Area Forecast Discussion
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FXUS61 KPBZ 051032

Area Forecast Discussion
National Weather Service Pittsburgh PA
532 AM EST Mon Dec 5 2016

An unsettled weather pattern will continue through the week, with
rain possible again Tuesday. Much colder air and snow showers will
arrive by Friday.


Shortwave continues to pivot eastward this morning, with drier air
aloft advecting over the region supporting some drizzle. Have
adjusted the forecast the reflect this, with quiet conditions
expected for the rest of the day. Also, as temperatures across
the entire region have gone several degrees above freezing in
southwesterly flow, have cancelled the winter weather advisory
for the ridges. Some cold advection this morning may support a few
flurries, as some of the model profiles show saturation deep
enough for a few flakes, but overall not expecting much today.

Despite high pressure settling overhead, cloud cover should limit
temperatures to just below seasonal averages.


The next system, currently back near southwest Texas this morning,
will lift northeastward with the help of a digging system of the
northern Plains. Plenty of moisture will stream northward from the
Gulf with this system, but much of the guidance has a secondary
low developing along the east coast, which will rob some of this
energy from us. Regardless, we are expecting a surge in warm
temperatures aloft to support mainly rain across the region with a
brief mix at onset possible, especially north of Pittsburgh. This
may be another good set-up for some icing in the ridges, much
like last evening, as cold air is reinforced with in southeasterly
upslope flow. Have mentioned this threat in the hwo and will let
the next shift analyze the hi res model data to get a better
handle on duration of the event.

With the decent model consensus and progged lift, have maintained
the categorical PoPs areawide through Tuesday night. A changeover
to snow is possible late Tuesday night/Wednesday morning but with
westerly flow for much of Wednesday, and subsidence aloft
conditions should dry out before the more notable cold air
filters southward for the end of the week.


The active weather pattern continues as a strong cold front
moves across the region on Thursday, bringing the coldest air of
the season so far. Virtually all snow is expected with the
passage, although there will be little accumulation associated
with the boundary itself. Cold advection snow showers are then
expected to continue through Friday night, ending as flurries
north of Pittsburgh Saturday morning. Best accumulation chances
during this period will be along/north of I-80 and along the
ridges. Temperatures may recover somewhat thereafter, such that
the next system Sunday into Monday may have more rain involved
than snow.


Some patches of drizzle will remain at 12Z, but this should taper
off for the most part by mid-morning.  MVFR ceilings will linger
through the morning as low pressure pulls away and gusty west to
northwest winds continue.  Building high pressure this afternoon
will lift ceilings back to VFR and allow the wind to diminish to
under 10 knots.

VFR conditions will then continue tonight as the high crosses.
Clouds will be on the increase ahead of the next fast-approaching
system from the southwest.  Some precipitation may show up near the
Mason-Dixon Line just prior to 12Z Tuesday.

Restrictions are likely Tuesday and Tuesday night as the next low
pressure system crosses.  A strong cold front will bring more
restrictions by Thursday.




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