Area Forecast Discussion
Issued by NWS State College, PA-- Remove Highlighting --
-- Discussion containing changed information from previous version are highlighted. --
FXUS61 KCTP 030023
Area Forecast Discussion
National Weather Service State College PA
723 PM EST Fri Dec 2 2016
A large and deep storm system will move slowly across northern
New England through Saturday, keeping a prolonged period of cool
northwest flow and a gusty wind over the local area. A ridge of
high pressure will slide east across the commonwealth for Saturday
night and Sunday accompanied by fair dry weather and light wind. A
weak frontal boundary will then cross the region Sunday night and
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
Cold cyclonic flow over the Great Lakes will keep a blanket of
strato-cu clouds over practically all of the CWA overnight.
Chances for lake enhanced snow will increase as the low level flow
becomes more favorable to steer the snow showers into the northern
mountains. The HRRR shows this support for increased banding by
midnight, and even hints that narrow bands of snow showers could
reach into central areas.
A light accum of a coating to one inch should occur across the
Laurel Highlands overnight, while the NW mtns (specifically Warren
and Mckean counties see snowfall totals of 1-2 inches with locally
higher amounts possible north and west of the city of Warren.
Additional light snowfall Saturday morning from LES showers could
bring 18-24 hour totals to 3 or 4 inches throughout the typical
snowbelt of NW Warren County (and perhaps portions of Mckean
County). However, these amounts will be just under LES Advisory
Criteria of 3 inches/12 hours.
Min temps early Saturday will vary from the upper 20s across the
higher terrain of nrn and wrn PA, to the l-m 30s elsewhere.
.SHORT TERM /6 AM SATURDAY MORNING THROUGH 6 PM SATURDAY/...
The stacked low pressure over moves over the Canadian Maritimes.
The mean WNW boundary layer flow off the Great Lakes will be
persistent with multiple narrow bands of mainly lake effect
snow expected to spread a little more inland (developing south
across the Laurel Highlands) and last into Sat Night.
Clouds will be pesky and linger across much of the CWA right
through the day Saturday.
Max temps Saturday will be slightly colder across the north and
west, but slightly warmer than today (Friday) across the
Susquehanna River Valley. Still, these numbers are within a few
degs of normal for the first part of Dec.
.LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/...
Late Sat night and Sunday brings a brief respite as high pressure
builds east across the state. Sunday evening and night, a period
of light snow is looking likely as a northern stream shortwave
races through the region with a burst of warm advection. QPF looks
to be on the order of a tenth of an inch or less, but occurring
overnight many places could see their first coating of snow of the
young season by Mon morning. Snow is more likely in the NW than
Another ridge moves through on Monday as progressive weather
pattern becomes more active. On Tues there is decent agreement in
bringing the SW US upper low up through the Ohio Valley as a
shearing out shortwave and diffuse 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.
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
Behind the trough, looks like a chilly weekend in store with a
potential sharp dropoff in temps.
.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
-- Changed Discussion --Satellite continues to show a pretty solid deck of clouds covering
all of Central Pennsylvania. Ceilings ranging from low MVFR in
the west and north, to VFR in the east. Additionally, radar shows
an area of light snow and rain moving across norther tier of
Central Pennsylvania this evening. This precipitation is falling
as occasional light snow in KBFD, to occasional light rain in
KIPT. This area of precipitation corresponds well to shortwave
depicted on models.
Persistent WNW flow will keep threat of lake precipitation into
the mountains overnight into Saturday. After passage of shortwave,
flow settles down, which may add somewhat to organization of lake
snow bands. HRRR and RAP has the idea of somewhat organized lake
snows developing into the NW after 03z...then continuing into
Saturday as well.
Overall, MVFR to occasional IFR in snow in KBFD, with same thing
possible at KJST. Will wait and see the evolution of exactly where
banding sets up, and adjust TAFs as appropriate.
Downsloping flow east of the mountains should result in better
conditions further east. Mainly VFR expected at
KUNV/KIPT/KMDT/KLNS through the TAF window. Temporary dips to
MVFR cigs overnight at KAOO.
The entire region will continue to see breezy conditions last
through the next 24 hours.
Sat...SHSN with ocnl IFR vsbys at KBFD/KJST, mainly in the
morning. VFR elsewhere.
Sun...Light snow/reduced vis possible at night, mainly NW Mtns.
Mon...No sig wx expected.
Tue...Mixed precip/low CIGs possible across the nrn mtns, with a
mdtly heavy 0.50-1.00 rainfall expected across much of Central and
-- End Changed Discussion --
NEAR TERM...La Corte/Lambert