Area Forecast Discussion
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FXUS61 KPBZ 071600
Area Forecast Discussion
National Weather Service Pittsburgh PA
1100 AM EST Wed Dec 7 2016
Building high pressure should maintain dry weather today. A
Thursday cold front will bring much colder temperatures and snow
shower chances to end the work week.
.NEAR TERM /THROUGH TONIGHT/...
Building high pressure should maintain partly cloudy skies across
the area this afternoon. A shortwave and surface trough should
cross the area overnight with an increase in clouds, though with a
lack of deep moisture available little or no precip is expected.
Temperatures should average near seasonal levels.
.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
An upper-level low will advance east into Quebec Thursday, allowing
much colder air to wrap in behind, invading our area from the west.
Very little moisture exists along the mid-level cold front, so
initial precipitation chances will be minimal through Thursday
afternoon, but a slight wind shift will bring lake-effect and
upslope snow that could extend into the early weekend.
Although cold advection will be ongoing, the coldest air will pour
in later Thursday afternoon with a mid-level trough. This will
steepen lapse rates through the mid-levels and increase the boundary
layer height. Veering winds behind the trough axis will seep Great
Lakes moisture in across the northern 1/3 of the forecast area,
eventually extending southward into the Ridges. Deep northwest flow
will spread snow showers initially confined to our northern reaches
southward, nearing the Pennsylvania Turnpike Friday afternoon. Snow
showers will be ongoing through much of the day Friday for the
northern 1/3 as well as into the Ridges. These areas stand to see
the best chance of accumulating snowfall, albeit over a fairly long
duration. For now, will carry a mention of accumulating snow in the
HWO for these counties. With a less favorable wind setup and less
moisture availability for most of the event, eastern OH, northern WV
(outside of the mountains), and much of southwestern PA should see
little to no accumulation.
The shot of much colder air will hold temperatures 5-10 degrees
below the averages.
.LONG TERM /SATURDAY THROUGH TUESDAY/...
Surface high pressure will briefly settle over the area
Saturday, bringing an end to any remaining light snow showers. Drier
weather will remain fleeting, however, as zonal flow aloft will
quickly advance the next system into the lower Great Lakes. Models
currently having a difficult time latching onto this system, leaving
the track in limbo. The track of the low will play a vital role in
determining the level of warm air advection and subsequent
precipitation types Sunday into Monday. Regardless of the exact
path, the setup is favorable for tapping into Gulf moisture to
spread along the trailing boundary. Superblend was largely utilized
for this system, including the inclusion of likely PoPs Sunday
After the early week system, models differ slightly on smaller
disturbances through the upper-level pattern. One thing that is
fairly certain, however, is that the cold air will stay through next
week, continually re-enforced by mean northwest flow aloft. Middle
of next week should feature temperatures that are well-below
.AVIATION /16Z WEDNESDAY THROUGH SUNDAY/...
Patchy MVFR CIGs will improve to VFR through the day, and
continue through tonight. Expect west to southwest winds under 10
KTs ahead of an approaching cold front through Thursday morning.
Periodic restrictions in snow showers are likely for the rest of
the week as a strong cold front sweeps the region Thursday, with
cold advection through the weekend.