Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Pittsburgh PA
825 am EDT Tuesday Oct 13 2015
colder weather will persist into the weekend.
Near term /until 6 PM this evening/...
a cold front is expected to cross the region this morning...with a
stratocu layer moving in. A few showers are possible especially north
of I 80 as an upper trough advances across the region.
Temperatures should be near seasonal levels using the latest lamp
Short term /6 PM this evening through Friday/...
continuous troughing and cold advection across the region will
help support a stratocu deck through Wednesday evening. Weak upper
impulses passing through the main trough may bring low chance
showers for the region north of I-80...where better support for
lift is prognosticated and where relative lake enhancement may occur.
Surface high pressure starts to build in Wednesday night as the
main trough slowly shifts east. This will result in a clearing
trend through Thursday night.
An approaching shortwave trough on Friday is prognosticated to support
showers early Friday with the passage of a cold front. Have
maintained chance probability of precipitation for now due to discrepancies between NAM
and GFS of timing and quantitative precipitation forecast.
Temperatures are forecasted to average several degrees below
seasonal levels after making some adjustments to GFS MOS guidance.
Long term /Friday night through Monday/...
broad upper troughing is prognosticated across the eastern Continental U.S. Into
the weekend with reinforcing cold fronts resulting in
progressively colder temperatures...with near freezing temperatures by
the start of the new week. Thereafter...models indicate temperature moderation
under shortwave ridging. The long term forecast was based on a
blend of wpc and GFS MOS guidance.
Aviation /12z Tuesday through Saturday/...
VFR is expected to dominate most of the day although passage of a
cold front will Herald cumulus and stratocu development...and possibly
some showers...better chance for which is anticipated near fkl and
duj. As cold advection intensifies...the stratocu bases should
drop below MVFR thresholds...especially with a crossing shortwave
A surface wind veer to the west can also be expected early this
afternoon as the front encroaches. Gusts of 15 to 20kt can be
expected as mixing improves.
Outlook...Wednesday through Saturday...
restriction potential with MVFR stratocu may linger into early
Thursday as cool flow off the Great Lakes persists.