ACUS11 KWNS 271843
SWOMCD
SPC MCD 271843
NEZ000-SDZ000-272045-

Mesoscale Discussion 2149
NWS Storm Prediction Center Norman OK
0143 PM CDT Thu Aug 27 2026

Areas affected...portions of the Black Hills into northwestern and
west-central Nebraska

Concerning...Severe potential...Watch likely

Valid 271843Z - 272045Z

Probability of Watch Issuance...80 percent

SUMMARY...Thunderstorms forming on the Black Hills will evolve
southeastward through the evening, bringing a risk for large to very
large hail and severe wind gusts.

DISCUSSION...Latest surface analysis depicts a corridor of low-60s F
dewpoints across northwestern Nebraska and southwestern South Dakota
that have been maintained by moist southerly/southeasterly low-level
flow. Combined with strong diurnal heating and weak ascent
associated with a subtle mid-level wave progressing southeastward
out of eastern Montana, convective initiation is likely across the
Black Hills within the next 1-2 hours. Supercells will be the
initial storm mode owing to strong northwesterly flow aloft and
40-45 kts of effective shear. While some uncertainty remains
regarding convective evolution (particularly supercell longevity and
the potential for eventual upscale growth), very steep mid-level
lapse rates and elongated hodographs sampled by the 18z UNR observed
sounding will support a risk for large to very large hail (up to
2-3+ inches in diameter) with any sustained supercells. Severe to
perhaps significant severe wind gusts of 65-75 mph may also occur
with these supercells, with a greater threat for severe gusts likely
to accompany any convective cluster that eventually evolves as this
activity progresses southeastward. Regardless of the exact storm
mode evolution, a Severe Thunderstorm Watch will likely be needed
once convective development currently noted over the Black Hills
matures.

..Chalmers/Mosier.. 08/27/2026

...Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fjg!8T5GjKQRTggEVuJGJlb1dmOZW48c7iK3YQiMnRlg1bsBO0AoUnS83rAQcgTZxy0FLxiSGjvS2yjlTn5k2dmUyNZB87c$ for graphic product...

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

LAT...LON 44280348 43540157 43030059 42710030 42330028 41850058
41500113 41320192 41520251 42000294 43020345 44050394
44310382 44280348

MOST PROBABLE PEAK WIND GUST...65-80 MPH
MOST PROBABLE PEAK HAIL SIZE...2.00-3.50 IN


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--- scorpsmtpd
* Origin: capitolcityonline.net * KY, USA (1:2320/107)