Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Pittsburgh PA
242 PM EDT Thursday Oct 30 2014
low pressure will cross the region Friday and Saturday with
Near term /until 6 am Friday morning/...
with cool air aloft...stratocu is expd to continue into the
evening...though these should dcr some Erly this evening as weak high pressure
builds in. Some isolated light showers North-East of pit should dspt as well with
the building high. Clouds will increase again later tonight ahead of the next advancing
shortwave. Low temperatures should be a little below the seasonal avgs.
Short term /6 am Friday morning through Sunday/...
a deepening upper trough and its associated surface low will advance across the Great
Lakes Friday with increasing shower chances Friday. The deep upper trough will remain across
the eastern Continental U.S. Sat with a moisture swath and Omega across much of the
region...keeping chances for precipitation. Colder air is expd to begin to move
in behind the initial surface low as north-NE flow develops Friday night into Sat.
Critical thicknesses and sounding profiles indicate this could
allow for a little snow to mix in with rain showers at times Sat
morning...but a warm boundary layer should limit this potential and prevent
any accums outside of the ridges southeast of pit. In the ridges...experimental a
gradual change over to mainly snow Sat in the highest elevations. Generally
experimental a couple of inches of snow in the highest terrain in grassy
areas before the precipitation begins to dmnsh Sat night. The upslope
component is limited with north-NE flow...and moisture begins to dmnsh by
the time northwest upslope flow develops.
Building high pressure and dry weather is prognosticated for sun. Temperatures should average
below seasonal levels through the weekend.
Long term /Sunday night through Thursday/...
used HPC guidance for this period which was based on gefs/ecens means.
A cold Sunday night will be followed by moderating temperatures...with
readings close to seasonal by Tuesday as a flat upper ridge is
forecast to move through. Another...much more shallow trough is
projected for a middle week...with Promise of an unsettled end to the
Aviation /19z Thursday through Tuesday/...
stratocu blanket will continue to plague upper Ohio terminals into this
evening...but genl VFR/high end MVFR will be predominate. Othrwise...light
surface wind will veer to the SW and S late tonight as upstream shortwave
advns...but genl condition deterioration is not anticipated with
that system until well aftr daybreak Friday.
Outlook.../Friday night through Tuesday/...
widespread restrictions are expected by Friday evening as deepening low
pressure shunts a broad moisture swath over the upper Ohio region. Ensuing
upsloping cold advection will then maintain shower and stratocu potential
until surface high strengthens on Sunday.