Scientific Forecaster Discussion
Area forecast discussion
National Weather Service State College PA
909 PM EST Tuesday Feb 9 2016
A deep upper trough will establish itself over the northeastern
US over the next several days bringing the coldest air of the
season along with a prolonged period of snow showers to western
and northern higher elevations...especially in the snowbelt
locations downwind of Lake Erie.
Near term /until 6 am Wednesday morning/...
Snow has continued to shrink in coverage so the bulk of the
headlines from The Laurels eastward have been dropped. Headlines
have been continued for The Laurels where an extended period of
upslope snow can be expected as colder air filters into the
The main change for the near term was to upgrade the watch for
Warren County to a lake effect snow warning...and to erect a lake
effect Snow Advisory for the neighboring McKean with indications
pointing to a long period of favorable over-lake flow. A Lake
Michigan connection is made to develop under highly-favorable
temperature/lake induced instability conditions which should favor
the usual snow belt areas with locally heavy snow showers and
heavier snow squalls.
Farther downstream the air will dry out as it typically does in
the downslope flow...so most other locations will see little more
Low temperatures will fall into the low to middle 20s tonight.
Short term /6 am Wednesday morning through Wednesday night/...
On Wednesday...the lake effect in the northwest should continue...especially
favoring northwestern Warren country as the west-southwest flow favors most of the
banded snows sliding into New York state.
Temperatures will drop off quite quickly late Wednesday as region receives a
glancing blow of -20c 850mb air. Mins may get into the single
digits on the hill tops of the alleghenies and laurels as wind
chills go below zero in a stiff breeze.
Long term /Thursday through Tuesday/...
*impact weather highlights: snow squalls possible with Arctic
front Friday night-early saturday; frigid temperatures/dangerous
wind chills for Valentines weekend.
Polar vortex dives from Hudson Bay southeast across Quebec and
northern New England Thursday-Sunday. The global models and
ensemble means keep a 'milder' trough pattern in place over the
northeast Continental U.S. Into next week.
The first shot of cold air arrives on Thursday with lake effect
and upslope snow showers tapering off Thursday night. Light to
moderate snow accumulations are likely in the favored northwest
snowbelt and higher terrain along the alleghenies/Laurel
The coldest airmass of the 2015-16 winter season remains poised
to arrive this weekend...as a blast of Arctic air delivers a short
duration cold outbreak to central Pennsylvania. Snow squalls are
possible with the Arctic frontal passage Friday night into early
Maximum/min temperature departures of -20 to -25 degrees below climatology
are forecast Saturday and Sunday. Minimum temperatures Saturday night
into early Sunday morning range from around 0f in the lower susq.
Valley to -10f in the northwest alleghenies. The frigid temperatures
combined with dangerous wind chills /-10 to -25 below zero/ will
result in an increased risk for frostbite and hypothermia.
A slow moderation (warming trend) is expected into early next
week...but with a potential overrunning/warm air advection type snow event.
Aviation /02z Wednesday through Sunday/...
IFR/LIFR conditions will remain widespread...especially along and
southeast of I 80. The drier flow is moving in from the
northeast...which will signal an end to most of the snow
showers...outside of the lake and topographic effected regions. Snow
will continue to taper to flurries as the evening
continues...ceilings will remain low through the evening...but as
westerly flow increases a bit overnight ceilings will improve as well
in central and eastern areas. Lower susq will improve to VFR with
central mountains holding on to an MVFR deck. Western higher terrain
will continue to see some snowflakes in the air with upslope flow
keeping mainly IFR ceilings in place. Expect ceilings to improve toward
Wednesday...mainly IFR in snow western airspace. MVFR-VFR ceilings
Thu-Sat...MVFR in -shsn West Mountains VFR elsewhere.
Sun...no sig weather.
lake effect Snow Advisory from 1 am Wednesday to 1 PM EST
Thursday for paz005.
Lake effect snow warning from 1 am Wednesday to 1 PM EST
Thursday for paz004.
Winter Weather Advisory until 7 PM EST Wednesday for paz024-
near term...la corte