Scientific Forecaster Discussion
Area forecast discussion
National Weather Service State College PA
152 am EDT Wednesday Sep 3 2014
high pressure will build along the East Coast the rest of this
week. A cold front will likely push south across the region by
Near term /until 6 am this morning/...
cold front stalling out just south of the Mason Dixon line early
this morning. Radar loop at 05z showing the last of the showers
have dissipated across the southern counties. However...weak
shortwave tracking east from the Ohio Valley...combined with
lingering moisture near frontal boundary...could still produce an
isolated -shra along the S tier early this morning...so have included
a 15 pop S of the Turnpike through 09z.
Low level moisture trapped beneath subsidence inversion and forced
to ascend the alleghenies will result in stratus/fog across the West
Mountains early this morning. Further east...clearing skies...a light
wind wind and wet ground will likely lead to patchy fog toward
dawn. Temperatures on track to bottom out from the m50s over the northwest
mountains...to the m60s across the lower susq valley.
Short term /6 am this morning through 6 PM Thursday/...
model soundings suggest low clouds/fog will take until around 14z to
mix out over the West Mountains for the rest of the day...high pressure and
associated drier air mass over the area will supply mostly sunny and warm
conds. Ens mean 800 mb temperatures near 15c should support maximum temperatures from the
m70s northwest mountains to the m80s in the susq valley.
It will continue fair tonight with little more than patchy late
night fog as the only real sensible weather.
As high pressure slips off the East Coast Thursday...return southerly flow
will draw warmer and slightly more humid air into the region.
As subtropical high builds off the southeast coast...models show a shortwave
tracking along it/S north periphery across the east Great Lakes. In
general...temperatures aloft look warm enough to suppress convection...but
can/T rule out an isolated rain showers over the mountains of central PA as
shortwave approaches late in the day.
Long term /Thursday night through Tuesday/...
subtropical ridge centered over the Carolinas will be suppressed
by shortwave energy and moderate-intensity surface cyclone tracking
northeastward from the northern High Plains across western Ontario into northern Quebec
Thursday through Sat. Its trailing cold front remains the focus for precipitation
heading into the weekend with continued uncertainty in the southeastward
frontal progression. A slower trend may be emerging in the 12z
GFS/gefs with its frontal zone aligning closer with the European model (ecmwf)/Gem
by 00z sun. Maximum probability of precipitation shift from northwest to southeast over the County Warning Area from 00z Sat
to 00z sun. Ahead of cdfront...temperatures are likely to peak on Friday
with mean 850 mb temperatures +18-20c supporting widespread highs 85-90f.
The next question concerns how quickly the front clears southern PA on
Sunday with model data suggesting the upper level front hangs
back along the applchns/mid-Atlc Piedmont...as energy is sheared
northeastward through the northern New England and Canadian Maritimes and flow
aloft becomes oriented more westerly. Mean precipitable water fields show drier
air spreading into the region from the northwest behind the front as
high pressure becomes established in the northeast by early next
week. Therefore expect temperatures and probability of precipitation to trend lower during the
Aviation /06z Wednesday through Sunday/...
cold front southeast of the area now.
Most areas now VFR...but IFR across the higher mountains
to the west.
Some potential still for fog...but a slight breeze may
limit fog some.
After about 14z...looking at a fine late Summer day...with
mainly clear skies.
Maybe some fog Thursday morning...then another decent
day...as high pressure moves east of the area.
Friday...mainly VFR. Chance of PM thunderstorms west.
Sat...VFR/MVFR with scattered shwrs/tstms. Cold frontal passage.
Sun...am fog...otherwise VFR.
short term...Fitzgerald/la corte