South Dakota Mesoscale Discussion

Areas affected…North-Central and Northeast South Dakota

Concerning…Heavy snow

Valid 090146Z – 090545Z

SUMMARY…Heavy snow with rates of 1 inches per hour likely this
evening.

DISCUSSION…A compact mid-level short-wave trough is progressing
eastward through central South Dakota, with pronounced low-level
theta-e advection. Consequently, steepening mid-level lapse rates
and low-level (850-700 mb) frontogenesis is occurring across
portions of north-central and northeast South Dakota. Regional radar
shows an elongated snowband developing in association with this
mesoscale forcing for ascent, from central to southeast South
Dakota, with light to moderate occurring and some higher
reflectivity returns evident on the most recent scans.

The latest high-resolution guidance indicates continued expansion
and intensification of this snowband, which should pivot northward
with time and become quasi-stationary later this evening across
north-central and northeast South Dakota. Heavy snow, with rates of
1 inches per hour, is likely to develop through mid to late
evening. Forecast soundings indicate the potential for continued
strong low-level theta-e advection that may result in mid-level
destabilization through the dendtric layer, and thus potential for
thundersnow. Should this occur, locally higher snowfall rates of 2
inches per hour are possible.

..Karstens.. 02/09/2020

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

ATTN…WFO…FSD…ABR…

LAT…LON 45469975 45040047 44550020 44209909 44069708 44379649
44999665 45319757 45519888 45469975

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