Area Forecast Discussion
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FXUS61 KCTP 021653
Area Forecast Discussion
National Weather Service State College PA
1153 AM EST Fri Dec 2 2016
A large and deep storm system will move slowly through Quebec over
the next couple of days keeping a prolonged period of cool
northwest flow and a gusty wind over the local area. High
pressure will build in for a brief time Sunday before the next
frontal system approaches early next week.
.NEAR TERM /UNTIL 7 PM THIS EVENING/...
Shallow and relatively warm strato cu deck will support little in
the way of precip across most of the northern and western mtns of
the state this afternoon and evening as the mean llvl flow will
remain westerly with little tap of significant moisture off the
upper Great Lakes. Significant breaks in the cloud deck will occur
across the Middle and Lower Susq valley at times. The Central
Ridge and Valley Region will be in between with bkn-ovc high-based
strato cu this afternoon and evening with nothing more than a
sprinkle or flurry.
With the temps mainly in the mid 30s this afternoon across the NW
mtns where frequent snow showers will occur, expect to see less
than an inch or snow accumulation, which will be confined to
grassy areas for the rest of the daulight hours. Elsewhere over
Central and Southeastern parts of the Forecast Area, high temps
will be in the low-mid 40s. Some locations to the east of I-83
and south of I-81 could reach 50F during the early to mid
.SHORT TERM /7 PM THIS EVENING THROUGH 6 PM SATURDAY/...
The stacked low pressure over Quebec gradually moves into the
Canadian Maritimes. The mean boundary layer flow off the Great
Lakes will be persistent with lake effect precip expected to
spread a little more inland (developing south across the Laurel
Highlands) and last into Sat Night.
A weak/subtle feature will slide across the lower lakes this
evening/early tonight, and could briefly enhance the snow rates
and push snow bands into the central mountains. Tonight is the
most likely time for any kind of accums to occur. However, only
about half of the area goes below freezing.
The wind does not slacken (and in fact, could increase by 5-10 kts
in the sustained and gust department) thanks to the axis and left
rear, thermally direct descending branch of a strong 150-160 kt
upper jet lifting north from the Central Appalachians.
Clouds will be pesky and lionger across much of the CWA tonight
through Saturday. Therefore, the overnight min temps will not get
more than 6 to 10F colder than daytime temps. Saturday looks like
much of the same. Second verse same as the first. Have inched the
temps up a little higher than guidance in the SE where the
downslope could help them out. Still, these numbers are within a
few degs of normals for the first part of Dec.
.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
Sunday brings a brief respite as high pressure moves over 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 SE.
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 /18Z FRIDAY THROUGH WEDNESDAY/...
Late morning satellite loop continues to show stratocu covering
most of Central Pa associated with slow moving low pressure over
Southern Quebec. Cold air flowing over Lk Erie is producing lake
effect snow showers across Northwest Pa. Will stick with
persistence at KBFD/KJST this morning and forecast predominantly
MVFR conditions. However, still believe ocnl dips to IFR are
likely with passing snow showers at KBFD as the latest GLMP MELD
indicates. Downsloping flow east of the mountains should result in
progressively better conditions further east, with tempo MVFR
possible this morning at KAOO/KUNV and VFR at KIPT/KMDT/KLNS.
Weak diurnal heating/mixing should result in a modest increase in
CIGS by this afternoon, likely resulting in CIGS between 1-2KFT at
KBFD/KJST and VFR elsewhere. However, passing snow showers could still
occasionally drop vsbys below 3SM at KBFD/KJST through evening.
The entire region will continue to see breezy conditions last
through the next 24 hours. Bukfit soundings support winds between
10-20kts across the entire region today and tonight, with
occasional gusts around 25kts (especially late tonight and early
Sat...SHSN with ocnl IFR vsby at KBFD/KJST, mainly in the morning.
Sun...Light snow/reduced vis possible at night, mainly NW Mtns.
Mon...No sig wx expected.
Tue...Mixed precip/low CIGs possible.
LONG TERM...La Corte/RXR