Snow Impacts in the Sierra Nevada and Great Lakes

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Here is the latest Area Forecast Discussion for Central PA

This text statement is the latest forecast reasoning from the NWS in State College, PA

See the links at the bottom of the page for previous issuances/versions of the statement as well as our other text statements.

828
FXUS61 KCTP 251835
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
135 PM EST Mon Nov 25 2024

.SYNOPSIS...
* Periods of rain tonight followed by gusty winds and lingering
showers into Tuesday; Wednesday daytime pre Thanksgiving travel
conditions still look good
* Potential travel disruptions for Thanksgiving Day with rain
and wet snow expected
* Cold pattern with lake effect snow Friday into early December

&&

.NEAR TERM /THROUGH TONIGHT/...
Models in good agreement spreading rain showers into the
western part of the forecast area this evening, as a 30kt
southwesterly low level jet and associated plume of anomalous
pwats work into the state ahead of an upstream trough. Strong
large scale forcing and a decent plume of pre-frontal pwats
supports high POPs late tonight into early Tuesday associated
with the cold front passage. Best chance for thunder will be
across southwest into south central PA where MUCAPE peaks
around a couple hundred J/kg 06-12Z Tue. Most likely rain totals
based on latest HREF/EPS/GEFS QPF range from 0.10-0.50" with
the highest totals likely over the western Alleghenies. Cloud
cover and warm advection ahead of the approaching cold front
should result in a very mild night with fcst lows adjusted
higher to the 40-50F range, or +10-20F above the historical
average for late November.

&&

.SHORT TERM /TUESDAY THROUGH THURSDAY/...
The cold front and any associated rain showers should exit the
eastern edge of the forecast area by midday Tuesday. Large scale
subsidence behind the front should result in blustery
conditions with breaking clouds in the lee of the Alleghenies
into the afternoon. A progged west-southwest boundary layer
flow should keep bulk of developing lake effect rain/snow showers
along and to the north of the PA/NY border.

Pressure rises/isallobaric couplet and CAA behind the front
will result in windy conditions Tuesday with fcst soundings
supporting peak gusts 30-40 mph. Diurnal temps may go neutral to
even falling during the day across the western mtns through
Tuesday afternoon. Surface high pressure building east from the
Ohio Valley should supply fair and seasonable conditions with
diminishing winds Tuesday night. Latest guidance indicates a
west-southwest trajectory will continue to keep lake effect
showers north of the border.

Tranquil weather and light winds remain likely for Wednesday
with increasing clouds as surface high pressure slides just
south of PA. However, models are trending faster with the next
system and WAA precip could reach the area earlier than
forecast given strong WAA.

There appears to be consensus emerging with the Thanksgiving Day
storm system with the 25/12Z ECMWF shifting farther to the south
with the sfc low track. While there is still uncertainty to be
resolved, the highest probability for accumulating wet snow
(1-3/2-4") continues to be maximized over the northern portion
of the forecast area (along and to the north of I-80) based on a
blend of WPC/NBM/WWD thermal profiles and QPF/snow amounts.

&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
Late week storm system trending faster with medium range models
indicating greatest probabilities for precipitation on
Thanksgiving day, with POPs trending sharply down after 00z Fri.
Still, much uncertainty exists in overall solution, with GFS
runs continuing to depict a flatter progressive wave and the
ECMWF trending towards a more amplified system tracking farther
north with more robust precipitation along with warm sector
covering more of central Pennsylvania. Sticking with middle
ground NBM for now which is consistent with previous given the
spread to start this extended period. Weekend period into early
next week is far more certain with relatively high confidence
in blustery and seasonably cold weather conditions behind the
late week system, with NW flow lake effect regime over the NW
Mtns very likely Friday into the weekend. Model consensus strong
for an Alberta Clipper to affect central Sat night into Sunday,
which would bring an additional punch of cold air and potentially
more widespread light snowfall depending on the exact track of
the sfc low. Either way, the first several days of December are
looking chilly and changeable.

&&

.AVIATION /18Z MONDAY THROUGH SATURDAY/...
VFR flying expected through the evening. Rain and restrictions
move into the area ahead of a cold front starting at BFD/JST
00-06Z and spread to the east 06-12Z. IFR cigs most likely at
BFD/JST; brief moderate rain could drop visby 1-3SM. Can`t rule
out some ltg in the southern portion of the airspace 06-12Z.
Added LLWS tied to the cold FROPA.

Peak wind gusts of 30-40 mph are expected behind the front into
Tuesday. This gusty WNW flow regime will sustain MVFR restrictions
and rain/snow showers in upslope locations of BFD/JST into
Tuesday afternoon with generally low VFR cigs expected
elsewhere.

Outlook...

Wed...Not as windy with pcpn ending and MVFR to VFR cigs; rain
and snow could reach the airspace as early as Wednesday night.

Thu...High likelihood of widespread IFR/MVFR in rain (south) and
snow (north).

Fri-Sat...Becoming windy. Prolonged MVFR/IFR conditions with snow
showers across the north and west.

&&

.CTP WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$

SYNOPSIS...Steinbugl
NEAR TERM...Steinbugl
SHORT TERM...Fitzgerald/Steinbugl/Banghoff
LONG TERM...DeVoir/Fitzgerald
AVIATION...Steinbugl

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