Scientific Forecaster Discussion
Area forecast discussion
National Weather Service State College PA
239 PM EST Friday Nov 27 2015
a cold front will cross the area slowly tonight and
Saturday...hanging up just south of the state Saturday night. The
front will move back north early next week and is likely to bring
unsettled conditions back to the region through middle week.
Near term /through tonight/...
widespread u50s and l60s across the County Warning Area at 18z...with dewpoint
depressions on the on the order of 12-15f. Very light rain may now
be into Warren County. The front lies from kdtw to kgsh and is
almost parallel to the upper flow...but strong jet maximum over LH and
lower ont will slide east and bring the r ent region of the streak
overhead this evening. Therefore...some light rain is expected to
spread across the northern tier through sunset - but any meas rainfall
will likely not get south of a St Marys-Wellsboro line before
midnight. A few sprinkles will fall down around I-80 by
midnight...but it will take quite a while for the meas rain to
work southward overnight. Mins will be quite mild...especially for southern
towns. The front only gets to about rte 22 by 12z.
Short term /Saturday through Saturday night/...
the front does go slowly to the south but most guidance is now in
agreement that a wave develops along it and pushes across the
central Appalachians Sat night. While the upper support wanes
during the daylight hours on Sat...the wave should reprise the
rainfall across the southern third to half of the County Warning Area. Total quantitative precipitation forecast
through sun am should be around a tenth of an inch in the north to
a third to a half of an inch in the south...with most of that
coming Sat night. Of course there is still some uncertainty with
the quantitative precipitation forecast in the south due to recent waggling north-S of the path/track
of the weak wave. Since the surface reflection of the low pressure is
so weak and the driving force is a fast-moving thing...will top
probability of precipitation out in the 70s. As the wave passes through...it may either
bubble up some light rain into the north - or the low level
moisture could make for some dz. If it gets cold enough Sat
night...some flurries of patchy dz is possible in the northern mountains
maxes on Sat will be much above normal 50s in the south but nearly
normal l40s in the northern mountains Sat night temperatures will dip to the 20s
in the north but hold in the 40s under the clouds/rain in the southern
Long term /Sunday through Friday/...
cold front sags to the south of PA with diminishing chances for
showers across the south. Afternoon temperatures Sunday in the 40s.
Short-wave ridge moves through Sunday night and Monday with clouds
from the next system already moving in Monday afternoon.
Precipitation moves in from the southwest Monday night. Warm air
aloft should keep most of it as rain however as it reaches
northeast toward morning hours there may be some colder areas
below 32 causing some patchy freezing rain for a brief period
Tuesday morning. Warm front moves through Tuesday as the storm
center moves northeast across the Great Lake region. The
associated cold front will then sweep east across PA on Wednesday.
Behind the front expect brisk winds and scattered showers changing
over to snow in the higher elevations and Northwest. Lake effect
snow showers in the northwest will diminish into Thursday as
another short-wave ridge pushes in Thursday and Thursday night.
Friday becomes more uncertain. Models are trending that a storm
system will move across to our south. We can expect south clouds
from this system across the southern zones and a slight chance
that precipitation would work north into the lower Susquehanna
Aviation /19z Friday through Wednesday/...
light rain is moving toward kbfd...but ceiling still pretty high there
and reduction in visby should be limited to MVFR before 5 PM.
Otherwise...mainly VFR conditions early tonight with lots of
high clouds but little middle/low level moisture. Cold front moves
slowly across the area from northwest to southeast tonight and
Saturday. Rain showers should begin around kbfd around sunset. They may
not affect the southeastern terminals until sunrise. Rain will be
light...but dewpoints rising may create areas of lower clouds and
fog. Showers and lower ceilings and fog could linger into Sat...especially
for the southern half of the area.
Sun...mainly VFR - rain possible extreme south.
Monday...no sig weather.
Tuesday...showers west...VFR east.