Area Forecast Discussion
Issued by NWS State College, PA-- Remove Highlighting --
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FXUS61 KCTP 210055
Area Forecast Discussion
National Weather Service State College PA
755 PM EST Fri Jan 20 2017
Relatively mild but cloudy and unsettled conditions will
persist through the weekend before cooler air makes a return
A complex storm system is expected to move off the Mid Atlantic
coast Monday and Tuesday and bring rain and perhaps a return of
wintry weather. Much colder temperatures will arrive at the end
of next week.
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
Steady rain is pretty much over as the main band of rain slides
to the northeast. Some light showers will linger in the nrn
half of the area this evening under the short wave trough as it
finishes moving to the north/east. Warm air will try to work
down into the valleys this evening. Some additional warming is
expected - esp in the east. The temps will not fall much or
even rise overnight. A few breaks in the lower clouds are
working into the SW at 2 pm, but any breaks should be short-
lived. The clouds will hold on and the light/nil wind and rising
dewpoints/llvl moisture will allow for fog and patchy drizzle
overnight. Some of the worst fog may in the SE.
.SHORT TERM /6 AM SATURDAY MORNING THROUGH 6 PM SATURDAY/...
Some fog and drizzle will linger in the morning, and even into
the afternoon on the ridges. Few if any breaks in the clouds are
expected outside the far lower Susq as the lowest 3kft remain
nearly saturated. Maxes are a tough call with lots of cloud
cover, but an 8-12F rise is feasible. Will run with maxes just a
hair under MOS blend. The central counties will probably top out
in the m-u40s, but most other places will. 60F is possible, but
not likely, in the Laurels and Warren Co.
.LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/...
As the upper ridge is forecast to re-establish itself over the
eastern U.S. early in the period, a very complex storm system is
now forecasted to be settling over the Southwestern US by
Saturday evening. This southern stream low should continue to
track through the southern states before turning northeast over
the eastern US Sunday night into early next week. The mid to
long range models continue to trend warmer Sunday night into
Monday. 850mb and 925mb Temperatures continue to be above 0C
though a snow/rain mix remains possible in the higher
elevations. Have rain as the main precipitation type. The
forecast question through this period is QPF amounts. Based on
latest models, blends, ensembles and national guidance, have
increased OPF slightly based on PWATS, the moist southerly
flow. One limiting factor could be probability of snow/rain mix,
so higher QPFs are possible in the southeast. There remains a
fairly large spread in QPF amounts in the plumes so will
probably need to adjust amounts for later runs.
Snow is possible late Monday night into Tuesday as the low
passes through and ushers in colder air. Couple this with any
residual moisture on the back side of the low could allow for a
wet snow through Northern and elevated regions of central PA.
The models build high pressure over eastern Canada and
gradually ooze colder air south into the NERN US post frontal.
Any high pressure over the region will be short lived as a
upper level low will settle over Eastern Canada. That system
is progged to drag a cold front through the mid Atlantic
After our early week storm system, the eastern ridge is made to
make a rapid rebound, even if for just a short time around
midweek. A fast moving shortwave quickly chews the top off the
ridge with cyclonic westerly flow by week`s end. Colder air
looks to advect into the region bringing in more winter like
temperatures late next week.
.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
-- Changed Discussion --IFR/LIFR stratus covers nearly all of central Pa this evening
northeast of a stalled warm front, which runs from western Pa
southward along the spine of the Appalachian Mtns. Model
soundings support continued low CIGs overnight northeast of
this stalled boundary. Exception may be at JST, which is
straddling the warm front and has risen to VFR at 00Z. A very
close call here, as even a slight retrogression westward of
front could lead to a return to IFR at JST overnight.
Little improvement expected east of the Appalachians on
Saturday, as models continue to show persistent low level
moisture trapped beneath inversion to the northeast of stalled
warm front. Best conditions will almost certainly be at JST,
where VFR conditions appear likely west of front. Elsewhere,
some modest improvement appears possible by afternoon, but
IFR/low MVFR CIGs appear likely to persist through the day.
Sun...Low CIGs likely. Rain advances from S-N late.
Mon...Rain/low CIGs likely.
Tue...AM rain/snow and low CIGs possible.
Wed...Reduced CIGs/showers possible NW.
-- End Changed Discussion --
LONG TERM...La Corte/Ceru