Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion 
National Weather Service State College PA
542 PM EST Thursday Nov 20 2014

Arctic air will continue to move into the region on a gusty west
wind. High pressure will bring more tranquil conditions Saturday
before an approaching storm system brings a chance of rain showers
Sunday into the first part of Tuesday.


Near term /until 6 am Friday morning/...
all eyes are on lake effect snow edging southward toward the northwest
mountains of PA this evening. Blyr flow will gradually veer to the west-northwest
this evening in the wake of a weak trough passage...pushing the
a dying single band into Warren/McKean counties. Near term models
indicate the heaviest snow will fall across the northwest mountains between
02z-05z from remnants of this single band...then as flow becomes
Cross Lake...expect lighter multiple banded le snow the rest of
the night.

Haven/T changed the configuration of the headlines or the
expected snow amounts significantly since overall thinking has not
changed. Latest blend of higher res model quantitative precipitation forecast...combined with snow/water
ratios near 20 to 1...should produce local amts of around 6 inches
across northwest Warren Colorado...while most of Warren/McKean cos get advisory
type amts. Further south along the alleghenies...expect only scattered
-shsn due to lack of lake moisture with any accums to less than
an inch. Elsewhere...downsloping flow east of the mountains will result
in a dry but cold night.

Overnight lows in the teens to around 20 will be well below
normal. Wind chills will range from around zero over the around 10-15 above over the southeast.


Short term /6 am Friday morning through Friday night/...
Friday will see the lake effect snows gradually wind down as high
pressure builds into the region bringing lowering inversion
heights. Flurries and even the possibility of isolated/narrow
bands of les blowing well inland on an approx 310 degree axis may
affect the Central Ridge and valley region and communities along
the West Branch of the susq river...but this threat will wane as
well as the high approaches.

High temperatures Friday will be very similar...if not a few degrees colder
than today.


Long term /Saturday through Thursday/...
an amplifying upper air pattern will be in progress at the start
of the period with strong ridges building toward the West Coast
and in the western Atlantic and deep troughing carving out over
the central U.S by early next week. Guidance is trending toward
better agreement concerning stream interaction which is expected
to yield a deep low lifting northward through the Tennessee/Ohio valleys into the upper
Great Lakes by early Monday. A surge of abnormally warm/moist air
ahead of this system will support widespread precipitation /mostly likely in
the form of plain rain/ sun-Monday before colder cyclonic flow aloft
behind the trailing cold front brings a drying trend along with
colder temperatures by midweek.


Aviation /00z Friday through Tuesday/...
a gusty west wind of 15-25kt today will diminish somewhat to
10-20kt overnight.

All taf sites remain VFR as of early evening...and should
continue through the evening hours. The possibility persists of
an isolated snow shower or two bringing briefly reduced any widespread snow bands remain north of the
region until later tonight.

Later tonight the pattern will settle into a more familiar one
where most of the region is VFR while the higher western and
northern elevations have the best chance for MVFR with occasional IFR in
scattered snow showers. Bradford stands the highest chance of
significant reductions as lake effect snow bands settle into the
northwestern part of the state overnight into Friday.

Snow showers will gradually wind down as high pressure builds into
the area. Bradford will likely hold onto reduced conditions the
longest as flow off the lake continues to drag moisture and snow
showers into the northwest mountains...but even there improvement
is likely during the afternoon.


Sat...mainly VFR.

Sun...mainly VFR with a chance of rain showers.

Monday...MVFR with rain showers.

Tuesday...MVFR with snow showers over western high terrain. VFR


Ctp watches/warnings/advisories...
lake effect Snow Advisory until 3 PM EST Friday for paz005.
Lake effect snow warning until 3 PM EST Friday for paz004.


$$ corte
near term...Fitzgerald/la corte
short corte
long term...steinbugl corte/gartner

National Weather Service Glossary of Abbreviations