Scientific Forecaster Discussion
Area forecast discussion
National Weather Service State College PA
906 PM EST sun Dec 28 2014
colder and drier air will filter into the area over the next
several days...with temperatures returning back to seasonal
normals...which will feel quite cold considering how warm it has
been recently. The next significant chance for precipitation will
not be until next weekend.
Near term /until 6 am Monday morning/...
despite overall middle level drying with west-northwest flow. Low level
trajectory remains across the Great Lakes leaving a strato cumulus deck
below an inversion and upslope into the mountains. Some breaks in
the clouds are expected Lee of the Allegheny Front. A weak
disturbance will pass primarily to our north tonight but may be enough
to squeeze out some flurries in the upslope areas of the northwest
mountains. Temperatures noticeably cooler tonight with readings in
the northwest zones already below freezing with southeast zones reaching there
Short term /6 am Monday morning through 6 PM Monday/...
temperatures should be below freezing for all but the SC/southeast by sunrise
Monday. But these numbers are still quite /8-10f/ above normal
mins for this time of year...despite only light northwest wind and decent
cold air advection. No precipitation and light winds for Monday. Downsloping should
create pt/MO sunny conditions in the southeastern half of the area. But
high clouds streaming across the S may dim the sunshine.
Temperatures will be almost spot on normals - quite a bit cooler
than the past several days.
Long term /Monday night through Sunday/...
as mentioned in previous discussions...a wave develops south of
the area and tracks northeast. More confidence that impacts/precipitation
from this system will stay south and east of the County Warning Area Monday night
and Tuesday...with a few flurries possible across The Laurels on Tuesday.
High pressure will build over the middle of the country by midweek
and slowly drift off the East Coast by the end of the
workweek...bringing an extended period of fair weather to the
forecast area. However...waves of colder air diving down from the
north will help temperatures will return to normal for the last week
of December. Cooler air and breezy conditions will result in single
digit wind chills over northern and western parts of the County Warning Area as we
ring in the New Year.
Gefs and long range guidance show the first significant storm of
2015 developing for next weekend. Storm track will be critical as to
what type of precipitation falls across the area. Right now...the
GFS tracks the low west of PA bringing another shot of mild air back
into the state with rain likely the most dominant precipitation
type. In contrast...the European model (ecmwf) brings the surface low south and east
of PA which would result in colder air and a more mixed bag of
precipitation types. The salient point in this is that there is
still much uncertainty with this system...details will continue to
change as the week progresses and model forecasts align.
Aviation /02z Monday through Friday/...
cooler and drier air continues to move into the region behind
cold frontal passage earlier today. This has lead to improving conds with
VFR at all airfields except kjst. Kjst has been making some
improvements through the evening hours before dropping back down.
Expect IFR ceilings to continue through midnight before slow
improvement to MVFR ceilings overnight.
A secondary trough moves into/through the northern mts late this
evening and could touch off isolated shsn or some patchy fzdz vicinity
kbfd...but this would be very brief and not Worth a mention in
the tafs at this point. Also...the ceilings could lower at kbfd more
toward morning as the subsidence inversion lowers and squeezes the
cloud deck lower. Elsewhere...VFR is expected through Monday.
High pressure centered over the plains will stretch far to the
east and allow northerly winds and dry air to last for the next
few days. A few flurries off the lakes or on upslope flow into jst
will be the only possibilities of precipitation until next weekend.