Scientific Forecaster Discussion
Area forecast discussion
National Weather Service State College PA
1219 am EST sun Mar 9 2014
High pressure will build into the area on Sunday...followed by
northwest flow with a series of clipper systems passing to the
north early next week. A late-winter storm system will likely
impact the area Wednesday into Thursday.
Near term /until 6 am this morning/...
Cold front has cleared my southeastern zones with just some spotty light
rain or snow sliding across in its wake.
Light precipitation will gradually shift south of the PA/Maryland border and
eventually dissipate as the boundary layer moisture axis slides
south of the Mason Dixon line after 09z. Min temperatures will range from
the middle to upper teens northwest to the lower 30s southeast.
Short term /6 am this morning through 6 PM Monday/...
could see some low clouds hanging tough over The Laurels in the
morning..as moisture ascending the higher elevations via weak upslope
gets trapped under subsidence inversion. However expect a dry but
colder day overall with increase middle-high clouds later sun into Sun
night due to low-middle level warm air/Theta-E advection crossing the Great Lakes in
advance of clipper system approaching the upper Great Lakes.
Long term /Monday night through Saturday/...
frontal boundary sags southward Monday into Tuesday as a clipper system
in northern stream slides eastward just north of the Canadian
border. Moisture and dynamics not very impressive...but enough to
add low probability of precipitation to mainly northern counties for early week. Temperatures
actually rise as this system slides by with westerly flow
advecting in warmer temperatures from the Midwest.
Midweek still looking unsettled as a cutoff low over Texas on
Monday gets absorbed into sharpening trough pushing toward the
East Coast. European model (ecmwf) and GFS suites still indicate a gradually
deepening surface low to track eastward across middle Atlantic region
/before more impressive deepening as it slides off the East
Coast/. Ec still developing a deeper trough...which results in a
more impressive surface wave. The GFS is weaker...flatter and a
If the European model (ecmwf)/gefs solutions end up verifying...heaviest precipitation
occurs during the day on Wednesday...with warmest 850mb temperatures...
suggesting this could be primarily a rain event across southeast
counties with a wintry mix further north and west...especially
later in the event Wednesday night into Thursday as colder air gets dragged
down from the north. But precipitation rates lighten up considerably by
Northern stream drives colder air into PA on Thursday...bringing the
chilliest day of the week as 850 mb temperatures drop below -15c with a
noticeable breeze. Highs will be 10-15f below normal...and likely
feel even chillier.
Cold spell will be short-lived though as warm advection brings
moderating temperatures for Friday into the weekend. Sat and sun
could see temperatures slightly above normal if persistent trough over
the eastern half of country flattens a bit as prognosticated. But no
large-scale warm up is on the horizon just yet.
Aviation /05z Sunday through Thursday/...
big aviation concern late this evening will be low ceilings/visibilities at
kjst from a period of snow in associated with a weak cold front
pushing southward from the lower lakes. Downsloping west-northwest flow will maintain
higher cloud bases/visibilities across central and southeastern tafs late this evening.
Further north...a drier northwest flow behind the front is already
resulting in improving conds at kbfd at 03z.
Improving conds expected late tonight...as cold front passes south
of PA and drier air works into the area on northwest flow. Model soundings
support mainly VFR conds by 09z with the exception of jst...where
residual low level moisture ascending the high terrain should result
in lingering MVFR stratocu. By late morning...any lingering
stratocu around kjst should dissipate...as high pressure builds into
Monday...low ceilings poss northwest mountains Monday night.
Tuesday...am low ceilings poss West Mountains
Wednesday...restrictions likely in rain or snow.
near term...devoir/la corte/steinbugl
long term...la corte/rxr