Area Forecast Discussion
Issued by NWS State College, PA

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FXUS61 KCTP 231909
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
309 PM EDT Mon Apr 23 2018

.SYNOPSIS...
A slow moving area of low pressure will begin to affect the
region overnight, and the weather will remain unsettled for
most of the upcoming workweek.

Behind this system, an upper level trough will set up over the
eastern U.S. bringing the potential for showers and a
continuation of below normal temperatures into next weekend.

&&

.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
SE flow very gradually moistening up the boundary layer this
afternoon as surface high slides off the East Coast. Dewpoints
have climbed into the 30s even with mixing layer up to around
5000ft. Maxes will peak in the upper 60s most locales. There is
some haze being reported at KSEG at 19z - this is from a plume
of smoke from a prescribed burn in Dauphin County.

Rain will likely reach my SWRN zones around or just before
midnight and continue to slowly spread NE into the Central
Mountains through Tuesday morning. Lows fall into the 40s
tonight, with upper 30s along the northern and northeast
counties.

&&

.SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/...
A slow moving upper low will crawl eastward on Tuesday, reaching
the central Appalachians/SRN Ohio Valley by Tuesday evening.
With the upper low weakening, the surface reflection is progged
to be a rather anemic low which will lead to a forecast of high
POPs but generally light QPF. Worded forecast for periods of
mainly light rain overspreading the entire forecast area before
the day is over. Temps will stay cool as the light precip
adiabatically cools the lower levels, so highs will struggle
just into the 50s.

Main area of precip swings across mainly eastern sections Tue
night keeping PoPs high before tapering off from west to east
overnight. Another upper low reinforces showery weather heading
into Wed.

&&

.LONG TERM /WEDNESDAY THROUGH MONDAY/...
The pattern is expected to become complex and unsettled as the
upper low opens up and begins to shear out through the Mid
Atlantic states. A series of waves upstream are made to
reinforce and help develop a large scale trough over the eastern
US as we move through late week and into next weekend.

The details start to diverge as early as Wed when the EC/ECENS
follow the lead shearing shortwave with a potent closed upper
low that is made to move through the area Thursday with showers
for most of the CWA. The GFS/GEFS show a flat upper ridge
traversing the region yielding a dry and mild day. I looked at
the GEFS and leaned closer to the SuperBlend POPs which show a
dry Thursday afternoon.

By Friday, the old differences remain with the EC products
making for a dry mild day, and the GFS families suggesting at
least a small chance of showers.

It all leads to a low confidence forecast as we move into the
extended range. The latest guidance does agree that it will be
cooler over the upcoming weekend as the upper trough slides
east. Good to note the NAEFSBC hustles the weekend trough east
bringing a fast return to rising heights and milder air for next
week.

&&

.AVIATION /19Z MONDAY THROUGH SATURDAY/...
SE flow very gradually moistening up the boundary layer this
afternoon as surface high slides off the East Coast. But VFR
conditions are the rule areawide, except at KSEg which is
reporting some haze from a plume of smoke from a prescribed
burn in Dauphin County.

Conditions begin to deteriorate tonight from the SW as
restrictions begin to slide across the area. Biggest impacts
will be over the Laurel Highlands tonight and the western half
much of Tuesday before working into the east later in the day.
Rain will likely reach SWRN zones around or just before
midnight and continue to slowly spread NE into the Central
Mountains through Tuesday morning.

Bukfit soundings indicate there will be southeasterly gusts of
15-20kts this afternoon in the vicinity of KJST/KAOO, with
slightly lighter winds further north and east. Winds pickup
again on Tue.

Outlook...

Tue...Rain/low cigs becoming likely.

Wed...AM rain/low cigs likely, then improving.

Thu...AM low cigs possible W Mtns.

Fri...PM showers/cig reductions possible, mainly west.

SAT...Showers/cig reductions possible, mainly NW.

&&

.CLIMATE...
As of midnight Sunday night, April 2018 is in the top 10 coldest
on record. While milder conditions are expected this week, it
would take several abnormally warm days to turn the trend
around.

&&

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

&&

$$
SYNOPSIS...RXR
NEAR TERM...RXR
SHORT TERM...RXR
LONG TERM...La Corte
AVIATION...RXR
CLIMATE...



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