Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Pittsburgh PA
1204 PM EDT Wednesday Sep 17 2014
dry conditions will continue until the approach of a Sunday cold front.
Near term /through Thursday/...
no major changes were needed for the early afternoon update.
Surface high pressure undr upper eastern North American trough will maintain dry and
cool conditions today...however...slow moving shortwave in northwest flow is
spawning stratocu and cumulus over a wide swath to the west of I 77. That
cloud area is expected to be maintained/reinforced tonight as a weak
front is pulled over the region. In accordance with the latest
models trends...have adjusted upward the near term cloud cover
..which should diminish rapidly aftr daybreak on Thursday as
subsidence increases with decisive passage of the disturbance.
Otherwise...have persisted with the cool near term temperatures.
Short term /Thursday night through Saturday/...
the reinforced surface high will build off the East Coast by Friday with southerly
flow reinitiating warm...relatively moist advection over the upper Ohio
region. This will cumulate in temperatures surging about 5 degrees above
the avgs by Saturday afternoon...although dry conditions will continue until
the apprch of the Sunday cold front.
Long term /Saturday night through Wednesday/...
the apprch of a shortwave/associated cold front on Sunday is expected to
generate the next chance for showers over the region while passage should
surge cooler air back over the region aftr the Saturday warm up.
Models agree that East Coast upper trofg will linger into midweek with northwest
flow off the Great Lakes...but diverge significantly in amplitude
projections of that trough. The long term forecast is thus of
persistence with dry and cool conditions continuing.
Aviation /16z Wednesday through Sunday/...
VFR conditions and light surface wind were maintained through
tonight...although stratocu and cumulus will plague the region at least until
passage of a weak front/upper disturbance on Thursday morning. At moment...it
apprears that cloud cover will be sufficient to preclude significant
fog restrictions for all but the northern terminals.
Outlook...Thursday through Sunday...
the next chance for genl restrictions will come with a Sunday cold front.