433
FXUS63 KARX 172341
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
641 PM CDT Sun May 17 2026

.KEY MESSAGES...

- Severe weather possible between 7 PM and 1 AM tonight. All
  hazards are possible mainly west of the Mississippi River.

- Another round of severe weather possible on Monday night
  between 9 PM and 4 AM. The main threat will be damaging winds.
  With isolated threats of hail and maybe a few QLCS tornadoes.

&&

.DISCUSSION...
Issued at 1257 PM CDT Sun May 17 2026

This Afternoon

The remnant MCV which brought rain mainly south of Interstate 94
will continue to move northeast away from the area this afternoon.
As it does, the showers and isolated storms currently along
Interstates 90 and 94 will move east northeast away from the area.
Additional rainfall amounts will be up to a half inch. As a warm
front gradually lifts northward, temperatures along and south of
Interstate 94 will warm into the 60s and lower 70s, and into 60s
north of this Interstate. This will result in surface-based CAPES
climbing into the 1000 to 2500 J/kg along and south of Interstate 90
by 7 pm.

Tonight

Late this afternoon and evening, 2-3K J/kg CAPES will develop ahead
of a squall line moving east across eastern South Dakota, eastern
Nebraska, northern Iowa, and southern Minnesota. with 0-6 km
shear approaching 40 knots, there could potentially be some
supercells located along the line (these would likely stay
west of the Upper Mississippi River Vally) and along the warm
front near the Minnesota and Iowa boarder. In addition to the
deep shear, there is 200-300 EHI along the Minnesota and Iowa
boarder and downdraft CAPEs up to 1K J/kg. The discrete
supercells ahead of the squall line would be capable of
producing wet microbursts, large hail, and isolated tornadoes
between 7 PM and 10 PM in southeast Minnesota and northeast
Iowa. The threat will then shift to more damaging winds and
maybe a few QLCS tornadoes as the squall line moves into
southeast Minnesota and northeast Iowa between 10 PM and 11 PM.
This line will then gradually weaken as the instability wanes.
The severe weather threat will likely wane by 1 AM Monday.

Monday night

A cold front will move east through the area. There will be 1-2K
J/kg CAPES ahead of this front. With much of the deep (0-6 km) shear
located post frontal, not anticipating any supercells. As a result,
if there is severe weather, it would be located along the cold front
as a squall line. The primary threat would be damaging winds with
secondary threats as hail and QLCS tornadoes. Timing looks to be
rather similar tonight with the squall line moving into northeast
Iowa and southeast Minnesota between 9 PM and 10 PM. It will exit
the area between 2 AM and 4 AM. By this time, the winds will likely
be sub-severe.

Friday into Saturday

A shortwave trough will move east through the area. This will result
in another round of showers and isolated storms. With CAPES less
than 250 J/kg and 0-3 km and 0-6 km shear less than 25 knots, not
anticipating any organized severe weather at this time.

&&

.AVIATION /00Z TAFS THROUGH 00Z TUESDAY/...
Issued at 636 PM CDT Sun May 17 2026

MVFR to IFR conditions currently present across the region with
some isolated instances of LIFR along and south of the I-90
corridor. Low clouds are expected to linger for most areas
through later tonight with some low precip chances. The main
chance for storms looks to push east into the region late this
evening - likely between 04-08Z for the terminals. The main
threat with this line of storms will be strong winds and heavy
rainfall so have continued with the TEMPO groups that bring
stronger winds in for a short time period. Lower rain chances
will continue into tomorrow morning behind the line of storms
with most locations lifting back to VFR CIGs through the
morning. Some lower MVFR/IFR CIGs may linger across portions of
SE Minnesota and WC Wisconsin so have kept them at the KRST
terminal through the end of the period.

&&

.HYDROLOGY...
Issued at 106 AM CDT Sun May 17 2026

One to two inch totals are still forecast across the area, with
areas further west more favored for the 2 inch totals. This will
likely not cause river flooding, only within bank rises.

&&

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

&&

$$

DISCUSSION...Boyne
AVIATION...Barendse
HYDROLOGY...Baumgardt