Area Forecast Discussion
Issued by NWS State College, PA

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FXUS61 KCTP 231523
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
1123 AM EDT Sun Apr 23 2017

.SYNOPSIS...
A frontal boundary will remain stalled to the south of the
state into Monday as an elongated east/west ridge of high
pressure drifts across the commonwealth.

An upper level cut off low will form over the Tennessee Valley
and will carry its associated surface low up the East Coast
early in the week.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Abundant Sunshine and a light northeast to easterly wind will
prevail through the afternoon with just an increase in in
cirrus/cirrostratus occurring over the southern half of the
state.

Temps are one track to reach mid to late afternoon highs in the
60s at all locations, except for the highest ridges across the
Laurel Highlands, where the mercury will top out in the mid to
upper 50s.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM MONDAY/...
It will remain dry tonight despite a weak front dropping down
from the north which may touch the northern tier as it stalls
and gets washed out. The upper low will deepen and cut off over
the TN vly/SErn states through the short term period. Good
moisture flow off the Atlantic and up from the GOMEX will lead
to rain over the Mid-Atlantic. It will push slowly north against
the high pressure over ern Canada and the NE US. Expect some
rain to approach the MD border by sunrise Monday. But, it may
not make much more northward progress through the daylight
hours. Will keep the likely POPs along the MD border and taper
to nil before I-80. Maxes Monday will be warmer in the N than
the S, running from m60s N to m50s S. Rainfall does not look
heavy on Monday, as the best moisture/easterly wind anomalies
pointed to the south of the state and the sfc low will still be
down near Myrtle Beach.

&&

.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
The period of Monday Night to Tuesday Night will be dominated
by the flow around a slow moving cut-off low which eventually
will pass to our south and east. This system will bring clouds
and light rain to the parts of our region for several days. The
models are in fair agreement on timing and position of this low.
Bands of precipitation should begin to streak through the
region, mainly the east Tuesday morning. Timing and position of
the low will change whether or not different portions of central
Pennsylvania get precipitation. Have increased POPS for eastern
PA. The gradient will be tight on any precipitation amounts.
Once this system goes by large scale retrogression will put our
region on the western edge of a relatively strong 500 hPa ridge
and it will get warm fast. It should feel like summer by next
Thursday.

 The potential for rain will be higher in southeastern PA and
much lower in northwestern PA. Rainfall will likely be very
light and the best chance for measurable rainfall will be in
southeastern PA. Enjoy the mostly cloudy and relatively cool
weather while it lasts.

As the 500 hPa low fills and the attendant moves to our
northeast the chance of rain should fall off Wednesday into
Wednesday evening. Our 850 hPa temperatures will rise rapidly
Wednesday and it should be noticeably warmer Wednesday relative
to Monday and Tuesday.

Thursday into Saturday the 850 hPa temperatures will be well
above normal, mainly in the 14 to 16C range and we will be on
the western edge of a rather impressive early season subtropical
ridge. The GEFS and GEFSBC show a closed 5880 m ridge along the
VA/NC/SC coast with +2 sigma height anomalies by Fri-Sat.

Thursday through at least Saturday should be very warm and
humid. We should have several days with high temperatures well
into the 80s. Any precipitation after Wednesday will likely be
in a more summer-like atmosphere so have kept thunder in all
forecasts beyond Wednesday.

The ridge will likely continue retrograding. If the NEAFSBC and
GEFSBC are correct we could be looking at our first enduring
period of warm weather from this coming thursday into the
following week.

&&

.AVIATION /15Z SUNDAY THROUGH THURSDAY/...
Nice, VFR flying conditions will prevail through the afternoon
today with just a gradually increase in high clouds across
southern PA. winds will be from the NE to East at 5-9 kts in
many locations, though some gusts into the teens will occur
across the Laurels INVOF KJST.

Some patchy light rain could push back into the southern tier
counties of PA very late tonight into Monday, as a complex
storm system forms across the southeast states and drifts slowly
north up the eastern seaboard.

Some rain could get into central areas on Monday, and perhaps
into northern PA Monday Night.

Potential for a wet day on Tuesday, as a complex low lifts
northeast along the coast.

Improving conditions for Wed.

Showers and thunderstorms spreading eastward, along and
ahead of a cold front on Thursday.

Outlook...

Mon...Patchy rain spreading slowly northward.

Tue...Rain/low CIGs likely.

Wed...Improving conditions.

Thu...A chance of showers and Thunderstorms.

&&

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

&&

$$
SYNOPSIS...Dangelo/Lambert
NEAR TERM...Lambert
SHORT TERM...Dangelo
LONG TERM...Dangelo/Ceru
AVIATION...Lambert/Gartner


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