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Area forecast discussion 
National Weather Service Pittsburgh PA
338 PM EST Sat Jan 31 2015

Synopsis...
low pressure will bring wintry weather Sunday into Monday.

&&

Near term /through tonight/...
high pressure will continue to bring dry weather into the evening. A digging upper
trough and developing surface low pressure will begin to spread snow into the region lt
tonight. More on this in the short term section. Accumulations by
morning should be generally less than an inch as the precipitation will just be
starting. Overnight lows were adjusted to near the latest sref numbers.

&&

Short term /Sunday through Monday/...
that digging upper trough and surface low will continue to advance out of the
Midwest through our region Sunday Monday. Models have shifted the track of
the surface and 850 mb lows further north...shifting the focus for heavier
snow north of pit. A low level jet is prognosticated to develop along with deep moisture
and increasing Omega with warm advection later sun into Sun night...when the
heaviest precipitation is expd. Along with that warm advection...a changeover
to mainly rain is expd S of I 70...with a mix of snow...sleet and
freezing rain north to around pit. A brief changeover to all rain is possible as
well. North of I 80 should stay cold enough for all snow. GFS was
farthest north with the surface and 850 mb lows...and seemed too aggressive
with the warm advection. Opted for the colder NAM/European model (ecmwf) solutions which
allows for a little more gradual of a forecast shift. Relied on critical
thicknesses and model sounding profiles for precipitation type forecast.

Issued a Winter Storm Warning for areas north of pit where 5 to 10
inches of snow are expd. From near pit and S to I 70 issued winter weather
advisories for 2-5 inches of snow and a potential for a wintry mix.
Watches are no longer in effect as areas S of the PA border...even
in the ridges...should change over to mainly rain. Freezing precipitation is possible
especially in Garrett County but held off on any addnl headlines at this time.

Wrap around snow behind the exiting low is expd Monday but only around an
inch or two of addnl snow is expd.

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Long term /Monday night through Saturday/...
only change to extended was to speed up frontal passage Wednesday
and bump up probability of precipitation. No other changes as much colder air pours in
behind the front as a Stout high pressure centers overhead.
Temperatures expected to be well below average from middle-week through
the end of the period.

&&

Aviation /20z Saturday through Thursday/...
general VFR until the pre-dawn hours Sunday when conditions will
deteriorate to IFR ceilings and snow as low pressure advances east.
Expect IFR from around 09z Sunday at kzzv to quickly spread to klbe
and kduj 12-14z and remain throughout the end of the taf period..

Outlook.../Sunday night through Thursday/...
widespread restrictions can be expected into Monday as a low
pressure system crosses the region. Next chance for widespread
restrictions will be with a Wednesday cold front.

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Pbz watches/warnings/advisories...
Maryland...none.
Ohio...Winter Weather Advisory from 4 am Sunday to noon EST Monday
for ohz039-040-048>050-057>059.
Winter Storm Warning from 4 am Sunday to noon EST Monday for
ohz041.
PA...Winter Weather Advisory from 4 am Sunday to noon EST Monday
for paz021-029-073-074.
Winter Storm Warning from 4 am Sunday to noon EST Monday for
paz007>009-013>016-020-022-023.
WV...Winter Weather Advisory from 4 am Sunday to noon EST Monday
for wvz001>003.

&&

$$

07/10

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