|Mesoscale Discussion 234|
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Mesoscale Discussion 0234
NWS Storm Prediction Center Norman OK
0452 AM CDT Fri Apr 13 2018
Areas affected...the southwest quarter of South Dakota and vicinity
Valid 130952Z - 131545Z
SUMMARY...Snowfall rates locally in excess of 1"/hr near the Black
Hills should expand eastward with time across a larger portion of
the southwest South Dakota Vicinity.
DISCUSSION...Latest surface obs show gradually cooling temperatures
across the discussion area, with what appears to be melting-enhanced
cooling in the Black Hills area (the temperature fell to a now
steady 32 degrees at Rapid City over the past couple of hours).
Persistent moderate to heavy snowfall is indicated by radar within a
deformation zone across the Black Hills area, with rainfall farther
south and east where temperatures remain in the mid to upper 30s.
However, as the slow-moving upper system drifts eastward, continued
gradual cooling/persistent precipitation across a larger portion of
southwest South Dakota should result in an eastward expansion of
substantial snowfall -- in line with latest model output. Strength
of ascent across the region -- and possibly some convective
enhancement -- suggests snowfall rates exceeding 1" per hour can be
expected over the next several hours.
...Please see www.spc.noaa.gov for graphic product...
LAT...LON 43960323 44600323 44970280 45170202 44229987 43180019
42870161 42970263 43380317 43960323
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