Scientific Forecaster Discussion
Area forecast discussion
National Weather Service State College PA
306 PM EST sun Dec 28 2014
colder and drier air will filter into the area for 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 midnight tonight/...
lots of clouds remain over the region this afternoon despite
drying west-northwest flow. Low stuff is starting to break up on the Lee side
of the Allegheny Front but higher clouds still streaming over from
the W/SW. Scattered showers will linger in the far S through sunset as
a very weak wave rolls just to the S of the state. Any snow in the
very highest elevations of The Laurels is going to be negligible
due to warmer- than-freezing temperatures until late afternoon. A thin coating
may accumulate but hardly enough to mention. Temperatures steady now
across the entire region...but will start to fall shortly.
Short term /midnight 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. Any showers should be south of the state...except for the
possibility of shsn or even a patch or two of fzdz over the northwest
tonight. But the shsn/fzdz would be widely scattered and no accums are
expected at this point. However...any fzdz...if it does
develop...could make a slippery morning drive in the far northwest/northern
tier. No advisory necessary at this point due to the very low probability of
occurrence. We should enjoy 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 /20z Sunday through Friday/...
jst is improving very slowly but still in the soup on upslope
flow with moisture and lower clouds upstream all the way into Northern
Ohio. Therefore...improvement there will continue to be slow this
evening. Bfd also will deal with high-IFR and low-end MVFR for
the rest of the daylight. A few showers may nudge back north of
the Maryland border and affect the lns/MDT vcty later this afternoon/early
evening. But no reductions are forecast at this point. A secondary
trough moves into/through the northern mts this evening and could touch
off isolated shsn or some patchy fzdz...but this would be very brief
and not Worth a mention in the tafs at this point. Also...the ceilings
could lower there and also at jst once more toward morning as the
subsidence inversion lowers and squeezes the cloud deck lower. VFR
should dominate to the southeast of the typical aoo-unv-ipt line. Ceilings
at those three sites will dance around fl030 for the at least
early this evening.
High pressure 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.