SPC MD 458



MD 0458 CONCERNING HEAVY SNOW FOR EASTERN SOUTH DAKOTA…SOUTHERN MINNESOTA…AND NORTHERN IOWA

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Mesoscale Discussion 0458
NWS Storm Prediction Center Norman OK
0514 AM CDT Sat Apr 27 2019

Areas affected...eastern South Dakota...southern Minnesota...and
northern Iowa

Concerning...Heavy snow 

Valid 271014Z - 271615Z

SUMMARY...Rain is beginning to transition to snow across portions of
eastern South Dakota. This trend will continue/expand through the
rest of the overnight.

DISCUSSION...Light-to-moderate rain persists across eastern South
Dakota, southern Minnesota, and northern Iowa this morning
associated with warm-air advection and 850-700 millibar
frontogenesis. A combination of wet-bulb cooling and precipitation
drag bringing down cooler air aloft have allowed surface
temperatures to fall from the low 40s a few hours ago into the
low-to-mid 30s within portions of the larger precipitation band.
This trend of transitioning from rain to snow should continue
through the rest of the morning. 

Snowfall rates occasionally approaching 1-2 inch per hour -- owing
to both embedded convective elements (supported by recent lightning
strikes across southeast South Dakota) and larger-scale forcing
associated with the warm-air advection and low-to-midlevel
frontogenesis -- will allow for accumulation despite surface
temperatures generally at or above 32F.

..Marsh.. 04/27/2019

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

ATTN...WFO...ARX...MPX...DMX...FSD...ABR...

LAT...LON   45219934 45139740 43899303 42729186 43229573 43839892
            45219934 

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