Area Forecast Discussion
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FXUS61 KPBZ 220552

Area Forecast Discussion
National Weather Service Pittsburgh PA
1252 AM EST Sun Jan 22 2017

The run of mild weather will continue through midweek. Rain will
move back over the area later today and continue into Tuesday.


No major changes to the overnight period. Some minor adjustments
to PoPs and clouds. Temperatures have been refreshed with a blend
of hires guidance.

Still seeing the models trying to get the final solution for the
upper level low which will be the main player in our weather
through early Tuesday. Even ensemble data is struggling to come to
a consensus on the path and speed of the upper level low.

Have backed off on the timing of the showers today as ensembles
have slowed the eastward movement of the system and are
advertising a track that is a bit further south. Operational
models, including the hires variety, agree with this idea, as qpf
only reaches Southern West Virginia by this afternoon. This is
mostly due to the aforementioned more southern path of the upper
low and also the further suppression south of the main jet
swinging around the low. Additionally, the first upper level wave
that is pushing the showers northward, splits from the main flow
and heads eastward into the still prevalent, although weak,
eastern ridge. Have continued to lean away from the NAM op
solution, as it has been an outlier during the entire evolution of
the system.

Today`s PoPs will mainly cover the southern third of the region
and will begin the process of overspreading these locales during
the afternoon.

Temperatures again will be well above normal.


Model depictions of the cutoff low pressure set to dig toward the
Upper Ohio Region, have deviated from previous days solutions
with a more westward track of the center. Increasing ascent via
deformed flow and warm advection with increased moisture through
the mid levels all support escalating precip probabilities to
categorical numbers tonight and into Monday.

With the northern branch of split flow holding colder air north and
west of the region, and with warm advection into the mid levels
of the cutoff, this looks to remain a rain event. The NAM again
deviates from other model solutions and develops sub-zero air
over the region at the 850mb level despite moist advection and an
otherwise warm column. Will continue to move away from the NAM
solution. This choice is also further supported when viewing the
plumes from the SREF and GEFS model. If colder air does make it
into the area, it would likely be late Monday night, when most of
the precipitation will have exited the area.

QPF was progged using a RFC/WPC blend for the period. An inch to
inch and a half is anticipated for the early week with limitations
imposed by low pressure progression and mid level dry slotting.

Relative warmth will continue, although the diurnal temperature
spread will be restricted by clouds and precip.


By the beginning of the long term, upper level ridging will take
over, but will not last long as the next system quickly movew
across the northern plains/upper midwest and across the northern
Great Lakes on Wednesday. Scattered showers will cross the area
Wednesday and above normal temperatures will remain.

A pattern change is expected to ensue on Thursday, with a return
to January temperatures that will remain through the remainder of
the long term. Snow showers will return as well.


A passing shortwave is bringing a cluster of showers and even a
few embedded thunderstorms to northern Ohio. Most of this activity
will remain off to the northwest, but a few light rain showers
will remain possible overnight, with mostly VFR conditions
continuing. Cannot rule out some light valley fog as well, with
little to no dense fog anticipated due to cloud cover.

VFR conditions will continue through most of Sunday with mainly
mid-level clouds and light wind. The approach of another
shortwave after 00Z results in a deterioration to MVFR conditions
in rain. Winds will pick up out of the east and gust to 20 knots
as well.

Restrictions are likely through Tuesday with slow moving low
pressure, and again with a Thursday cold front.




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