Severe Storm Outlook Narrative (AC)
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ACUS11 KWNS 171852
SPC MCD 171851

Mesoscale Discussion 0068
NWS Storm Prediction Center Norman OK
1251 PM CST Sat Feb 17 2018

Areas affected...Parts of the eastern West Virginia
Panhandle/western Maryland and south central Pennsylvania

Concerning...Heavy snow

Valid 171851Z - 172245Z

SUMMARY...A period of heavy snow rates, around or in excess of 1
inch per hour, appears possible during the 2-6 PM EST time frame,
particularly near and east/southeast of the Altoona/State College

DISCUSSION...Large-scale forcing for ascent, downstream of a short
wave impulse turning eastward into the lower Ohio Valley, is
contributing to increasing saturation at mid-levels, across and
northeast/east of the central Appalachians.  Associated
precipitation will result in increasing saturation through the lower
levels to the surface within the next couple of hours, as stronger
mid-level forcing for ascent continues to spread northeastward out
of the lower Ohio Valley.

Models suggest that strengthening lift may become maximized within
the dendritic growth zone for a 2-4 hour period this afternoon,
including across areas to the lee of the Allegheny front, where
moistening southeasterly upslope flow may enhance snow rates and
maintain surface temperatures near freezing.  Southeastward across
the piedmont toward the Greater Baltimore and Washington D.C.
metropolitan areas, even with boundary layer evaporative cooling of
initial precipitation, surface temperatures may generally not fall
below the mid 30s.  This seems likely to result in lower potential
for sustained and/or accumulating snow.

..Kerr.. 02/17/2018

...Please see for graphic product...


LAT...LON   39557847 40377804 40787724 40527658 39977661 39697732
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