MD 0015 CONCERNING HEAVY SNOW FOR THE BLUE RIDGE OF WESTERN NORTH CAROLINA AND ADJACENT PORTIONS OF THE SOUTHERN APPALACHIANS

Mesoscale Discussion 0015
NWS Storm Prediction Center Norman OK
0954 PM CST Thu Jan 07 2021

Areas affected...The Blue Ridge of western North Carolina and
adjacent portions of the southern Appalachians

Concerning...Heavy snow 

Valid 080354Z - 080700Z

SUMMARY...Heavy snow is expected to develop along the North Carolina
Blue Ridge into Great Smoky Mountains, at rates up to 1-2 inches per
hour by 1-3 AM EST.

DISCUSSION...The exit region of an 80-90 kt, cyclonic 500 mb jet
streak is in the process of overspreading the southern Appalachians
vicinity, with associated forcing for ascent and cooling
contributing to steepening mid-level lapse rates.  This includes the
eastern slopes of the North Carolina Blue Ridge into the Great Smoky
Mountains, where low-level warm advection to the east of an
approaching mid-level low will contribute to lift during the next
few hours.

Models suggest that orographic forcing will become maximized across
the higher terrain by 06-08Z, when strong upward vertical motion may
focus within the favorably cold mid-level temperatures conducive to
large dendritic ice crystal growth.  Although lower levels near and
just above the surface may be initially relatively warm and dry,
quick saturation and cooling of this air mass is expected due to
evaporation and melting of heavy precipitation.  Aided by
precipitable water increasing in excess of .5 inches, at least a
couple hour period of heavy snow rates on the order of 1-2 inches
per hour appears possible.

..Kerr.. 01/08/2021

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

ATTN...WFO...RNK...GSP...MRX...

LAT...LON   35778302 36098232 36408158 36108070 35628135 35258205
            35148309 35548337 35778302 

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