Area Forecast Discussion
Issued by NWS State College, PA-- Remove Highlighting --
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FXUS61 KCTP 240056
Area Forecast Discussion
National Weather Service State College PA
856 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.
.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
-- Changed Discussion --Showers tracking south of mason dixon line at this hour...with the
majority of central PA slated to remain dry overnight. Only
exception will be the far east...still in close enough proximity
to cyclonic flow aloft associated with coastal Mid Atlantic upper
low...which will keep a slgt chc to chc showers going overnight
from Schuylkill County southward to York/Lancaster Counties. The
remainder of central PA will see at least partial clearing. In
areas which saw rain Mon afternoon.. increased chance of patchy
The aforementioned cyclonic circulation and low heights/low
freezing levels (8.5k feet) 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
-- End Changed Discussion --
.SHORT TERM /6 AM TUESDAY MORNING THROUGH 6 PM TUESDAY/...
Tuesday looks to be a generally good day. Low probability of
precipitation. Mostly sunny day.
.LONG TERM /TUESDAY NIGHT THROUGH MONDAY/...
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
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 /01Z TUESDAY THROUGH SATURDAY/...
Regional radar mosaic at 00Z shows the last of the
diurnally-driven showers falling apart over southern Pa. For much
of central Pa, confidence in vfr conds overnight is high. However,
fog is a concern across portions of southern Pa, esp where rain
fell earlier today. The dwpt depression at KMDT is only 6 degrees
at 23Z, and with clearing skies developing toward sunset it`s an
ideal setup for fog. Current hrrr and lamp guidance not indicating
any vis restrictions there this evening and only mvfr
restrictions late tonight, but felt compelled to paint a more
pessimistic picture in the TAF. Current dwpt depressions and SREF
probs suggest KLNS may also experience some fog late tonight.
Elsewhere, the prospects of sig vis reductions appear low
Ridge of high pressure will build in from the west on Tuesday,
bringing a near certainty of widespread VFR conds.
Wed...No sig wx expected.
Thu-Sat...Isold pm tsra impacts possible.