Scientific Forecaster Discussion
Area forecast discussion
National Weather Service State College PA
620 PM EDT Tuesday Jul 28 2015
summertime heat and humidity will be the main weather story in
central Pennsylvania into Thursday. A well-defined cold front
will move across the Appalachians and Middle-Atlantic States on
Thursday. Seasonably warm and mainly dry weather will close out
July 2015 and continue into the first weekend in August.
Near term /until 6 am Wednesday morning/...
diurnal cumulus fading fast as evening arrives. Sky cover overnight
should be none with good radiational cooling and eventual valley
fog - mainly in the north. The dewpoints may be low enough to
preclude the widespread fog across the south like we saw Tuesday
Short term /6 am Wednesday morning through 6 PM Wednesday/...
high pressure will be directly overhead but dewpoints do not dry
out all that much from Tuesday. Temperatures will be the story for Wednesday...as
maxes will likely exceed 90f in the valleys of the east and far
south. However...the elevations and more-shallow mixing there
should keep the maxes barely below 90f over the rest of the area.
The highest elevs in The Laurels are the place to go in PA to best
avoid the heat. With the dewpoints holding in the 60s and u50s we
should keep from going into heat advisory values.
Long term /Wednesday night through Tuesday/...
a cold front will approach the region Wednesday night before
crossing the commonwealth through the day on Thursday. Storm Prediction Center has
much of central and eastern PA in a marginal severe risk on
Thursday with the frontal passage.
Heading into this weekend...upper-level troughing over eastern
Canada and the northeastern United States will produce
northwesterly flow aloft. The models indicate a weak cold front
may generate a few rain showers/thunderstorms and rain across mainly north/west PA on Saturday.
Otherwise...mainly dry weather with lower humidity is expected
from Fri-sun. Temperatures will remain near to slightly above
climate normals heading into the first week of August.
Aviation /22z Tuesday through Sunday/...
widespread VFR will continue into the overnight before some fog
begins to reduce visibilities. Expect most locations to go
MVFR...with southeastern terminals having a better chance of IFR/LIFR for
a brief time around sunrise.
VFR/sunny for Wednesday under high pressure. Clouds start to
advance/lower/thicken Wednesday night as a cold front approaches from the
west. Showers in advance of the front may nudge into bfd before
sunrise Thursday. Cfropa still on track for a daytime traverse across
the County Warning Area. Thus...shra/tsra may not be around all day in the
west...and morning stability may be too high to allow for thunderstorms and rain
there. Timing of exit of front is late day/early evening. High
pressure returns for 2+ days.
Thursday...cfropa west/very brief reductions due to sh/tsra.
Sat...mainly VFR...PM thunderstorms and rain poss west.