134
FXUS63 KARX 151058
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
558 AM CDT Wed Oct 15 2025

.KEY MESSAGES...

- Precipitation chances linger across southwestern half of the
  local forecast area through today.

- High precipitation chances overnight into Thursday morning and
  Friday morning through Saturday morning.

- Warmer than normal temperatures Thursday and Friday with
  daytime highs in the 70s for some.

&&

.DISCUSSION...
Issued at 329 AM CDT Wed Oct 15 2025

Lingering Rainfall Chances Today:

A pool of anomalous (SPC climatology) moisture is situated over
the forecast area, from maximum percentile PWATs (DVN 15.00Z)
RAOB) bifurcating the southern half of the forecast area to 90th
percentile (GRB/MPX 15.00Z RAOBs) to the north. Expect this
boundary to linger through much of today due to flattening of
the upper level ridge periphery evident on GOES upper level
water vapor imagery loops, signifying weakening of meridional
moisture transport. An axis of dilatation situated between high
pressure centers north and south of the forecast area will perpetuate
precipitation chances where this increased moisture lies across
the southwestern half of the forecast area from southeast
Minnesota through northeast Iowa into far southwest Wisconsin.
Therefore, have increased PoPs through tonight in collaboration
with neighboring offices. While moisture remains anomalous, a
lack of strong forcing limits overall rainfall amounts near 0.5"
(HREF) with higher amounts near 1"+ possible in spots where
heavier rainfall rates temporarily occur according to HREF LPMM
and ensemble maximum.

Precipitation Chances Thursday

An upper level low lifting north over the Sierra Nevadas on
early morning GOES water vapor imagery will reinvigorate
meridional moisture transport later today, eventually forming a
strong Midwest Atmospheric River of 850-1000 kg m-1 s-1
integrated vapor transport overnight through Thursday. Current
trajectory places the anomalous moisture (3+ standardized model
climate anomalies in NAEFS/ENS) between the Missouri and
Mississippi River valleys, advecting as far north as central
Ontario (Moosoonee, ON RAOB per SPC climatology) in LREF PWAT
probabilities this weekend. LREF confidence limits highest
impacts well to the west of the forecast area into the northern
Plains with location of initial cyclogenesis resulting in ECMWF
extreme forecast QPF indices of 0.92 with a shift of tails of 2
from North Dakota into Montana on Friday. Local precipitation
chances, will lift northeast overnight through Thursday providing
another 0.5" through Thursday primarily along western half of
the forecast area, tied to the tightening surface pressure
gradient, accompanying forcing from resultant low level jet,
and stronger low level isentropic upglide. Higher amounts near
1"+ will be possible where scattered, heavier rainfall rates
repeat.

Precipitation Chances Friday & Saturday:

As the moist air exits northeast, a short reprieve in higher
precipitation chances is expected overnight Thursday into Friday
morning. Extent and duration of any drying remains unclear as
LREF members suggest cyclogenesis along lingering baroclinic
boundary although overall forcing remains questionable.
Subsequent upper level northwest flow (LREF) zonally advects the
upper level trough axis and accompanying surface front across
the Upper Midwest Friday through Saturday. Current confidence in
local impacts remains limited to heavy rain as SBCAPE/MUCAPE
values remain 150 to 300 J/kg (LREF). LREF confidence near 50% for
a widespread 0.25" to 0.5".

Warm

Eastern extent of main plume of excited return flow will determine
magnitude of anomalous temperatures Thursday with current
LREF/HREF/NBM confidence for the 90th percentile 70 degree
isotherm grazing our southwestern peripheral counties in
northeast Iowa and southeast Minnesota. More widespread
probabilities for the 70 degree isotherm for Friday as frontal
boundary advects east across the Upper Mississippi River Valley.
Maximum temperature records at La Crosse (84) and Rochester
(85) do not appear in jeopardy.

&&

.AVIATION /12Z TAFS THROUGH 12Z THURSDAY/...
Issued at 554 AM CDT Wed Oct 15 2025

Widespread flight rule restrictions are ongoing and expected to
continue over the next 24 hours. Many locations as of issuance
time are experiencing IFR/LIFR conditions due to light rain and
stratus. As rain probability tapers off this morning, expect
this to improve slightly through the day to mainly MVFR/IFR
conditions by around mid- afternoon. An additional round of rain
may occur after 06z but refrained from using PROB30 groups to
cover with this issuance since this falls outside the critical
TAF period.

&&

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

&&

$$

DISCUSSION...JAR
AVIATION...Ferguson