Area Forecast Discussion
Issued by NWS State College, PA

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FXUS61 KCTP 131952
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
252 PM EST Tue Feb 13 2018

.SYNOPSIS...
The area of high pressure that brought residents of Central
Pennsylvania and the Susquehanna Valley abundant sunshine, light
wind, and near normal temperatures today will drift east and
off the New England coast tonight. An increasingly moist
southeast to southerly flow will develop later tonight and
Wednesday bringing overcast skies and patchy light rain, or even
some light freezing across the higher terrain through early
Wednesday. The second half of this week will be unsettled as a
strong cold front is likely to push southeast across
Pennsylvania by early Friday bringing the likelihood for rain
showers then much colder temperatures headed into this weekend.

&&

.NEAR TERM /THROUGH TONIGHT/...
High pressure centered near Albany New York this afternoon will
maintain mostly sunny skies for the rest of today across most of
the Central and Northern PA with just variable amounts of
cirrus in most places.

Current 19Z temps are near forecast maxes in mid to upper 30s
over most of the CWA. A few readings around 40F may occur
throughout the larger metro areas of southeastern PA over the
next hour or two.

Thickening altocu and high-based stratocu clouds will steadily
drift to the northeast from West VA and VA late this afternoon
and evening, and will overspread the SW half of the state by 01Z
Wednesday and across communities along the West and North
Branch of the Susquehanna by 04Z Wed.

The relatively shallow and warm nature of the clouds, combined
with the lack of significant deep layer/jet forcing will lead to
nothing more than some patchy light rain, light freezing rain or
freezing drizzle overnight into Wednesday. The primary threat
areas for any measurable (and freezing) precip - up to a few
hundredths of an inch would be on the ridge tops and SE facing
slopes in Central and Western PA.

Covered the low threat and spotty nature of any light FZRA/FZDZ
in the Hazardous Weather Outlook for now. Later shifts can
better utilize local Dual Pol radars and high res model data to
better pin down the chance and timing of any freezing precip.

Min temps overnight will be in the 25-30F range, so any light
precip that does fall will freeze on contact with colder and
untreated surfaces.

Winds will be mainly east to southeast at 5-10 kts through dusk.

&&

.SHORT TERM /WEDNESDAY/...
Better chances for rain arrive late in the day or early evening
Wed with upper level diffluence increasing and mid-lvl winds
into the 50s out of the West.

Max temps Wednesday will be about 10F warmer than Tuesday and it
will be mild enough for plain rain everywhere by then.

Rainfall amounts will stay rather light and generally several
hundredths to around 0.10 of an inch, as the forcing continues
to look disorganized.

Temps will be very mild with well above normal mins and maxes
Wed night and Thursday. So, despite the cloudiness on Thursday,
the temps should rise into the 50s and some 60s across the
south. 70F might not be all that far south of the Mason-Dixon
line.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
The extended forecast is anchored by a huge subtropical ridge
that will take up residence off the southeast US coast.

Milder air will work in courtesy of a broad SW flow in the low
levels leading to the precip type likely favoring rain. The
system will have limited access to Gulf moisture so we will not
be looking at a significant precipitation event. A cold front
will push through on Friday and could turn precip over the snow
across the area as it passes. But, much drier air follows for
Fri night and Sat. Normal temps on Sat will be followed by yet
another warm spell kicking in on Sunday.

&&

.AVIATION /19Z TUESDAY THROUGH SUNDAY/...
Varying amounts of Cirrus clouds and widespread VFR expected
for much of the rest of today.

Increasing potential for MVFR conditions across the southwest
half of our forecast area beginning between 13/21-14/00Z at
KJST, then advancing gradually NE after 00Z...reaching KIPT by
around 14/02Z.

There is a low probability for some patchy little mixed
precipitation (mainly light freezing rain or freezing drizzle)
late. For now...left this out of the TAF fcsts... given how dry
the low levels are and anticipated spottiness with little
organized upper dynamics to generate appreciable swaths of
precipitation.

Outlook...

Wed-Thu...Low cigs/light rain possible, mainly N Mtns (KBFD).

Fri...Windy and turning much colder. AM rain, changing to
periods of light snow or snow showers mainly across the Western
Mtns. Cig reductions likely early, and continuing during the
afternoon across the NW mtns and Laurel Highlands.

Sat...No sig wx expected.

Sat night and Sunday...Chance of snow and lowering Cigs/Vsbys
to MVFR with areas of IFR.

&&

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

&&

$$
SYNOPSIS...Lambert
NEAR TERM...Lambert
SHORT TERM...Lambert
LONG TERM...La Corte/Gartner
AVIATION...Lambert



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