283
FXUS63 KFSD 071807
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
107 PM CDT Mon Sep 7 2026

.KEY MESSAGES...

- A couple of supercells will be possible west of the James
  River late this afternoon through early evening. IF a storm
  can develop, a tornado or two, ping pong ball sized hail and
  wind gusts to 70 mph are all possible.

- Additional scattered and possibly severe storms are possible
  from late evening into the early overnight hours. The main
  threats will be half dollar sized hail and wind gusts to 65
  mph.

- Quiet but continued warm conditions are expected for the rest
  of the work week with the next better chance for
  precipitation Saturday night into Sunday.


&&

.DISCUSSION...
Issued at 103 PM CDT Mon Sep 7 2026

Elevated showers and thunderstorms will continue to move
northeast through central SD into the afternoon. Locally heavy
rain and wind gusts to 50 mph will be the main threats.

Otherwise, showers and thunderstorms will likely be hard to
come by this afternoon as strong capping is in place. The
exception may be in central SD closer to increasing southwest
flow aloft and slightly stronger surface heating. If these
storms can develop, CAPE around 2000 J/kg as well as about 40
knots of deep layer shear as well as decent turning from
southeast to southwest in the lowest km. This will support all
modes of severe weather with an isolated tornado, hail to ping
pong ball and wind gusts to 70 mph. Unless the models are
completely incorrect in handling the capping inversion, the
chance for this very late afternoon and early evening convection
will be confined to areas west of the James River. One other
negative is the ongoing convection in central SD, which appears
to be taking a bite out of the daytime heating.

Farther east the threat will be more likely from about 8 pm to 2 am
as storms could become more rooted in a stronger LLJ with increasing
southwest flow aloft. This lay lead to a cluster of stronger
updrafts with half dollar sized hail, wind gusts to 60 mph and
pockets of heavy rain the main threats.

Instability lingers through late tonight into early Tuesday
morning as upper level support slowly moves through. Confidence
is low on additional stronger convection, but with potentially
1000-1500 J/kg of instability some isolated stronger storms will
be possible. For now the threat of heavy rain like the past
couple of days looks pretty low as storms should be more
progressive.

Instability is slow to shift southeast through the day on Tuesday
and should result in additional showers and potentially stronger
thunderstorms Tuesday afternoon. The better chance for this will
likely be south of a Yankton to Jackson MN line, with the better
chance from about 3 pm to 8 pm.

A stronger westerly jet aloft settles into the area Wednesday into
Thursday, with a fast moving trough expected to move through
Thursday night into Friday. This pattern should support dry
conditions on Wednesday and Thursday with a chance for showers and
thunderstorms late Thursday night, but more into Friday. Depending
upon the timing of the front with this wave on Friday, highs could
climb into the 90s in a few locations before a fairly strong shot of
cooler air moves in for next weekend where highs in the 70s are more
likely. Saturday night into Sunday will see a decent chance for
showers and thunderstorms as models are fairly agreeable with a wave
moving through, just not so much with the exact timing.

&&

.AVIATION /18Z TAFS THROUGH 18Z TUESDAY/...
Issued at 1130 AM CDT Mon Sep 7 2026

Scattered MVFR ceilings will remain possible through early to
mid afternoon. Showers and isolated thunderstorms will be
possible early this afternoon in central SD, towards KHON. Later
this afternoon through early evening, a small chance for severe
storms is expected near and west of the James River. If a storm
can develop a tornado, ping pong ball sized hail and wind gusts
to 65 mph are all possible. After about 2z, scattered showers
and thunderstorms, a few strong to severe, are expected near and
east of the James River. These showers and storms will likely
persist off and on through the night into Tuesday morning,
gradually shifting southeast. Within the stronger storms MVFR
conditions will be possible along with hail and gusty winds.

&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...None.
MN...None.
IA...None.
NE...None.

&&

$$

DISCUSSION...08
AVIATION...08