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000
FXUS61 KCTP 230958
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
558 AM EDT Fri Jun 23 2017

.SYNOPSIS...
A deep southerly flow and tropical moisture will cover
Pennsylvania today ahead of a deepening trough over the Plains
states. Showers and isolated thunderstorms with locally heavy
rain are expected across central Pennsylvania this afternoon
into tonight. A cold front will push east across the region
during the morning or early afternoon hours Saturday, followed
by drier and cooler air with comfortable humidity that will last
through much of next week.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
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Latest regional radar mosaic continues to show two concentrated
areas of moderate to locally heavy shower activity at sunrise.
The first is associated with the standard ring of fire and
extends in an arc well north of PA from upstate NY and northern
portions of the Eastern GLAKS SW to the Upper Midwest and will
not impact the area in the near to short term. The second is
associated with a 40-50kt LLJ riding northeastward through the
central Appalachians early this morning, with the leading edge
of steady showers having pushed into the Laurel Highlands and
South Central Mountains overnight.


This batch of rain is expected to lift northeast across the
forecast area through 15Z, as anomalous 40+ kt southwesterly
low level jet arrives. Western half of PA still expected to see
the heaviest rain amounts from this feature...with 1+ inch
amounts expected over the Laurel Highlands through midday.
The batch of morning stratiform rain with embedded heavier
convective elements should give way to scattered afternoon
convection, as nose of low level jet lifts past the area and
model soundings support a bit of brightening/increasing
instability by the PM hours. High PW will support locally heavy
rainfall from any showers/storms that form this afternoon and
last into this evening, making some locations more prone to
minor flooding as remnant tropical moisture from the prior TS
Cindy track across the area through tonight.

Kept temps close to Superblend/NationalBlend...ranging from the
low 70s over the northwest mountains, where overcast skies are
expected, to the mid 80s over the Lower Susq Valley, where model
RH profiles support partly sunny skies by afternoon.
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&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SATURDAY/...
*Heavy rain and short-term flooding risk Friday-Friday night.

Local heavy rain threat will last into tonight, but confidence
not sufficient for a Watch at this time. Deep tropical moisture
(PW locally 2"+) associated with the remnants of TS Cindy will
combine with the approaching northern stream trough and cold
front to bring a slightly elevated risk of locally heavy
rainfall and potential flooding to portions of central PA.
Factors arguing against a Watch at this time are fairly narrow
window of heavy rainfall and general longer duration of 2"+
rainfall totals...occurring over a 12 hour plus timeframe.

If one area has a greater risk of minor flooding...it would be
the Laurel Highlands where a multi- model blend incorporating
HIRES models/CAMs remains fairly consistent with location of
max QPF. Enhanced terrain lift will also be a factor over a
region that has the lowest ambient short-term FFG in the CWA.

HWO continues to highlight lower end +RA/FF risk at this time -
later shifts should consider a FF watch at shorter ranges with
increasing confidence.

Heavy rain threat winds down late tonight as deepest
subtropical moisture is shunted east of the region after
midnight. Expect lingering moisture/rainfall associated with
the moisture remnants of TS Cindy to exit the area by Saturday
afternoon.

&&

.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
From a large scale perspective, the medium range forecast will
feature a seasonably strong/amplified upper trough settling over
the Northeast U.S into next week. The theme continues to be
above avg confidence in the pattern but low confidence in the
details.

Drier, low PW air arrives behind the cold front later Saturday with
decreasing clouds and lowering humidity providing a nice start
to the weekend. An extended period of comfortable, low-humidity
conditions with temperatures near to below late June climatology
are expected to last through the early part of next week. A few
cool nights early next week with min temps 40-55F.

Precipitation opportunities will be modulated by shortwave
impulses reflecting weak surface fronts/troughs which have low
predictability at this range. Any pcpn would be generally
scattered in nature and on the light side given below normal
moisture levels for late June. The 22/12z GEFS shows PW values
remaining below average through midweek which would tend to
favor mainly dry wx.

Temperatures should stay on the cooler side of climo through
midweek as the upper level trough shifts east of the area.
Differences continue with the trough evolution later in the
week with the GFS initially more amplified before building SE
U.S. ridge. The EC generally maintains a mean trough over the
Northeast CONUS into the second half of next week.

&&

.AVIATION /10Z FRIDAY THROUGH TUESDAY/...
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Mainly VFR conditions were noted across the region early today
(in the form of 3-5SM vsbys across most of the Susq Valley
airfields and MVFR cigs over the southern tier counties of PA
where a large area of light to moderate intensity rainfall was
occurring and drifting gradually to the east).

Pockets of LIFR cigs due to low stratus/fog were occurring INVOF
KIPT and will persist for the next hour or two before a light
south to swrly breeze develops and clouds become dual layered in
the MVFR/VFR range later this morning.

There should be a several-hour lull in the rainfall late this
morning west, and during the early to mid afternoon hours
across the Susq Valley before an extensive plume of deep
moisture and periods of moderate to heavy rain spread northeast
to blanket most of the state late today and tonight...thanks to
the remnants of Tropical Storm Cindy, that is currently
centered over Arkansas.

Widespread MVFR Cigs and Vsbys are forecast for this afternoon
and tonight with mainly IFR over the western Mtns of PA (taf
Sites KJST...north to KBFD). Embedded TSRA are likely within
the larger rain area this afternoon into early tonight.

Rapid improvement will take place from west to east on Saturday
as the front and remnant tropical moisture slide off to the
east. VFR conditions should return for the most part by morning,
but some lingering showers could keep spotty restrictions in
place in some areas - especially from the Susquehanna Valley
east to the Pocono Mountains.

.OUTLOOK...

Sat...Scattered restrictions in AM showers...otherwise VFR.
Sun...Mainly VFR.
Mon-Tue...Mainly VFR, but with a chance of SHRA/TSRA.
Tue...VFR.
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&&

.EQUIPMENT...
KCCX radar will be offline for approximately 4 days starting
Saturday, June 24th for technicians to install the first of 4
major service-life extension upgrades. The work on the radar has
been scheduled to minimize potential impacts to operations and
will be delayed if hazardous weather is forecast.

&&

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

&&

$$
SYNOPSIS...DeVoir
NEAR TERM...DeVoir
SHORT TERM...DeVoir
LONG TERM...Steinbugl
AVIATION...Lambert
EQUIPMENT...Lambert