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Area forecast discussion 
National Weather Service Pittsburgh PA
858 PM EDT Friday Jul 29 2016

a series of weak disturbances will keep periodic shower and
thunderstorm chances in the forecast through the weekend.


Near term /until 6 am Saturday morning/...
scattered showers and thunderstorms resulting from diurnally
driven instability and a nearly stationary surface boundary across
the area should continue to diminish this evening. Increasing
cloud cover and minimal shower chances should continue overnight
however as low pressure approaches. Lows should average a few
degrees above seasonal levels.


Short term /6 am Saturday morning through Monday/...
a weakly coupled upper jet structure looks to work across the area
on Saturday with the continuation of a moist and unstable boundary
layer in place. Increasing upper divergence through the day will
allow for shower and thunderstorm development over the area on
Saturday. Mid- level moisture flow from east-west will continue to lift
north of the area as the system digs over the region Saturday
night, resulting in the best chances of showers and thunderstorms
slowly translating nneward.

Another wave will dig into the base of the upper level trough by
Sunday afternoon. This will bring another increase in the chances
of shower and thunderstorm activity across much of the area as
the mid-levels start to nominally cool. It will also start to
usher in drier mid and upper level air as it does so. This will
allow for the reduction in the chances of precipitation by Monday
as cooler nwerly flow becomes entrenched over the area.


Long term /Monday night through Friday/...
surface high pressure will build into the area from the western
Great Lakes Monday night into Tuesday. This will allow the area to
remain in cooler northerly flow even as subsidence builds. A dry
forecast will thus be maintained through mid-week.

Ridging at all levels of the atmosphere should thereafter increase
from mid-week Onward as amplification of the pattern is evident on
basically all guidance over the upper Mississippi Valley and
northern Great Lakes during the second half of the week. This
ridge and resultant low level thermal ridge should start to flop
over toward our area by Friday, which at this point looks to be
the warmest day of the next week or so, when temperatures should
push again well above normal.


Aviation /01z Saturday through Wednesday/...
general VFR is forecast through the evening with exceptions for
isolated convection which will wane with the sun. Mention will be
reserved for amendments given the declining coverage and questionable
location of cell initiation.

Given the frontal position and abundant low level moisture, expect
the return of some fog on Saturday morning, although mid level
cloudiness is expected to alleviate a widespread IFR threat. Will
hedge from previous pessimistic forecast with an MVFR mention.

Outlook /Saturday night through Wednesday/...
broad upper troughing should maintain periodic shower and thunderstorm
restriction potential through Monday.


Pbz watches/warnings/advisories...



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