Severe Thunderstorm Warning 243, NWS Aberdeen, SD

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
657 PM CDT Sat Aug 29 2026

.KEY MESSAGES...

- Marginal Risk (level 1 of 5) for severe storms tonight, then
  again Sunday afternoon/night. Main threats include wind gusts
  up around 60 mph along with quarter size hail.

- Temperatures will remain 5-7 degrees above normal (80s to lower
  90s) through much of next week.

&&

.UPDATE...
Issued at 642 PM CDT Sat Aug 29 2026

See below for an aviation forecast discussion for the 00Z TAFs.

Also, looks like there was enough low level forcing to get a few
storms to go in this 2000-3000J/kg CAPE environment, with 40+
knots of deep layer shear and long, straight-line hodographs.
Near storm environment says there could eventually be a tornado
threat under one of these supercells. But, so far, haven't seen
much for low level rotation on anything that's developed. Will
keep watching. For now, the large hail (1-2inch hail) and 60mph
wind threat continues.

Finally, these storms are producing excessive heavy rainfall.
The slow moving nature of these storms and their tendency, thus
far this evening, to train over each other is cause for flood-
related headlines this evening.

&&

.DISCUSSION...
Issued at 227 PM CDT Sat Aug 29 2026

Mid-level clouds with bases around 15k feet (give or take) continue
across the eastern CWA but look to be exiting over the next few
hours, also taking with it any sprinkles associated with them. Still
expect to see a lull in precip potential for the rest of the
afternoon into early evening. Focus for shower/thunderstorm
development later today will shift into eastern WY/CO into the NE
panhandle northward into western SD. SPC REFS and HREF ensemble
paintball output shows any potential activity moving into central SD
generally between 02Z-05Z, then spreading eastward across the CWA
during the overnight hours. Areal coverage looks to diminish east of
the James River from 09Z to 12Z. Current PoPs generally show this
idea where good agreement in the paintball output over central/north
central SD gives 60-90% chances for precip, diminishing to 30
percent or less east of the James River after 09Z. MUCAPE overnight
generally around 1000-1500 J/KG across central SD into the James
valley, with 30-40 kts effective shear. Marginal Risk continues for
the overnight hours, with main threats being winds up to around 60
mph and hail around quarter size.

On Sunday, a surface low will develop near the MT/ND border
southward across western SD. A warm front will also extend eastward
from this low across SD into southern MN. Surface dewpoints still
progged to reach the upper 60s to around 70 degrees across the
region, while cooling aloft occurs later in the day with the
approach of a shortwave trough. Expecting scattered storms to
develop by late afternoon near the surface low, with activity moving
eastward into the evening and overnight hours. Marginal Risk (level
1 out of 5) for severe storms exists again on Sunday.

Surface high pressure builds in across the area on Monday, with
lower dewpoints dropping into the 50s for most areas. Much more
stable air mass in place on Monday, so a dry forecast is in place
for the time being.

Precipitation chances (40-60%) return to the region Tuesday/Tuesday
night as shortwave energy moves northeast into the area. Low-level
moisture begins to increase once again with dewpoints forecast to
reach the mid/upper 60s once again.

&&

.AVIATION /00Z TAFS THROUGH 00Z MONDAY/...
Issued at 642 PM CDT Sat Aug 29 2026

Terminals KABR,KATY,KPIR,KMBG

VFR conditions are forecast to prevail through the next 24 hours.
Scattered TSRA/SHRA are expected to move east across the region
this evening into the overnight hours. Will use TEMPO/PROB30 to
handle this, with indications suggesting northern SD may see
higher areal coverage of precipitation vs other areas. Any
TSRA/SHRA that moves over a TAF site is capable of brief
MVFR/IFR VSBY.

&&

.ABR WATCHES/WARNINGS/ADVISORIES...
SD...None.
MN...None.

&&

UPDATE...10
DISCUSSION...TMT
AVIATION...10

Hazardous Weather Outlook
National Weather Service Aberdeen SD
315 AM CDT Sat Aug 29 2026

MNZ039-046-SDZ003>011-015>023-033>037-045-048-051-301200-
Traverse-Big Stone-Corson-Campbell-McPherson-Brown-Marshall-Roberts-
Walworth-Edmunds-Day-Dewey-Potter-Faulk-Spink-Clark-Codington-Grant-
Hamlin-Deuel-Stanley-Sully-Hughes-Hyde-Hand-Jones-Lyman-Buffalo-
315 AM CDT Sat Aug 29 2026 /215 AM MDT Sat Aug 29 2026/

This Hazardous Weather Outlook is for west central Minnesota,
central South Dakota, north central South Dakota and northeast
South Dakota.

.DAY ONE...Today and tonight.

A Marginal Risk for severe weather, a level 1 of 5 threat, is in
place for storms late this afternoon and into the overnight hours.
The best chance for showers and thunderstorms (30-60% chance) is over
north central South Dakota. The main severe threats will be hail of
one inch in diameter and wind gusts to 60 miles per hour. Heavy
rainfall is also possible.

.DAYS TWO THROUGH SEVEN...Sunday through Friday.

On Sunday, another Marginal Risk is in place for the entire area
during the late afternoon through overnight hours, with the best
chances for showers and thunderstorms (30-60% chance) over northern
South Dakota. The main severe threats will once again be hail of one
inch in diameter and wind gusts to 60 miles per hour.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may be requested. Weather spotters are encouraged
to submit reports to the National Weather Service in Aberdeen. The
public can submit reports on our web page, Facebook page, or our X
feed.

SRF

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Preliminary Local Storm Report
National Weather Service Aberdeen SD
555 PM CDT Sat Aug 29 2026

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0550 PM     Hail             9 SW Bowdle             45.37N 99.80W
08/29/2026  E1.50 Inch       Walworth           SD   Public

            Hail was a varity of sized, from pea all the
            way up to ping pong ball sized.

&&

NV

Preliminary Local Storm Report
National Weather Service Aberdeen SD
648 PM CDT Sat Aug 29 2026

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0630 PM     Hail             5 SSE Lowry             45.24N 99.96W
08/29/2026  E0.70 Inch       Potter             SD   Public

            Pea to Dime sized hail fell. Time estimated
            by radar.

&&

NV