ACUS11 KWNS 080940
SWOMCD
SPC MCD 080939
NEZ000-SDZ000-081215-

Mesoscale Discussion 1861
NWS Storm Prediction Center Norman OK
0439 AM CDT Sat Aug 08 2026

Areas affected...parts of west central Nebraska int
southwestern/south central South Dakota

Concerning...Severe potential...Watch unlikely

Valid 080939Z - 081215Z

Probability of Watch Issuance...20 percent

SUMMARY...A period of rapidly intensifying thunderstorm development
posing a risk for large hail appears possible by 5-7 AM CDT. Due to
the relatively isolated, and perhaps short-lived, nature of the
threat, it is not clear that this will require a severe weather
watch, but trends are being monitored.

DISCUSSION...Downstream of a subtle perturbation migrating around
the northern periphery of prominent mid-level ridging centered over
the southern Great Basin, large-scale ascent appears to be in the
process of increasing across the South Dakotas Badlands vicinity
through Nebraska Sandhills. This is being aided by
lower/mid-tropospheric warm advection, as veering and strengthening
flow in lower-levels (including to 30-40 kt around 850 mb) begins to
support a rapid return of low-level moisture above a relatively
cool/stable surface-based layer.

Forecast soundings, including latest Rapid Refresh guidance,
indicate that moistening near the initially dry base of the elevated mixed-layer air is contributing to strong destabilization, including
CAPE increasing in excess of 2000 J/kg. With pronounced veering of
winds with height contributing to strong deep-layer shear, the
environment is becoming increasingly conducive to the development of
supercells capable of producing large hail. Based on
convection-allowing and related output, and trends in latest
infrared satellite imagery, it appears that at least a few storms
may rapidly initiate during the 10-12Z time frame.

It is not clear how long this threat will continue after daybreak,
due to some combination of upscale convective growth, continued
warming (and increasing inhibition) aloft, and weakening of the
nocturnal low-level jet.

..Kerr/Smith.. 08/08/2026

...Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fjg!76Wz_pPtcRVh2NCWkZf1y7aUhijbGIqOug6AKYRYXrN5_IKiLHQ8hIP8xpGpjet-YUiWhue6H0HA_EoK086jEec7uRc$ for graphic product...

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

LAT...LON 43940163 43129981 41670016 41620135 43300220 43940163

MOST PROBABLE PEAK HAIL SIZE...1.50-2.50 IN


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