Area Forecast Discussion
Issued by NWS State College, PA

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FXUS61 KCTP 250541
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
141 AM EDT Mon Sep 25 2017

.SYNOPSIS...
Unseasonable late-September heat will continue in central PA
through early week. Mostly dry weather will also prevail with
just an isolated shower possible in spots on Wednesday. A
pattern change will bring cooler, fall-like weather back to the
area for second half of the week and into the upcoming weekend.

&&

.NEAR TERM /UNTIL 6 AM THIS MORNING/...
Skies will remain mostly clear overnight, with nothing more than
thin cirrus over mainly southwest portions, and it will remain
mild. Minimum temps will run about +15 degrees above climate
averages. Some morning fog is expected in the valleys.

&&

.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM TUESDAY/...
Areas of fog in the morning will give way to another very warm
and muggy afternoon by late-September standards with max
temperatures in the mid 80s to around 90F (+15-20 degrees above
normal). It will feel even warmer with max HX values between 90
and 95 degrees.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
The blocking high that has been responsible for the recent
extended spell of dry and anomalously warm conditions is
forecast to start breaking down early this week, with shortwave
energy sliding along the US-Canadian border finally chewing
away at the high heights and bringing some cooler air eastward.

In the meantime Maria is still forecast to drift northward into
the offshore waters off of Cape Hatteras on Wednesday. But the
aforementioned northern stream shortwave finally gives it the
incentive to take a hard turn east as the storm passes 35 deg
north.

For our area, it looks like the first chance we will have to
see any rain might be Wednesday with a weakening cold front that
is destined to fall apart in the unfavorable shear on the
northwest side of the sprawling hurricane. Any rainfall amounts
look to be scattered and light, bringing little change to the
dry conditions we`ve had around here for much of September.

A bit more significant trough drops toward us for the end of
the week into next weekend. The ECMWF looks a bit more potent
but otherwise timing looks comparable between longer-range
models. Not seeing much in the way of noteworthy precipitation
again, with scattered light showers possible through this time.

Biggest change will be that temps will drop off from our streak
of well above-normal levels back toward seasonal normals by
Friday.

&&

.AVIATION /06Z MONDAY THROUGH FRIDAY/...
06Z TAFS sent.

Sunday was a dry and warm early fall day. The main feature
that was interesting was it was breezy. VAD winds at around
500 MB when I left this morning were around 50 knots.

Earlier discussion below.

High pressure over the area will ensure VFR conditions and light
wind through Monday over most of the area. The only concern will
be patchy valley fog early Monday morning (mainly between
08Z-13Z). Based on a combination of SREF probability charts,
MOS and conditional climatology, believe a period of IFR/LIFR
reductions are likely at KBFD/KIPT/KLNS, possible at
KUNV/KAOO/KMDT and near zero at KJST.

Tue-Wed...Patchy AM valley fog possible.

Thu-Fri...No sig wx expected.

&&

.CLIMATE...
Record-challenging late-September heat through early week.
Daily high temperature records from 9/24 through 9/26:

Bradford: 82* in 1961, 83 in 2007, 79 in 1998

Williamsport: 90 in 1961, 89 in 1970, 92 in 1900

Harrisburg: 97 in 1970, 93 in 1970, 91 in 1970

Altoona: 91 in 1970, 90 in 1970, 88 in 1998

*86F as of 332 PM

&&

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

&&

$$
SYNOPSIS...Steinbugl
NEAR TERM...DeVoir/Steinbugl
SHORT TERM...Steinbugl
LONG TERM...RXR
AVIATION...Fitzgerald/Martin
CLIMATE...Steinbugl



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