South Dakota Mesoscale Discussion

Areas affected…Far eastern Wyoming into extreme southwestern South
Dakota and extreme western Nebraska

Concerning…Severe potential…Watch unlikely

Valid 302254Z – 310030Z

Probability of Watch Issuance…5 percent

SUMMARY…Isolated damaging wind gusts and perhaps large hail are
possible with the stronger storms developing off of the higher
terrain. Given the isolated and brief nature of the severe threat, a
WW issuance is not currently anticipated.

DISCUSSION…Convection has recently begun to intensify along the
higher terrain in far eastern WY with the aid of afternoon peak
heating and the approach of a vort max in central WY. Buoyancy
across the discussion area is rather modest, with steep mid-level
lapse rates of around 8 C/km fostering MLCAPE values mainly between
500-1000 J/kg. Combined with effective bulk shear values between
40-50 knots, organization into multicellular clusters and perhaps
brief, transient supercell structures are possible. Organization and
acquired mid-level rotation of the more robust storms may pose a
threat for a few severe hail stones. Though low-level lapse rates
are not particularly steep, a dry sub-cloud layer extending up to
600 mb suggests that adequate evaporative cooling may also transpire
to support a few damaging wind gusts with the most intense storms.
Nonetheless, the isolated nature of the severe threat precludes a WW

..Squitieri/Dial.. 08/30/2019

…Please see for graphic product…


LAT…LON 41540490 42810572 43330580 43680560 43850501 43850414
43030344 41810287 41460293 41190400 41540490

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