Area Forecast Discussion
Issued by NWS State College, PA

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FXUS61 KCTP 232237

Area Forecast Discussion
National Weather Service State College PA
637 PM 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.


Showers and isolated thunderstorms slowly diminishing across
southern half of central PA this evening. Cyclonic circulation and
low heights around offshore upper low circulation created rare NE
to SW storm tracks this evening...with one prolific hail producer
in Lancaster/York Counties. Red Lion saw the ground whitened by
4-5 minutes of pea to nickle sized hail. Very weak environmental
winds but southwest propogating cold pools produced local 30+ mph
wind gusts with isolated tree damage...and an already delapidated
structure in Lancaster County was further damaged.

HRRR continues the current trend of the regional radar mosaic in
dissipating showers completely by late evening. Most areas will clear
out overnight. In areas of rain this afternoon..increased chance
of patchy valley fog.


Tuesday looks to be a generally good day. Low probability of
precipitation. Mostly sunny day.


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 scattered
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.


Sct shra/tsra across the southern half of Pa will dissipate with
loss of heating this evening. A brief vis reduction remains
possible thru arnd 01Z across the southern airfields.

Focus for late tonight will shift to the possibility of patchy
fog, mainly where rain fell during the aftn/evening hours. Both
the 15Z SREF and 18Z downscaled NAM indicate this potential of
patchy fog across southern Pa late tonight and early Tue am.

Widespread VFR conds expected Tuesday, as a ridge of high pressure
builds in from the west.

OUTLOOK...Tuesday-Friday 5/24-5/27

Tue-Wed...VFR/No sig wx expected.

Thu-Fri...Chance of mainly P.M. showers/tstms.




NEAR TERM...Grumm/DeVoir
AVIATION...Grumm/Fitzgerald is the U.S. government's official web portal to all federal, state and local government web resources and services.