Area Forecast Discussion
Issued by NWS State College, PA-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
FXUS61 KCTP 231143
Area Forecast Discussion
National Weather Service State College PA
743 AM EDT MON MAY 23 2016
The slow moving storm system that brought rainy cool weather all
weekend will slowly edge away from the region today and Tuesday.
A noticeably warmer and more summer-like pattern is forecast from
mid week into the holiday weekend.
.NEAR TERM /THROUGH TONIGHT/...
Classic rule of thumb calls for fog after it rains during the day
and skies clear at night with light winds, and that`s what we are
seeing in many locations tonight. We issued a Dense Fog Advisory
for the next few hours mainly over central and northern areas.
Model agreement is good with respect to the upper low bottoming
out around Cape Hatteras today, with the cyclonic circulation
growing to influence the pattern from New England down to the
Daytime heating and cool temperatures aloft will conspire to
steepen lapse rates and help support scattered showers and
thunderstorms later this morning into the afternoon. Capes are
not expected to be very impressive and shear will be meager so the
anticipation is for pulse thunderstorm development.
HIRES deterministic and ensemble blend favors the southern 1/2-2/3
of the area for the best chance of additional rain through 24/00z
followed by a decreasing/drying trend into the overnight.
Maximum temperatures will rebound into the upper 60s and low 70s
which is near to slightly below normal with the largest departures
on the order of about 5 degrees across southern PA.
The chances for rain will shrink steadily overnight, but with the
edge of the cyclonic circulation associated with the upper low
still slopping over eastern Pa, the chances for a shower never go
to zero over my far eastern zones. Lows will range from the mid
40s north to mid 50s south, which will be near to even a little
above normal in most locations.
.SHORT TERM /TUESDAY/...
Highs Tuesday will rise into the lower 70s over higher elevations
of the west and north, and in the mid to upper 70s elsewhere.
Other than a small chance for a lingering shower east, still on
the outer edge of the amazing late spring upper low, most areas
will be bright and dry as the warming trend really gets under way.
.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
Extended guidance continues the idea the development of an eastern
ridge/western trough pattern, bringing the arrival of the first
extended period of summer-like temperatures and humidity.
By Wednesday... central PA will be under rising
heights as the low lifts out and the ridge bulges east. At the
same time a weakening back door cold front will be sliding out of
Canada into the rising heights aloft. The models use this to
develop showers and thunderstorms Wed afternoon and evening.
Precip confidence is never terribly high with surface fronts
moving into ridges aloft.
By Thursday we will be embedded in a broad wsw flow aloft.
Slightly above normal PWATS support the idea that humidity will
become noticeable over most of the area for the first time this
warm season. It also means we will be susceptible to mainly
afternoon convection pretty much on a daily basis into the
weekend. The limiting factor will be the eventual sharpness of the
upper ridge and how warm we manage to get aloft. The GFS is very
aggressive poking the Bermuda ridge strongly up over the eastern
U.S. Saturday while the ECMWF is a little flatter. The NAEFS is
more in line with the GFS which hints that Saturday could be the
day with smallest convective chances. I don`t have anything more
than chance pops in the extended given the muddy nature of the
ridge and low confidence that it will be able to shield us from
upstream convection that will be embedded in the flow.
The highest confidence part of the forecast is for temperatures to
be above normal through the end of the month.
.AVIATION /12Z MONDAY THROUGH FRIDAY/...
-- Changed Discussion --Some mid and high clouds above the fog...but the fog should
be gone here shortly.
12Z TAFS sent.
Earlier discussion below.
As of 5 am...sites that saw some clearing quickly had dense
Expect the fog to burn off by 12Z...given the mid May sun angle
and that most sites still have light breeze.
Given the cold air aloft...there could be a few showers around
the area...perhaps a rumble of thunder. VCTS in the TAFS.
Skies clear out tonight again.
Tue-Wed...VFR/No sig wx expected.
Thu-Fri...Chance of mainly P.M. showers/tstms.
-- End Changed Discussion --
Dense Fog Advisory until 8 AM EDT this morning for PAZ004>006-
NEAR TERM...La Corte
SHORT TERM...La Corte
LONG TERM...La Corte