Area Forecast Discussion
Issued by NWS State College, PA-- Remove Highlighting --
-- Discussion containing changed information from previous version are highlighted. --
FXUS61 KCTP 020245
Area Forecast Discussion
National Weather Service State College PA
945 PM EST Thu Dec 1 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 over the local area. High pressure will build in
for a brief time Sunday before the next frontal system approached
early next week.
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
-- Changed Discussion --No big changes late this evening as lake effect regime continues
tonight. Lake clouds and flurries hugging areas along and north of
the PA/NY border this evening are showing a slight southward
drift. Latest HRRR in good agreement with this trend for the
overnight...as backing flow upstream flow evidence in northeast
Ohio should bring this to fruition. Expect an increase in snow
shower activity after midnight across the north. Boundary layer
and sfc marginally cold and bands not expected to become very
organized. However...a light accumulation will be seen over my
northern tier overnight. Some sprinkles still mixed in in areas
where lighter precip rates occur.
Mins will be fairly uniform throughout...ranging from the lower
30s northwest to the lower to middle 30s elsewhere.
-- End Changed Discussion --
.SHORT TERM /6 AM FRIDAY MORNING THROUGH 6 PM FRIDAY/...
The cold NW flow will remain air in place for Friday, but again
the cold air is unimpressive so NW snow shower activity is not
expected to amount to more than nuisance amounts. With high temps
expected to be above freezing, most areas will ave a hard time
making any snow stick at all.
.LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/...
As low continues to move further east into the Canadian Maritimes,
lake effect snow showers over the NW mtns will gradually wind down
on Sat. But one last shortwave Fri night could be enough to extend
snow bands into parts of the central mtns for a time.
Sunday brings a brief respite as high pressure moves over the
state. By late Sunday into the overnight, a period of light snow
is possible 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.
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 /03Z FRIDAY THROUGH TUESDAY/...
Widespread MVFR CIGs will persist tonight over the favorable cold
advection/upslope region from KBFD to KJST and possibly extending
briefly at times into the KUNV/KAOO areas, with VFR, BKN-OVC
conds across the east scattering out across the Lower Susquehanna
Valley airfields - KMDT, KLNS, KMUI and KTHV.
An initial mean WSW wind flow in the boundary layer should keep
lake effect snow showers mainly north of the PA/NY border through
much of the rest of this evening.
Latest high resolution model data suggests a slight (10-15
degrees) veering to the mean wind (to about 280-285 deg) in the
rather deep boundary layer (up to 6-7 kft agl) should cause the
bands of enhanced lake effect snow showers to move from from the
Western Southern Tier counties of NY, into NW Pa tonight -
beginning around or shortly before 05Z. Thus, IFR vis reductions
appear likely and more persistent at KBFD later tonight into
Fri-Sat...MVFR CIGS and ocnl SHSN accompanied by IFR vsbys at KBFD/KJST.
Mainly MVFR to low-end VFR cigs and VFR vsbys at KAOO, KUNV and
KIPT. Sct-Bkn VFR Cigs and VFR vsbys expected to continue at KMDT
Sun...Slight chance of light snow/reduced vis at night.
Mon...No sig wx expected.
SHORT TERM...La Corte/Gartner
LONG TERM...La Corte/RXR