Area Forecast Discussion
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FXUS61 KPBZ 202105 AAA

Area Forecast Discussion...UPDATED
National Weather Service Pittsburgh PA
505 PM EDT Wed Mar 20 2019

Dry weather will come to an end as the next system brings light
rain Thursday. Rain and snow showers will be possible Friday
before a drier weekend.


Current forecast in good shape. Minor adjustements were made to
cloud cover and temperatures.


A southern stream shortwave will approach the area out of the
midwest as another drops south out of the Great Lakes...and a
third transitions up the east coast. Guidance shows these
features all eventually phasing with a large part of the
forecast area under overall subsidence sandwiched between
relative lows. This should slow onset of precipitation
overnight...until a couple hours before sunrise.

Precipitation will be relatively light with a quarter inch of
rainfall expected through Thursday evening. Many locations will
likely see less than half of that.

Another series of shortwaves within deep east coast troughing
will rotate through late Thursday night into Friday. Cold air
advection following the first trough will allow the thermal
profile to support snow as the primary ptype for much of the
area as these shortwaves rotate across. However, column
moisture will be on the light side so heavy snow is unlikely.
Rather, stratiform light snow is probable in the early portions
of Friday. This precip may be mixed with rainfall in areas south
of Pittsburgh and lower in elevation.

And then, per usual for the Allegheny Plateau and Mtns, northwest
flow in wake of any system means a chance of precip within a broken
stratocu deck. Temperatures on Friday may be too marginal for snow,
especially if the sun manages to shine through the broken strato
deck, at least in the southern zones. Snow showers will
gradually decrease in coverage late Friday, eventually ending in
the mountain regions by dawn Saturday. Only very light snow
totals are expected for the majority of the CWA. The highest
elevations along the Allegheny Front may see upwards of a couple
inches through the period.


Temperatures will moderate a bit over the weekend as the deep
eastern CONUS troughing progrades into the Atlantic. NW flow
aloft will flatten with approach of a shortwave ridge.
Conditions will remain mostly dry though a few quick passing
shortwaves on the NW periphery of our area may enhance cloud
cover and a few brief showers in what will largely be a dry

The next chance for precipitation will come Monday as southern
stream energy interacts with a northern stream shortwave. However,
global model solutions differ on timing and placement so will hold
off on details and go with a general blend in the forecast


VFR conditions continue through much of the TAF period. Clouds
will begin to lower and thicken this afternoon as a mid-level
shortwave approaches. Light rain will encroach KZZV around 06z,
but MVFR conditions not expected to develop until the later
morning hours. The rain and eventually lowering to MVFR cigs
will shift slightly east through the day Thursday, with
increasing confidence of rain at KPIT. However, given the
orientation of the system, it is becoming increasingly
unlikely to reach areas along the eastern ridge line until late

Flight restrictions are likely to continue through the end of
the week with another disturbance bringing rain/snow Friday. A
return to VFR conditions likely by Sunday.




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