Mesoscale Discussion 0023
NWS Storm Prediction Center Norman OK
0756 PM CST Fri Jan 06 2017
Areas affected...portions of northeast TN...western NC...western
into central VA and southeast WV
Concerning...Heavy snow
Valid 070156Z - 070800Z
SUMMARY...Snow will increase in intensity and coverage across the
MCD area during the nighttime hours. One inch per hour snowfall
rates will be common, with spotty/brief periods of 2 inch per hour
rates not out of the question. The heaviest snowfall is expected to
begin in the next 2-3 hours and spread southwest to northeast across
the MCD area overnight.
DISCUSSION...Most of the MCD area is below freezing as of 0130z, or
soon will be. Latest RAP forecast soundings indicate a deep,
saturated sub-freezing vertical profile. Forcing for ascent is
expected to increase this evening as a lead shortwave impulse ahead
of the main upper trough ejects across the central Appalachians.
This will result in increased frontogenetic forcing in the 700-500
mb layer, where a somewhat shallow but sufficient dendritic growth
zone resides. Low level cold advection will maintain a cold profile,
while strong mid-level south/southwesterly flow continues to inject
moisture across the region. Furthermore, north/northeast winds below
850 mb will further support heavy snow development through
orographic upslope processes. Heavy snowfall rates increasing to
around 1 in/hr are expected to be underway across the region by
03z-06z and continue through the nighttime hours. Some brief and
spotty areas with rates near 2 in/hr, especially along the spine of
the Appalachians, cannot be ruled out.
..Leitman.. 01/07/2017
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...AKQ...LWX...RAH...RNK...RLX...GSP...MRX...JKL...
LAT...LON 35828385 37148261 37908107 38178004 38047921 37787852
37187859 36217966 35438131 35208269 35168335 35398385
35828385
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