ACUS11 KWNS 271914
SWOMCD
SPC MCD 271913
SDZ000-NEZ000-272115-

Mesoscale Discussion 1767
NWS Storm Prediction Center Norman OK
0213 PM CDT Mon Jul 27 2026

Areas affected...Southwest South Dakota and adjacent portions of
northwest Nebraska

Concerning...Severe potential...Watch possible

Valid 271913Z - 272115Z

Probability of Watch Issuance...60 percent

SUMMARY...Thunderstorms developing across southwest South Dakota
will likely pose a severe wind threat as they spread east across
South Dakota and northwest Nebraska. Watch issuance may be required
to address this potential.

DISCUSSION...Recent visible/reflectivity imagery and lightning data
shows early stages of deep convection within the Black Hills in
southwest SD. This activity is largely being driven by weak upslope
ascent, but should gradually propagate eastward as convection
deepens and becomes increasingly influenced by mean westerly flow
aloft. However, the KUDX VWP has recently sampled somewhat modest
winds between 5-7 km (around 25 knots), resulting in slightly weaker
deep-layer bulk shear than depicted by recent mesoanalyses.
Regardless, the thermodynamic environment features sufficient
buoyancy for sustained deep convection - especially with eastward
extent into a plume of low 60s dewpoints. Additionally, strong
heating has steepened low-level lapse rates to around 9 C/km
downstream, which should foster cold pool development and further
promote eastward propagation.

Consequently, the expectation is for initially discrete convection
to gradually grow upscale and propagate eastward through the evening
hours. Severe winds will be the primary concern and could be as
strong as 55-70 mph based on environmental conditions and output
from recent high-res guidance, though the modest kinematic
environment casts some uncertainty on overall storm
organization/intensity. Trends will continue to be monitored and
watch issuance may be required if/when upscale growth occurs.

..Moore/Hart.. 07/27/2026

...Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fjg!-i3d8VpmJBnSz7XvzbaKoD10AJCJZx-XQHLx24FHsd_S9M2sBzQNZatqmird7rw55hp-prM7V9Q0w6IT6VChZNTHEpc$ for graphic product...

ATTN...WFO...ABR...LBF...UNR...CYS...

LAT...LON 42780079 42800315 42880361 43070386 43420405 44670399
44960340 44980263 44920148 44540085 44070053 43620019
43200023 43000036 42780079

MOST PROBABLE PEAK WIND GUST...55-70 MPH
MOST PROBABLE PEAK HAIL SIZE...UP TO 1.25 IN


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