80s.
Following the ridge breakdown, this warmer air shunts to the
south and a more seasonal airmass takes its place. The exact
timing of this transition will depend on trends with upstream
convection Tuesday and Wednesday.


Mostly Dry through Early Next Week

A band of elevated showers and storms that brought a focused
corridor of 1-2+ inches of rain along the I-94 corridor
continues to wane early this morning and should depart by
sunrise. It is worth noting that we could see some light
sprinkles this morning based on some of the latest HRRR/RAP
soundings, but impacts will be very minor and transient given
the high cloud bases and deep layer of dry sub-cloud air to
overcome.

A negatively-tilted shortwave carving out the ridge over the
mid to upper Missouri River valley Sunday night into Monday
morning may be enough to force some light showers through the
region--mainly west of the Mississippi River. The better risk
for widespread showers comes midweek as the longwave ridge
begins to break down, with one or more thunderstorm clusters
working through during this period. The global models are still
resolving the characteristics of this wave and it is tough to
nail down specifics at this range in the forecast.

&&

.AVIATION /12Z TAFS THROUGH 12Z SUNDAY/...
Issued at 545 AM CDT Sat Sep 13 2025

Aside from a band of IFR/LIFR fog and low stratus in the wake
our overnight rain from EAU to DLL that should dissipate by
mid-morning, VFR conditions are forecast for the rest of the
day into the evening. Will need to continue to monitor the
potential for fog overnight, especially along and east of the
Mississippi River. Winds will be from the south to southeast at
around 5-10 kts for the TAF period.

&&

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

&&

$$

DISCUSSION...Skow
AVIATION...Skow