550
FXUS63 KARX 080841
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
341 AM CDT Tue Sep 8 2026

.KEY MESSAGES...

- Ongoing showers and storms shift east through the morning
  hours, reinvigorating this evening into tonight. Rainfall
  amounts of around 1/2" to 1" are expected with locally higher
  amounts possible. Some strong to severe storms possible
  locally in northeast Iowa with damaging winds as the main
  threat.

- Additional precipitation potential (30-60%) for late Friday
  and into Saturday.

- Near normal temperatures are expected throughout the week with
  a possible cool down by late in the weekend.

&&

.DISCUSSION...
Issued at 334 AM CDT Tue Sep 8 2026

Morning Showers and Storms:

A line of showers and thunderstorms seen moving east across
Minnesota into North Central Wisconsin on RADAR imagery will
continue to develop along the nose of the low level jet as it
drifts east through the Upper Midwest. As these storms start to
move in later this morning, a few of these could be marginally
string to severe. There will be some elevated instability on the
order of 500-1000 J/kg to tap into with 25-35 kts of cloud
layer shear. The strongest cores may be able to produce some
marginally severe hail and a few strong wind gusts.

Additional Storm Potential Today:

Activity is expected to dwindle into the late morning/afternoon
as the low level jet weakens and veers with time and low level
forcing becomes a bit more nebulous across the region. Southerly
return flow and a fairly stout axis of 850 mb moisture
transport will continue to push into the region, allowing for
pWats to climb upwards of 2 inches by the afternoon. As
afternoon turns into evening, upper level support looks to
improve slightly with a shortwave impulse moving through the
building jet on the lee side of the trough axis. A reinvigoration
of showers and storms along and ahead of the cold front is
expected, again on the zone of a building low level jet. This
should mainly be south of the Minnesota state line in Iowa and
Wisconsin.

A low, albeit slightly higher than the morning storms, potential
(5-15%) for strong to severe storms with this activity as
instability will be weak (no more than 1000 J/kg) with generally
less than 30 kts of effective shear across the region. DCAPE
values between 750-900 J/kg results in strong/damaging wind
gusts as the main severe concern within the strongest cores.

The overall progressive nature of the front across our area
should limit the flooding threat but some higher totals may be
possible for our Northeast Iowa counties as the front looks to
have a bit slower forward motion there so storms may train a
little longer. The HREF 07.12 and NBM 08.01 show vastly
different stories as to probabilities for 1 inch of rain with
the latter being much more bullish on precipitation (as it has
been for the last couple of days). Given the pWats, the warm
cloud depths, and overall favorable warm rain processes, would
tend to lean more with the NBM on this occasion but much will
depend on the overall coverage of storms in the evening. The
front will continue to push through during the overnight hours
with most outside of far Southwest Wisconsin seeing dry
conditions by 12Z Wednesday.

Wednesday - Thursday: Drying Out, Near Normal Temperatures

As the front pushes through the area, a noticeably drier airmass
will follow in its wake. A weak high surface high will drop into the
Western Great Lakes region and help keep the area dry for the mid to
late week timeframe. In the upper levels, zonal flow to weak ridging
will prevail so while a "cold front" will have moved through,
temperatures will still be near normal in the 70s to low 80s. That
being said, the decreased humidity should make somewhat of a
difference.

Friday - This Weekend: Rain Chances Return, Cooler Temps?

Moving towards the weekend, yet another upper trough looks to dig
into the Upper Midwest, bringing with it another potential round of
precipitation Friday night into Saturday. The 07.12 LREF Grand
ensemble (GEFS/EC/GEPS) is already enthused about the potential for
precipitation with probabilities in the 50-70% range for Friday
night into Saturday. Given the upper trough and likelihood of a
trailing cold front to be moving through around that time, along
with strong return flow during the day on Friday, the chances for
rain are looking pretty strong to start the weekend. Temperatures
also look to take a bit of a hit as we potentially move into
zonal/weakly northwest flow aloft. By Sunday, high temperatures may
only be in the upper 60s to low 70s - much more reminiscent of the
supposed meteorological fall we`re in currently. The cooler
temperatures could linger into mid next week as yet another system
brings more modest chances for rain but there`s still much that
could change in regards to that this far out so will continue with
the blended forecast solution at this time.

&&

.AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/...
Issued at 1254 AM CDT Tue Sep 8 2026

Immediate impact of LLWS expected to progress east over the next
couple of hours with frontal boundary passage. Subsequent storm
impacts continue through the overnight and early Tuesday morning
hours, temporarily abating through the early afternoon before
returning through the evening.

&&

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

&&

$$

DISCUSSION...Barendse
AVIATION...JAR