|Mesoscale Discussion 25|
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Mesoscale Discussion 0025
NWS Storm Prediction Center Norman OK
0604 PM CST Fri Jan 12 2018
Areas affected...Portions of southeastern OH...WV...western
MD...PA...NY...VT...and northern NH
Concerning...Winter mixed precipitation
Valid 130004Z - 130600Z
SUMMARY...An initial transition from rain to freezing rain, then to
sleet and snow will occur this evening as a cold front moves
DISCUSSION...23Z surface analysis shows a cold front extending from
northern VT into central NY/PA, and then continuing into western MD
and WV. The cold front will develop generally east-southeastward
through 06Z, with the 32F surface isotherm lagging the initial wind
shift by about 90-100 miles. A mid/upper-level trough/low centered
over KY/TN will continue moving east-northeastward this evening.
Large-scale lift associated with the upper trough/low has promoted a
broad area of mostly light to moderate precipitation from WV
northward to NY.
Recent surface observations and local storm reports indicate a
relatively narrow corridor of freezing rain is occurring
along/behind the surface freezing-line intersection with the ongoing
light/moderate rain. Freezing rain rates of at least several
hundredths of an inch per hour will be likely, with rates up to 0.10
inch per hour possible in the heaviest showers. These higher rates
appear more likely across northern PA into south-central NY over the
next few hours as an area of moderate to locally heavy rain moves
across this region and surface temperatures fall below freezing.
A transition to sleet and then snow will occur as a residual
low-level warm nose centered around 900-750 mb quickly erodes with
the approach of the mid/upper level trough/low. Some of the snow may
become heavy at times, with rates around 1 inch per hour, especially
across western PA/NY into southeastern where this transition to snow
is already occurring.
...Please see www.spc.noaa.gov for graphic product...
LAT...LON 39617869 38727987 38498060 38488193 38748282 39038294
40118224 41338052 42617845 44127641 44517569 44987481
45097252 45047168 45387135 45337108 44647106 43647240
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