Area Forecast Discussion
Issued by NWS

Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

FXUS61 KPBZ 190928

Area Forecast Discussion
National Weather Service Pittsburgh PA
528 AM EDT Wed Oct 19 2016

Scattered showers remain possible along a stalling front today. A
wave of low pressure along the front will bring much better rain
chances tonight into Friday. Much cooler air arrives by the end of
the week.


Update to freshen up PoPs and sky cover with minor changes
overall.  Forecast generally on track.

Previous discussion...

With loss of the meager upper support the front had,
precipitation coverage has waned to a couple of broken lines along
and ahead of the front. Expect this decreasing trend to continue
with time as the boundary slowly sags towards its resting place
near the Mason-Dixon line later today. Have minimal PoPs near the
front by late morning across the far south. Expect some low clouds
to linger behind the front for a time, with mixing bringing
improving conditions by midday.

Modest instability is expected this afternoon ahead of the front,
bringing isolated to scattered showers across the far south.  Cannot
rule out an isolated thunderstorm as well.  Most other locations
will see scattered to broken cumulus.  Temperatures will remain well
above normal with no cool push behind the front, although still
several degrees cooler than Tuesday.

A wave will develop along the front across the lower Ohio Valley
and begin to push northeast tonight as mid level troughing
intensifies over the Plains. This will begin to push moisture
back in to our area, particularly the northern and western
portions of the CWA. Models indicate that the moistening process
will be a bit slower than previously progged, but an axis of
0.25" or greater rainfall is still expected along and north of a
ZZV-DUJ line, where the potential for best frontogenetic forcing
lies in juxtaposition with PWAT values of around 1.5 inches. This
is where likely/categorical PoPs lie as well, with lesser chances
to the south and east. Temperatures will continue to run well
above normal.


A wave of low pressure is still progged to develop on the front
and further increase shower chances Thursday into Friday as a
mid/upper trough over the midwest amplifies. Models have come into
better agreement on timing and strength of developing surface low
pressure, so likely to categorical POPs were maintained for the
period. Still seeing some differences in solutions as Friday rolls
around, both at the surface and upper levels. Nam remains the
slower solution, as it develops a deeper surface wave in response
to a more dynamic upper level trough. Will not stray too far from
previous forecast as the NAM upper level solution is an outlier in
comparison to ensemble data.

Short term temperature will vary considerably with the meandering
front. Expect 10 to 15 degrees above average warmth Thursday,
quickly falling on Friday under strong cold air advection. A
detailed model blend was used for Friday`s temperatures.


Much cooler temperatures are expected over the region through the
weekend, as upper level troughing develops over the Eastern CONUS.
Scattered showers will remain in the forecast through Saturday as
cold advection continues and shortwaves in northwest flow traverse
the area. Dry, but seasonably cool conditions are anticipated as
high pressure builds for the start of the new work week. Slightly
modified Superblend guidance was used for the extended period.


Front has dropped south of PIT and will continue to sag south
until stalling out near the Mason-Dixon line later this morning.
Ceilings generally VFR or MVFR with small pockets of IFR still
possible into mid morning, especially at DUJ. Scattered light
rain showers will continue to accompany the boundary. Ceilings
will begin to lift past 14Z once daytime heating begins, and VFR
should be reestablished by midday.

VFR will continue into the evening.  Moisture begins to return as
a wave forms along the front to the southwest. Ceiling will drop
again towards MVFR late tonight as more numerous rain showers
develop, especially west of PIT. IFR may make a return to FKL/DUJ
at least by 12Z.

Periodic restrictions are expected during the latter half of the
week as a series of troughs cross the region.




$$ is the U.S. government's official web portal to all federal, state and local government web resources and services.