Area Forecast Discussion
Issued by NWS State College, PA

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FXUS61 KCTP 040319
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
1019 PM EST Sat Dec 3 2016

.SYNOPSIS...
High pressure will slide quickly off to the east on Sunday. A
weak frontal boundary will pass through Sunday night. Another
storm system will affect the area during mid-week.

&&

.NEAR TERM /THROUGH SUNDAY/...
Widespread stratocu will persist through overnight as deep
cyclonic flow continues over the region.

Well-aligned flow on an approx 310 deg axis in the low levels will
maintain several narrow bands of light snow/rain showers across
the NW half of the CWA.

Pops in the chc to low likely category will be limited into this
evening across mainly the higher terrain to the north of I-80,
though some very light rain and snow showers will reach about
20-30 miles south at times with QPF of 0.01 or 0.02 possible in a
few locations. a light additional coating of snow is possible at
elevations over 2000 ft MSL, otherwise, sfc temps are too warm and
precip rates generally to light.

Any clearing of the lower/stratocu deck tonight will be topped by
increasing cirrostratus, then altostratus from the SW.

Temps will be cooler tonight without so much wind to keep us
well-mixed. Expect lows in the m-u 20s across the mtns, and
generally lower 30s elsewhere.

&&

.SHORT TERM /SUNDAY NIGHT THROUGH 6 PM SUNDAY/...
Flow relaxes tonight as sfc ridge slides overhead for Sunday
morning. Some decrease in cloud coverage is expected overnight,
but it turns right around during the day on Sunday. High/mid/low
cloud progression will darken things again wherever
breaks/clearing does occur. The E/SE will stand the best chance
for complete clearing. Temps will be cooler tonight without so
much wind to keep us well-mixed.

Biggest challenge in this cycle is what kind/how much precip falls
Sunday night from the passage of a weak front. All the models and
most of the GEFS members crank out 0.05-0.20 inches of QPF for Sun
night as the feature is carried steadily through by mainly zonal
flow. Most of the precip should be snow, but it is not likely to
stick in many places SE of the Allegheny Front. Just the highest
hill tops of the SE may get a dusting. For a few runs, a weakness
exists in the QPF right through Central PA from W-E. This seems to
be a disconnect between the moisture and the left-exit region of a
150kt jetlet which passes right over the state. Temps are marginal
for accums, and QPF is light. Have drawn 1-2 inches across the
nrn tier of counties. It is a nighttime event, and temps in the
nrn tier are much more likely to be sub-freezing all night.

&&

.LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/...
The ridge moving to the east will be followed by a large
cyclone emanating for a large upper level low moving into the
northern Great Lakes region. There is decent agreement in bringing
the upper low up through the Ohio Valley on Tuesday as a shearing
out shortwave and diffuse the surface low. Unless cold air damming
traps enough chilly air in the low levels to make for some
freezing rain, the precip type with this midwest system looks to
be mainly rain. Have raised POPs into the categorical range as it
seems unlikely that we will get missed.

The end of the week brings some model disagreement with the
GFS/GEFS being faster than the ECMWF with the next large upper
trof and frontal system. Either way, precip looks like a good bet
around the Thu/fri period as all solutions eventually bring this
trough through. So predictability is increasing, but timing issues
remain. Best bet for precip at this point is mainly rain over the
SE as decent push of warm air lifts ahead of the system, with a
rain/snow mix further north where warm air will not infiltrate as
much.

Behind the trough, looks like a chilly weekend in store with a
potential sharp dropoff in temps.

&&

.AVIATION /03Z SUNDAY THROUGH THURSDAY/...
Extensive stratus continues to prevail across Central Pennsylvania
tonight. Typical WNW flow regime, with MVFR ceilings across the
Western and Northern Mountains, with VFR ceilings across central
and eastern airfields. Lake effect streamers continue to become
less organized and diffuse. While these will likely only affect
KBFD and vicinity, there is a slight chance of conditions dipping
into IFR category from time to time.

High pressure approaching from the west will cause snow showers
to diminish overnight. Additionally, the high building in will
allow winds to continue to diminish overnight.

Light precipitation moves in Sunday Night. Mainly rain in the
southeast...a rain/snow mix in central areas...and mainly snow in
the north and northwest.

Outlook...

Sun...Morning restrictions in mountains, then VFR.

Sun Night...Mixed rain/snow event with restrictions. Lowest
conditions in the mountains north and west.

Mon...No sig wx expected.

Tue...Mixed precip/low CIGs possible, especially late.

Wed...Lingering low CIGs possible.

Thu...Mixed precip/low CIGs possible.

&&

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

&&

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


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