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Latest PA Weather Story:


000
AWUS81 KCTP 261527
RWSCTP

Regional Weather Summary
National Weather Service State College PA
1125 AM EDT Mon Sep 26 2016

As of mid day, clouds cover the central mountains and the
Susquehanna valley, with sunny skies over the east and west of the
mountains. A thunderstorm ahead of the front is moving along I
ninety near Lake Erie.

Showers and clouds will move into western Pennsylvania early this
afternoon and will spread east into the Alleghenies by late
afternoon. Far eastern Pennsylvania will see mainly sunny mild
weather this afternoon. High temperatures will generally be between
65 over the high ground and 75 over the sunny east. West of the
mountains,the temperature may get close to 80 before the front moves
in. Lows tonight will cool into the upper 40s in the northwest to
around 60 over the southeast.

Winds will get gusty with the front, over the west this afternoon,
the central this evening, and the east over night.

Tuesday will be a beautiful day with an active breeze and lots of
sun. Temperatures should range from the 60s over the high ground to
the 70s over the eastern valleys

$$

Head

Latest Forecaster's Discussion:


000
FXUS61 KCTP 261455
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
1055 AM EDT Mon Sep 26 2016

.SYNOPSIS...
A cold front will move through quickly later this afternoon and
early tonight. After a dry day or two, the forecast becomes rather
wet with a cut off upper low .

&&

.NEAR TERM /THROUGH TONIGHT/...
Considerably amount of clouds stuck in the ridge-valley system of
central Pennsylvania this morning. Sunny to the west and sunny to
the east and here I am, stuck in the clouds with you. A nice early
season cold air damming (CAD) event. For the enthusiasts out
there, the 1000 and 925 theta-e contour show this quite nicely
this AM as does the HRRR/RAP dew point fields. All our clouds are
in the gradient between the warmer air to our southwest and the
cooler drier air to our northeast.

I used the HRRR to texturize the clouds a bit and to better time
the frontal rain headed our way. The coarse GFS/GEFS have too
much light rain too fast. The real front and frontal clouds are
well back in Ohio. Most of the eastern half of central PA should
remain a rain free zone until later this evening.

Showers will arrive in the west later this afternoon and the HRRR
implies some enhanced echoes suggesting some modestly organized
thunderstorms along the line of showers. But the weaken in central
PA due to the CAD event. Pretty stable to the north and east.

The HRRR has chance showers with a narrow cold frontal rainband by
18Z and central PA around 21Z reaching Harrisburg an hour to two
either side of 00Z. The HRRR simulates what looks like a narrow
cold frontal rainband which I timed above. The HRRR also shows
the weak evolution of a wideband back in the cold air later this
evening in central PA. This implies two shots of enhanced
rainfall. The wide cold frontal band does not clear
Harrisburg/York/Lancaster until after midnight as it grows in size
and intensity.

The GEFS too shows similar timing of maximum rainfall periods just
to diffuse. It clears out our light rain by 0600 UTC tonight.

The air behind the front should actual be quite dry and conditions
will improve over night west to east. Precipitable water values
drop about -1sigma below normal overnight behind the front.

&&

.SHORT TERM /TUESDAY/...
All the rain should be gone well before sunrise and our PW values
should be well below normal. Some strong winds to mix down so
should be a breezy day and on the cool side of normal along with
very dry air. Thus it should be a pleasantly cool early autumn
day.

There is not real anticyclone behind this system. But the winds
should diminish as we stabilize in the late afternoon and early
evening.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
Should be relatively quiet weather Tuesday night into Wednesday.
But the cyclone and developing cut-off to our west and the
boundary along the front to our southeast will impact our weather
by Wednesday.

PoPs should creep up in southeast Wednesday due to the frontal
boundary. The deep cut-off low to our west will increase shower
risk in western PA Wednesday afternoon. And by Thursday the big
cut-off will likely bring us very cool and showery weather for a
few days.

Previous: The mid week period will bring the large upper level
low through the Great Lakes and down into the Ohio Valley. The low
will slowly progress eastward with model PWATS increasing through
the latter half of the week. Couple this with the Southwesterly
flow and will allow for an increase of POPS Through the second
half of the week and into the weekend. This will make the forecast
a little milder at night and slightly cooler in the day, but very
nearly normal. Have kept up with the overall trend of increasing
POPs for the latter half of the week and into the weekend. The
upper low is currently progged to lift northeast, but probably not
until then end of the long term period.

&&

.AVIATION /15Z MONDAY THROUGH FRIDAY/...

Mostly VFR about the region. Some low and mid clouds stuck in the
mountains of central Pennsylvania this morning. These clouds may
break up but they will likely linger as broken deck over some
areas. Breaking up is hard to do.

The real front with the potential rainfall is currently racing
across Ohio. We tried to time the onset of the rain and cessation
of the rain based on our mesoscale model, the HRRR. Rain should be
a quick 1-3 hour window in most western areas in the 21 to 03Z
timeframe depending on how far west the airport is.

Rain will take until well after dark to reach KMDT and KLNS and
will be gone well before sunrise.

As the rain and showers come in MVFR and patchy IFR. There could
be some isolated thunderstorms in the western half the State.

Things clear and dry out fast. IFR/MVFR fog and low clouds will
not hold for very long and MVFR should break out fast everywhere a
few hours either side of 11Z.

Outlook...

Tue...No sig wx expected.

Wed...Showers/cig reductions possible late.

Thu-Fri...Sct showers/cig reductions possible, esp w mountains.

&&

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

&&

$$
SYNOPSIS...Dangelo
NEAR TERM...Grumm
SHORT TERM...Grumm
LONG TERM...Dangelo/Ceru
AVIATION...Grumm