South Dakota Mesoscale Discussion

Areas affected…eastern Wyoming…western South Dakota…and far
northwestern Nebraska

Concerning…Severe potential…Watch possible

Valid 300138Z – 300415Z

Probability of Watch Issuance…60 percent

SUMMARY…Thunderstorm development is expected to increase across
the eastern Wyoming/western South Dakota vicinity, with large hail
likely to be the primary risk. WW issuance may be needed.

DISCUSSION…Latest radar shows convection developing across eastern
Wyoming and western South Dakota, in the vicinity of a southeast
Wyoming surface low. A warm front extends east from the low,
roughly along the Nebraska/South Dakota border, and model forecasts
continue to suggest that storms will increase in coverage to the
north of this boundary, as QG ascent gradually increases. While
timing of the onset of severe risk remains uncertain, ascent —
evident within WV imagery — continues spreading across central
Wyoming toward the discussion area, which suggests gradually
increasing potential for vigorous storms. With moderate CAPE above
700 mb and strong southwesterly flow aloft, supportive of rotating
updrafts, potential for large hail is evident. This may require WW
issuance in the next hour or so.

..Goss/Guyer.. 09/30/2019

…Please see www.spc.noaa.gov for graphic product…

ATTN…WFO…ABR…LBF…UNR…CYS…

LAT…LON 42900534 43700517 44930406 45660286 45730164 45290048
44490076 43620149 42770253 42480425 42900534

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