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Area forecast discussion 
National Weather Service Pittsburgh PA
247 PM EST Friday Jan 30 2015

Synopsis...
high pressure will build in through Saturday. Low pressure will
bring wintry weather Sunday into Monday.

&&

Near term /through tonight/...
scattered-numerous snow showers will continue across the area into early evening...though
should rapidly dmnsh after sunset as high pressure builds further into
the region and subsidence increases. Cold temperatures are expd tonight also...with wind
chills approaching -10 to -15 for areas NE-southeast of pit where wind chill
advisories were maintained.

&&

Short term /Saturday through Monday/...
high pressure should continue dry weather into Sat evening. A digging upper trough is
prognosticated to advance out of the plains and track across the Great Lakes and
Ohio Valley region sun into Monday. Associated surface low pressure is prognosticated to
deepen as it moves across the Tennessee and Ohio Valley regions also. This will
spread snow into the region lt Sat night through Monday morning with deep
available moisture and Omega.

With a closed 850mb low...a more prolonged precipitation event is expd as
opposed to the open system earlier in the weak. With enough
potential for heavy snow or a snow/ice mix...issued a Winter Storm
Watch for much of the area. Left areas generally S of I 70 out of the
watch...except for the WV/Maryland ridges...as enough warm air is expd to
wrap in ahead of the low to allow for a rain/snow mix or even a period of
all rain. Areas between I 70- and I 80 could see enough warm air
aloft for freezing rain to mix in at times as well. Generally followed a
sref/GFS/ECMWF model blend to work out the details...and used
critical thicknesses/model sounding profiles for precipitation type. Best
potential for greater than 6 inches of snow exists north of pit based
on latest model guidance...though this will be refined over the next
couple of days.

Snow should continue Monday until the upper trough axis shifts east in the afternoon.
Nudged temperatures to the latest colder than seasonal average sref guidance.

&&

Long term /Monday night through Friday/...
a cold...winter pattern will continue for the rest of the long
term. The next best chance for snow showers will arrive late in
the period.

&&

Aviation /19z Friday through Wednesday/...
MVFR ceilings with IFR visibility in snow showers will continue this afternoon. Genl
improvement can be anticipated thereafter as dry advection and subsidence
increases. Surface wind are expected to continue to gust from the west and northwest
at 15 to 25 knots through the day. Further improvements can be
expected as high pressure builds through Saturday morning.

Outlook.../Saturday night through Wednesday/...
widespread restrictions can be expected with Sunday low pressure and
with a Monday cold front.

&&

Pbz watches/warnings/advisories...
Maryland...Winter Storm Watch from late Saturday night through Monday
morning for mdz001.
Wind Chill Advisory from 7 PM this evening to 10 am EST
Saturday for mdz001.
Winter Weather Advisory until 7 PM EST this evening for mdz001.
Ohio...Winter Storm Watch from late Saturday night through Monday
morning for ohz039>041-048>050-057>059.
PA...Winter Storm Watch from late Saturday night through Monday
morning for paz007>009-013>016-020>023-029-073>076.
Wind Chill Advisory from 7 PM this evening to 10 am EST
Saturday for paz008-009-015-016-023-074-076.
Winter Weather Advisory until 7 PM EST this evening for paz074-
076.
WV...Winter Storm Watch from late Saturday night through Monday
morning for wvz001>003-023-041.
Wind Chill Advisory from 7 PM this evening to 10 am EST
Saturday for wvz023-041.
Winter Weather Advisory until 7 PM EST this evening for wvz023-
041.

&&

$$

07/15

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