Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Pittsburgh PA
1232 PM EDT Monday Jul 6 2015
an upper level disturbance will bring showers today. Unsettled
weather will continue through much of the week as a cold front
approaches and stalls across the region.
Near term /until 6 PM this evening/...
with noon update...have made additional changes for hourly
temperatures. Cloud cover has not held down temperatures as much
as expected...even in the east where temperatures were expected to
be cooler...and have brought temperatures back up a couple of
Coverage of showers and thunderstorms will continue to increase
this afternoon with upper low overhead. With very weak steering
flow...any showers that develop will be slow moving in nature and
could produce rainfall rates of one inch per hour. Just recently
issued a Flood Advisory for northern Allegheny County...but
considering one hour flash flood guidance...these rainfall rates
should not be an issue outside of urban areas.
Short term /6 PM this evening through Thursday/...
the upper low is prognosticated to open into a trough and exit later
tonight through Tuesday morning...with decreasing precipitation chances.
Another shortwave and associated cold front is prognosticated for a late
Tuesday/Tuesday night approach and passage with showers and
thunderstorms likely. Model prognosticated shear and instability are not
impressive...though model soundings show some dry middle level air
across the region which could allow for gusty winds in any
The front is prognosticated to stall across far southern PA/northern WV
Wednesday as another shortwave advances along it...keeping
showers/storms for areas mainly south of I 80. Another shortwave
and surface low is prognosticated to bring the front further north
Thursday with continued precipitation chances. Generally followed close
to the GFS/European model (ecmwf) solutions...with the NAM being a slower outlier.
Seasonally warm temperatures are expected to continue using a
blend of raw GFS numbers and GFS gridded MOS.
Long term /Thursday night through Monday/...
frontal boundary will waver across the region through the period
as shortwaves move east in relatively zonal middle level flow. With
individual shortwaves hard to time have kept chance probability of precipitation through
the period. Temperatures close to wpc forecasts which seemed a good
Aviation /18z Monday through Saturday/...
an upper low over the area will result in scattered showers and a
few thunderstorms over the course of the day. Latest model
soundings suggest ceilings should remain at or above 3kft...however...MVFR
ceilings/visible will more than likely be observed during heaviest
precipitation. VFR overnight...with a slight chance of fog before
Outlook.../Tuesday through Friday/...
periodic restrictions are possible through the period with
several crossing disturbances.