Severe Thunderstorm Warning 287, NWS Sioux Falls, SD

Area Forecast Discussion
National Weather Service Sioux Falls SD
1053 PM CDT Mon Sep 7 2026

.KEY MESSAGES...

- A line of storms continues to move east just north of the
  Missouri Valley late this evening. Wind gusts to 65 mph and
  quarter sized hail are possible. Tornado risk is low but not
  zero. Locally heavy rain and isolated flash flooding are also
  a concern.

- Additional scattered and possibly severe storms are possible
  into the overnight hours and again Tuesday afternoon/evening.
  The main threats remain quarter sized hail, wind gusts to 65
  mph, and locally heavy rain.

- 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.

&&

.UPDATE...
Issued at 1040 PM CDT Mon Sep 7 2026

A few storms, some strong to severe, have been moving along the MO
River this evening. Although generally trending downward, still may
see some wind gusts to 65 mph and quarter sized hail as storms are
beginning to show more linear characteristics over the last 30
minutes with shear perpendicular to the storms. Tornado risk is low.
Main threats may be shifting to wind and locally heavy rain/isolated
flooding issues as the storms train over the same areas near the 700
mb convergence, the 850 mb boundary, and the LLJ. Storm motion
generally will be east to northeast.

Next area to watch is with the next wave out of NE through the
overnight hours. Guidance shows additional convective development
with some weak to moderate instability. LLJ also may aid in keeping
storms around through the overnight hours. Confidence is low in the
severe potential given the decreasing shear and instability through
the overnight hours into early Tuesday.

&&

.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 /00Z TAFS THROUGH 00Z WEDNESDAY/...
Issued at 633 PM CDT Mon Sep 7 2026

Latest radar and satellite imagery shows remaining showers in and
around KBKX pushing off to the northeast early this evening. At the
same time, thunderstorms are developing southwest of KAGZ. These
thunderstorms will continue to push off to the northeast through the
rest of the evening hours. Will watch convective trends but the
coverage of thunderstorms could also increase as well. Have kept
PROB30/TEMPO groups in KFSD and KSUX's TAFs through most of the
overnight hours. Lowered ceilings and visibilities are expected
within the storms, potentially down to MVFR levels. Some of these
storms could be strong to severe with large hail and damaging winds
as the main hazards. Chances for storms looks to wane into tomorrow
morning though showers may persist through the morning and into the
afternoon timeframe. A cold front will be pushing through the
forecast area tomorrow, turning winds to out of the northwest in its
wake. This same front looks to develop another round of
thunderstorms across northwest Iowa towards the end of the period
tomorrow afternoon.

&&

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

&&

UPDATE...SG
DISCUSSION...08
AVIATION...Meyers

Hazardous Weather Outlook
National Weather Service Sioux Falls SD
234 PM CDT Mon Sep 7 2026

IAZ001>003-012>014-020>022-031-032-MNZ071-072-080-081-089-090-097-
098-NEZ013-014-SDZ038>040-050-052>071-081945-
Lyon-Osceola-Dickinson-Sioux-O'Brien-Clay-Plymouth-Cherokee-
Buena Vista-Woodbury-Ida-Lincoln-Murray-Cottonwood-Nobles-Jackson-
Pipestone-Rock-Dixon-Dakota-Beadle-Kingsbury-Brookings-Gregory-
Jerauld-Sanborn-Miner-Lake-Moody-Brule-Aurora-Davison-Hanson-McCook-
Minnehaha-Charles Mix-Douglas-Hutchinson-Turner-Bon Homme-Yankton-
Union-
234 PM CDT Mon Sep 7 2026

This Hazardous Weather Outlook is for northwest Iowa, west central
Iowa, southwest Minnesota, northeast Nebraska, central South
Dakota, east central South Dakota, south central South Dakota and
southeast South Dakota.

.DAY ONE...This afternoon and tonight.

Isolated strong to severe thunderstorms are possible near and west
of the James River late this afternoon and early this evening.
Confidence is low in development, but if something can develop an
isolated tornado, hail to ping pong ball and wind gusts to 70 mph are
possible.

Additional strong to severe storms will be possible from roughly 8 pm
to 2 am near and east of the James River. The main threat from these
storms will be half dollar hail and 60 mph winds.

.DAYS TWO THROUGH SEVEN...Tuesday through Sunday.

A couple strong storms may be possible for northwestern Iowa into
eastern Nebraska and southern Minnesota Tuesday afternoon and
evening.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may be needed.

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