SPC MD 1906

MD 1906 CONCERNING HEAVY SNOW FOR WESTERN AND CENTRAL DAKOTAS

Mesoscale Discussion 1906
NWS Storm Prediction Center Norman OK
1256 PM CST Sun Dec 25 2016

Areas affected...Western and Central Dakotas

Concerning...Heavy snow 

Valid 251856Z - 260000Z

SUMMARY...A band of heavy snow with rates around 1 inch per hour
will continue developing northward across parts of the northern
Plains this afternoon.  Occasional sleet and freezing rain will also
be located over eastern parts of the threat area.  Local blizzard
conditions are expected to develop this afternoon over western South
Dakota into western and central North Dakota as surface winds
increase to 30-40 mph with locally higher gusts.

DISCUSSION...An intense upper-level low over the Wyoming/Colorado
border is lifting northeastward toward the northern Plains, in
association with a deep surface low that is consolidating over
northeast Colorado.  The surface low is expected to deepen as it
moves northeast across north central Nebraska this afternoon. 
Strong divergence aloft within the left exit region of an
upper-level jet streak progressing into the central plains coupled
with strengthening low-level convergence to the northwest and north
of the deepening surface low are generating an axis of focused
deep-layer ascent from western parts of Nebraska and South Dakota. 
The zone of ascent will spread into North Dakota this afternoon.  

Snow is expected to increase into southwest South Dakota this
afternoon, with additional areas of occasionally heavy snow
spreading from west-central and northwest South Dakota into
western/central North Dakota.  Strong warm advection from central
South Dakota into central North Dakota, accompanied by an
above-freezing layer in forecast soundings between 850-700 mb, will
also promote periods of sleet/freezing rain this afternoon before
transitioning to primarily snow by evening.

Surface winds are also expected to increase to 30-40 mph with
locally higher gusts during the afternoon over parts of western
South Dakota into western/central North Dakota, with blowing snow
lowering visibilities and local blizzard conditions possible.

..Weiss.. 12/25/2016

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

ATTN...WFO...FGF...ABR...BIS...UNR...

LAT...LON   43770044 43070149 43050286 43500390 44760395 46860361
            48560346 48990079 48569915 47349881 45549992 43770044 

Read more

from SPC Forecast Products http://ift.tt/1aX8HzW