ACUS11 KWNS 281941
SWOMCD
SPC MCD 281940
SDZ000-NDZ000-MTZ000-WYZ000-282145-

Mesoscale Discussion 2330
NWS Storm Prediction Center Norman OK
0240 PM CDT Mon Sep 28 2026

Areas affected...western South Dakota vicinity

Concerning...Severe potential...Watch unlikely

Valid 281940Z - 282145Z

Probability of Watch Issuance...5 percent

SUMMARY...Isolated strong to severe thunderstorms may produce
sporadic hail through evening. Severe potential is expected to
remain limited, and a watch is not anticipated.

DISCUSSION...Thunderstorms are developing near the Black Hills
across northeast WY this afternoon. This activity is developing near
the surface low and attendant cold front within an area that has
seen less cloudiness/stronger heating. An area of cumulus
development is noted in visible satellite imagery where clearing has
been more prevalent across northwest SD into southwest ND.
Additional thunderstorm development is expected within this area
over the next few hours.

Latest mesoanalysis shows MLCAPE around 1000-1500 J/kg and 7-7.5
C/km midlevel lapse rates across the region, which aligns well with
18z RAOBS from UNR and BIS. Effective shear magnitudes around 30 kt
and elongated hodographs above 2 km in combination with this
thermodynamic environment suggests that a few organized updrafts
could support marginally severe hail. With time, and northeast
extent, convection may become more elevated given greater low-level
inhibition where cloudiness has persisted, and as the cold front
begins to surge east/southeast during the evening.

..Leitman/Gleason.. 09/28/2026

...Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fjg!4PlE4YHOnIB_vCEHRPvbycAZugV3TWlv4GR22pcSaBHQemlBxdYDr66FtR1Idt59mCxiFgaUg90Wear4d7yOx3CuWw8$ for graphic product...

ATTN...WFO...ABR...BIS...UNR...BYZ...

LAT...LON 43940426 44030437 44440477 44580487 45020470 45900400
46360322 46590226 46580178 46450131 46210092 45720060
44920073 44340101 43950156 43630251 43550340 43940426

MOST PROBABLE PEAK WIND GUST...UP TO 60 MPH
MOST PROBABLE PEAK HAIL SIZE...UP TO 1.25 IN


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--- scorpsmtpd
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