ZCZC SPCSWOMCD ALL
ACUS11 KWNS 240102 
SPC MCD 240102 
IAZ000-MNZ000-SDZ000-240700-

Mesoscale Discussion 0169
NWS Storm Prediction Center Norman OK
0802 PM CDT Fri Mar 23 2018

Areas affected...Portions of eastern SD...southwestern MN...and
northern IA

Concerning...Heavy snow 

Valid 240102Z - 240700Z

SUMMARY...A band of heavy snow will develop through the evening,
with snowfall rates around 1 inch per hour likely.

DISCUSSION...A band of rain/thunderstorms across southeastern SD
into northwestern IA as of 01Z is being supported by lift associated
with a shortwave trough ejecting northeastward over the
northern/central Plains. A strengthening southeasterly low-level jet
will increase in the thermal gradient around 850 mb. Although some
sleet may occur initially, forecast soundings from the NAM/HRRR
suggest mid-level cooling with the approach of the shortwave trough
will encourage a fast transition from rain to snow across eastern SD
into southern MN and northern IA as ongoing precipitation shifts
into this area through 03-05Z.

A band of heavy snow will develop across this region later this
evening into the early overnight hours, with strong low-level
frontogenetic forcing and deep ascent occurring through the
dendritic growth zone likely supporting snowfall rates around 1 inch
per hour. Some localized higher rates to around 2 inches per hour
may be possible within convective elements of the band, and an
isolated lightning strike or two cannot be ruled out. Of note, there
will likely be a sharp northern gradient to the heavy snow due to a
residual dry low-level airmass being reinforced by strong
east-northeasterly surface winds across parts of central/eastern MN.

..Gleason.. 03/24/2018

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

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

LAT...LON   44179713 44569745 45219736 45639677 45579617 45379555
            45039488 44619427 44229364 43929318 43529272 43089247
            42759242 42569291 42969378 43329480 43449561 43709648
            44179713 

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