South Dakota Mesoscale Discussion

Areas affected…Central/eastern Wyoming through the Nebraska
Panhandle and southwestern South Dakota

Concerning…Severe potential…Watch possible

Valid 232008Z – 232215Z

Probability of Watch Issuance…60 percent

SUMMARY…Isolated strong to severe storms are expected to develop
through the remainder of the afternoon, though a more robust severe
threat ma develop along eastern portions of the discussion area
after around 21-22Z. A WW issuance is being considered.

DISCUSSION…The combination of 1) lift associated with an
approaching mid-level low over northwestern Wyoming and vicinity, 2)
weak upslope due to light northerly surface flow across much of the
discussion area, and moderate instability owing to 70s F surface
temps and steep mid-level lapse rates is contributing to a gradual
expansion in convective coverage across the discussion area. Though
low-level shear is generally weak, the combination of modestly
strong (40-kt) deep shear will contribute to some organization of
storms across central Wyoming over the next 1-2 hours along with an
associated threat for hail/wind. The extent of convective coverage
is still a bit uncertain in this area, however, as storms remain a
bit too sparse in coverage to necessitate a WW issuance in the short

The greater chance of a WW issuance will exist across the eastern
half of the discussion area through the afternoon and early evening.
By this time, upstream storms will have had a chance to develop
more mature cold pools and grow upscale while encountering better
instability via a pool of low to mid-60s F dewpoints across western
portions of NE/SD. Convective trends are being monitored in the
event that this scenario necessitates a WW issuance over time.

..Cook/Thompson.. 08/23/2019

…Please see for graphic product…


LAT…LON 43340825 44020769 44210566 44020401 43250298 42190257
41180271 41000367 41080546 41220705 41730786 42420841

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