495
FXUS63 KARX 190535
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
1235 AM CDT Sat Sep 19 2026

.KEY MESSAGES...

- Moderate to heavy rain is expected overnight. Still expect
  broad totals of 1-3" for much of the local area with localized
  higher amounts of 4-6". Flash flooding and rivers rising into
  flood stage may occur where these heaviest amounts fall -
  these higher amounts are expected to focus near an arc from
  Austin to La Crosse to Richland Center. A Flood Watch is in
  effect for much of the area south of I-94 to address this
  flooding potential.

- An additional round of storms is likely (60-80% chance) in
  far southwest WI and adjacent portions of northeast IA on
  Saturday afternoon/evening. Locally heavy rainfall may occur
  with these storms which would result in additional flooding
  potential.

- Rain chances (20-40%) persist through Monday before trending
  drier for the remainder of the upcoming week with cooler than
  normal temperatures expected.

&&

.DISCUSSION...
Issued at 1212 AM CDT Sat Sep 19 2026

Heavy rain overnight

Axis of showers and thunderstorms with rain rates up to 2" per hour
has developed in the vicinity of an 850/700mb front as increasing
moisture transport interacted with this front and around 1000 J/kg
of elevated instability helped generate stronger updrafts compared
with the showers earlier Friday. Observations of around 2-5" have
been seen in northern Fillmore and northern Mower Counties under
this band. Additionally, an area of scattered showers and storms is
seen around Mason City ahead of a disturbance located over north
central IA as of 03z. If current observational trends hold, areas
from Austin MN to La Crosse to Richland Center will see the heavy
amounts, potentially around 6".

Additional heavy rain possible Saturday afternoon

As a shortwave currently over western Nebraska ejects eastward and
lower level moist advection continues, short window with far
southwest Wisconsin and adjacent parts of northeast Iowa to be south
of the surface front. Thus, as the Nebraska shortwave approaches,
additional showers and thunderstorms will likely (60-80%) develop
there. With PWATs still near 2", efficient rain rates are once again
favored. Of particular concern is the potential for this round of
rain to overlap with where heavy rain occurs overnight Friday night.
Should this occur, flooding concerns would be heightened.
Finally, while highly unlikely given the tendency for
temperature profiles to be moist adiabatic, the window with
surface-based thunderstorms introduces a risk (1%) for a stray
tornado as sfc-500m helicity values look to reach close to 100
m2/s2.

&&

.AVIATION /06Z TAFS THROUGH 06Z SUNDAY/...
Issued at 1150 PM CDT Fri Sep 18 2026

IFR or lower conditions are forecast for the next 24 hours at
the terminals. Rain showers and occasional thunderstorms will
occur, with the best chance for thunderstorms continuing through
approximately 10-12z. Rain shower chances will continue through
the rest of the day, with the higher chances at KLSE. Have
maintained TEMPO groups for storms at KRST/KLSE. IFR to LIFR
ceilings will continue through at least Sunday morning. The wind
will initially be out of the east but will become more northerly
throughout this TAF cycle.

&&

.HYDROLOGY...
Issued at 1212 AM CDT Sat Sep 19 2026

Ongoing heavy rain from near Albert Lea to Viroqua has led to
flash flooding across portions of Mower, Fillmore, and Houston
Counties. The thunderstorms responsible for this flooding
continue to roll eastward and the axis is now slowly
propagating southward. In any case, rain rates from these
thunderstorms are not expected to let up as the atmosphere
remains anomalously moist. Flash flooding issues will continue
to be possible overnight with river rises expected to focus on
the Root and Kickapoo basins.

Moving ahead to Saturday, likely (60-80%) second round of heavy
thunderstorm looks to occur in far southwest Wisconsin and
adjacent parts of northeast Iowa. Additional flash flooding and
rises on streams and creeks would occur if these thunderstorms
develop with heightened concerns if they overlap areas that
receive multiple inches of rain early Saturday morning. Will
monitor closely overnight as heavy rain early Saturday may
impact Crawford/Richland/northern Grant Counties, locations
that will likely see those afternoon/evening thunderstorms.

&&

.ARX WATCHES/WARNINGS/ADVISORIES...
WI...Flood Watch through this afternoon for WIZ032>034-041>044-
     053>055-061.
MN...Flood Watch through this afternoon for MNZ079-086>088-094>096.
IA...Flood Watch through this afternoon for IAZ008>011-018-019-029-
     030.

&&

$$

DISCUSSION...Ferguson
AVIATION...Muscha
HYDROLOGY...Ferguson