South Dakota Mesoscale Discussion

Areas affected…far northeast WY…far southeast MT…northwest
SD…far southwest ND

Concerning…Severe potential…Watch unlikely

Valid 172045Z – 172145Z

Probability of Watch Issuance…20 percent

SUMMARY…A few severe gusts (60-70mph), associated with high-based
thunderstorms, are possible this afternoon as storms move northeast
into western parts of the Dakotas. The expected coverage/intensity
of the severe risk will likely preclude a severe thunderstorm watch

DISCUSSION…A compact, negatively tilted mid-level shortwave
trough, is moving northeast across central WY this afternoon.
High-based, skeletal convection over central WY has gradually moved
east into the western part of a low-level moisture/instability plume
located over the Dakotas. Ample deep-layer shear will provide
support for some storm organization. Coupled with evaporative
cooling, the intensification of the background wind field is
becoming more favorable for momentum transfer of stronger flow to
the surface with the stronger downdrafts. A 53kt gust measured by
the Gillette, WY ASOS at 2008z is probably indicative of gust
potential with the strongest cores for at least the next several
hours. Yet, the smaller storm size will probably confine the severe
risk to isolated coverage before the risk gradually wanes later this
evening as storms move northeast into west-central and northwest ND.

..Smith/Grams.. 09/17/2019

…Please see for graphic product…


LAT…LON 44970510 46680411 46870329 46580255 46120223 43690356
43940450 44970510

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