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

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


Near term /until 6 am Saturday morning/...
a weak stationary surface boundary and diurnally driven
instability should continue scatterd to numerous showers and
thunderstorms north of I 80 this evening. Expecting mainly
isolated showers/thunderstorms south of the boundary where less
instability is seen on mesoanalysis with warmer mid level

Increasing cloud cover and minimal shower chances should continue
overnight 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 /21z Friday through Wednesday/...
general VFR is forecast through the evening with exceptions for
isolated to scattered convection which is more likely to affect
fkl and duj due to the presence of a weak front and outflow
boundaries from previous convection.

Given the frontal position and abundant low level moisture, expect
the return of some fog and stratus, albeit not as extensive and
long lasting as this morning.

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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