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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KCTP 220748
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
348 AM EDT Tue May 22 2018

.SYNOPSIS...
Low pressure over the upper midwest will track across the
eastern Great Lakes tonight and Tuesday, pushing an attendant
warm front into Pennsylvania. A trailing cold front will then
sag southeast across the Commonwealth Tuesday night. High
pressure will build southeast into the region for the second
half of the week.

&&

.NEAR TERM /UNTIL 6 AM THIS MORNING/...
Showers increasing over western and especially northwestern PA
early this morning as warm front advances towards central PA
overnight. No changes to going POPs over NW sections as near 100
percent is supported by latest radar mosaic, thanks to robust
forcing at the nose of low level jet pushing through that part
of the state through the predawn hours. Will maintain lower
POPs of around 50 pct across the southeast portion of the
forecast area. Although the warm front should remain west of the
forecast area tonight, models do indicate a fair amount of
elevated instability, mainly across the Allegheny Plateau. Thus,
will include mention of thunder late tonight, especially over
the western counties.

Increasing cloud cover ahead of approaching warm front will help
to hold temperatures up tonight with expected minimums in the
upper 50s and low 60s most places.

&&

.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM WEDNESDAY/...
A southwesterly low level jet and associated plume of anomalous
PWATs will be overrunning the western Pa warm front early in
the day, resulting in a rainy morning across central Pa. Low
level stability forecasts suggest the warm front, which will
begin the day hung up along the west slopes of the Alleghenies,
will work into the central mountains during the afternoon, while
stable air and low level southeast flow remains entrenched
across the eastern portion of the forecast area. Expect rain to
taper off over the region during the afternoon, as weakening low
level jet shifts southeast of the area.

Focus for the afternoon will be on potential of severe weather
developing in warm sector across the western half of the state.
Overcast skies should give way to breaks of sunshine west of
the warm front during the afternoon, leading to moderate
instability per 18Z model guidance. Large scale forcing ahead of
approaching shortwave over the Grt Lks and favorable jet
dynamics beneath right entrance region will enhance the
convective potential. 0-6km shear in the 40-45kt range will
likely support organized bands of convection and possible
supercells across the western counties.

Cloud cover through at least the first half of the day will hold
temperatures down, although humidity will become noticeable as
dewpoints push back into the 60s. Superblend/NBM indicate highs
Tuesday will range from the low to mid 70s over much of the
forecast area, with readings possibly stuck in the 60s east of
the Susquehanna River.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
A trailing cold front will sag south across the region Tuesday
night, accompanied by dwindling convection. Look for high
pressure and dry weather Wednesday through Friday with
seasonable morning lows and warm afternoons. Saturday is
trending drier and will probably be the warmest day of the
holiday weekend with most locations in the 80s. A more
unsettled, humid and a little cooler weather is likely by the
end of the weekend and on Memorial Day. While there will be pops
in the forecast, still uncertain exactly how wet things will
turn out.

&&

.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
-- Changed Discussion --
Scattered to numerous showers with embedded thunderstorms have
spread across much of the airspace since midnight. Flight
categories have been holding VFR for the most part, but
anticipate lowering trend to MVFR through the predawn hours
into mid Tuesday morning.

Latest guidance favors a consolidation of rain areas over the
eastern airspace by mid-late morning. Current thinking is that
a resurgence of isolated to scattered showers and thunderstorms
will develop in the OH vicinity during the afternoon and move
east southeast in advance of a cold front pushing southeast
from the lower Lakes. A few of these storms may be strong to
severe with localized bouts of hail/wind before weakening during
the evening. The great risk area at this time appears to be over
the southwest 1/3 of the airspace.

It appears the AM rain/clouds will maintain stability and limit
thunderstorm potential over the eastern airfields. Therefore,
kept mention of TS out of KIPT/KMDT/KLNS TAFs.

Outlook...

Wed...AM MVFR/IFR cigs wrn 1/3.

Thu-Fri...VFR/No sig wx expected.

Sat...Mainly VFR with scattered showers/thunderstorms.
-- End Changed Discussion --

&&

.CTP WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$
SYNOPSIS...Fitzgerald/La Corte
NEAR TERM...DeVoir/Fitzgerald
SHORT TERM...Fitzgerald/La Corte
LONG TERM...Ross
AVIATION...Steinbugl