Area Forecast Discussion
Issued by NWS State College, PA

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FXUS61 KCTP 060337
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
1037 PM EST Tue Dec 5 2017

.SYNOPSIS...

A cold front will move east of the area overnight. The weather
will turn noticeably colder as a pattern change brings a
prolonged period of winter chill. The below average temperatures
and mainly dry weather will persist into next week.

&&

.NEAR TERM /THROUGH WEDNESDAY/...

Meso anal shows the cold front is moving quickly, and just moved
east of Williamsport and east of the office here about an hour
ago. Temps have fallen below freezing over my far NW zones, but
radar shows no precip and satellite show skies have cleared, so
the usual scenario of rain changing to snow before ending will
not occur with this cold front.

The cold front will be clearing my SERN zones during the wee
hours of Wednesday. The HRRR suggests the entire CWA is dry by
around 3AM.

Lows will drop into the 20s over the north, and remain above
freezing over the SE. These will still be above normal, but the
trend over the next several days will be downward.

&&

.SHORT TERM /WEDNESDAY NIGHT THROUGH 6 PM WEDNESDAY/...
Only some non-threatening strato cu is possible in the
Alleghenies on Wed. The sky should clear out nicely elsewhere.
The dry air and subsidence will initially make it tough for
post-frontal precip to form. The flow near the lakes will be
more from the WSW, and this would keep any bands which can form
later in the day up to our north. Will leave a tiny POP in the
far NW corner of Warren Co Wed.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/...
Global model and ensemble guidance remains in very good
agreement on the maintenance of high latitude blocking pattern
featuring an amplified ridge-trough configuration over the West
Coast and eastern NOAM. The primary forecast issues will be
embedded shortwaves and associated surface waves/fronts, which
due to their scale and fast mean flow aloft may be difficult to
resolve until the short range time frame. There is high
confidence in a prolonged period of below average temperatures
into mid-December with a reinforcing shot of arctic air possible
next week.

The cold pattern will bring opportunities for snow; lake-effect
is inevitable mid-late week but should remain focused along the
Lake Erie shore into southwest NY given mean west-southwest low
level trajectory. One or more clipper systems are probable and
likely offer the best shot for light snow. Finally, there
appears to be multiple waves of low pressure lifting north along
a western Atlantic front from late week into the early weekend
timeframe, with guidance varying on specifics. There is a
possibility one of these waves could clip the eastern part of
the area with some light snow, but right now the mostly likely
outcome is for precip to stay east of the area or off the coast.

A reinforcing shot of arctic air is looking more likely next
week along with a more favorable northwest flow lake-effect
pattern. The core of the winter cold should grip the area during
the second week of December with some signs of moderation during
week 3.

&&

.AVIATION /04Z WEDNESDAY THROUGH SUNDAY/...
Bands of showers continue to move through the eastern half of
central PA this evening. Expect these showers to keep periods of
IFR at MDT and possible LNS with MVFR likely through 05Z. As the
rain moves eastward the cigs will slowly lift with MVFR likely
overnight. Cold northwesterly flow with gusty winds should
preclude any fog development. Expect skies to clear some this
evening, as dry air works into the area. VFR should dominate the
pattern tomorrow though persistent winds with gusts upwards of
25-30 mph through the daytime are possible.

Outlook...

Wed-Sat...No sig wx expected.

&&

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

&&

$$
SYNOPSIS...La Corte
NEAR TERM...La Corte
SHORT TERM...Steinbugl
LONG TERM...Steinbugl
AVIATION...Ceru/Martin



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