ZCZC SPCSWOMCD ALL
ACUS11 KWNS 161607 
SPC MCD 161607 
SDZ000-NEZ000-MTZ000-WYZ000-162200-

Mesoscale Discussion 1884
NWS Storm Prediction Center Norman OK
1007 AM CST Fri Dec 16 2016

Areas affected...Much of western and central SD...far northeast WY
and extreme northwest NE

Concerning...Heavy snow 

Valid 161607Z - 162200Z

SUMMARY...Snowfall rates near 1 inch per hour will expand eastward
across parts of northeast WY, far northwest NE and much of SD
through the afternoon hours. Some localized but brief periods of 2
inch per hour rates will be possible.

DISCUSSION...Snowfall coverage is expanding across the northern
Plains late this morning. Mainly light snow is being observed across
parts of MT, WY, SD and NE, but some recent moderate to heavy
observations were noted across far northeast WY into southwest SD
and near the tri-state border region of WY/SD/NEB. Snowfall coverage
should continue to expand eastward across the region and intensity
likely will also increase, with rates near 1 inch per hour becoming
more widespread. 

This is in response to increasing forcing for ascent ahead of an
upper trough currently digging south-southeast across the
northwestern U.S. Several shortwave impulses will migrate
east-northeast across the central and northern Rockies into the
northern Plains, providing focus for a large area of heavy snow.
Recent RAP point forecast soundings show ascent through a deep
saturated thermodynamic profile with a dendritic growth zone depth
ranging from 10kft to 15kft . This will support efficient snow
production and some localized and brief periods of rates nearing 2
inches per hour.  This system will progress eastward through the day
and snowfall rates should decrease across western portions of the
MCD area during the evening.

..Leitman.. 12/16/2016

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

ATTN...WFO...FSD...ABR...LBF...UNR...CYS...BYZ...

LAT...LON   45100385 45190272 45260089 45209914 45039870 44569817
            44199811 43779828 43339922 43030024 42810179 42740302
            42910400 43760489 44100497 44460510 44830475 45100385 

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