Area Forecast Discussion
Issued by NWS State College, PA-- Remove Highlighting --
-- Discussion containing changed information from previous version are highlighted. --
FXUS61 KCTP 190418
Area Forecast Discussion
National Weather Service State College PA
1218 AM EDT Wed Oct 19 2016
Southwest flow ahead of a cold front will keep much above normal
temperatures over the region right through midweek. Cooler air will
follow the cold frontal passage Wednesday. Unsettled conditions
will redevelop for the end of the week as a series of low pressure
areas ripple up along the trailing cold front. Breezy and colder
weather will move in for the weekend.
.NEAR TERM /THROUGH TODAY/...
A cold front over the eastern Great Lakes this evening will sag
south overnight...with line of showers ahead of the front now
entering northwest PA. Guidance continues to dissipate qpf as
moisture convergence wanes later this evening...so not much in the
way of measurable pcpn is expected south of I-80.
Main impact of the front`s arrival will be to flatten the thermal
ridge...which will lead to slightly cooler overnight mins across
the north and central areas...and several degrees cooler maxes on
Mins tonight will range from the mid 50s northwest to the lower to
middle 60s south...still well above normal.
.SHORT TERM /TONIGHT THROUGH 6 PM THURSDAY/...
Wednesday will still be very mild with almost no additional push
of cooler air behind the diffuse-dying cold front. A blend of
models support the potential for a stray shower over western and
southern areas...with maxes still well above normal for this time
of year. Expect highs to range from the upper 60s north through
the 70s Laurel Highlands through the Central Mountains to the
lower 80s south.
.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
The 18/12Z guidance has come into good agreement on a split-flow
upper trough amplifying over the Eastern U.S. through the end of
the week and into the weekend, with 500mb height anomalies
reaching -2SD by 22/12Z. This will allow low pressure to develop
and track northeast along a stalled frontal zone over the OH
Valley on Thursday and into west-central PA/NY Thursday night
into Friday. Significant backing of mid level heights and upper
trough orientation going negative tilt should slow the system
progression and support broad area of soaking rain along/behind
the front. Favorable right entrance region jet dynamics and above
normal moisture should also aid in producing moderate to locally
heavy rainfall amounts. Followed WPC guidance for the most part
with QPF amounts derived largely from GFS/EC blend. This resulted
in a stripe of 1.5-2.5 inches for 36-hour total ending 00Z Saturday
across the northwest 1/3 of the area.
Low pressure developing northeast of the Turks and Caicos
(currently being monitored by NHC) is forecast to track northwest
and then north ahead of the deep layer trough approaching the East
Coast by the end of the week. The models show some differences
concerning the possible interaction between this low and the
aforementioned surface low with the CMC the most bullish. The full
range of guidance suggests odds are slightly higher for the two
system to remain largely separated with eventual consolidation
and further deepening likely by the time the system reaches
northern New England by early Saturday. This will result in a
colder and brisk/gusty northwest flow pattern with some potential
for wrap-around/deformation precipitation giving way to showery
regime focused downwind of Lake Erie and over the higher terrain
of the Alleghenies/Laurel Highlands. Surface-850mb temps will be
marginally cold enough to support rain/snow showers especially
Saturday night over the NW mtns but no accumulation is expected.
GFS/EC show a fast-moving low diving through the Great Lakes into
early next week. This system has low predictability given it weak
state embedded within a progressive WNW flow aloft.
Temperatures start off very mild for the later half of October
but trend noticeably colder/below normal by the weekend. The
roller-coaster up and down swing in temperatures is not uncommon
for this time of year and will only continue as the calendar
turns towards winter.
.AVIATION /04Z WEDNESDAY THROUGH SUNDAY/...
-- Changed Discussion --Front and associated showers moving into northwest Pennsylvania,
with MVFR conditions at KBFD at 03z. Lowering clouds associated
with the approaching front will continue to progress across
western and central airfields tonight, but with shower activity
expected to dwindle as the front moves into the southeast. This
should limit flying restrictions over the southern and eastern
A larger scale rain event will impact the area late week into the
Tonight...Reductions western and central airfields. Reductions
into IFR or LIFR possible in the mountains, with fog restrictions
Wed...Morning reductions NW half and potentially into central
Thu-Fri...Reductions likely area-wide. Scattered showers SE,
period of rain elsewhere.
Sat...Restrictions NW. Sct showers NW. Breezy.
-- End Changed Discussion --
Daily record maximum temperatures are in jeopardy for 10/18. Here
are the current records:
Harrisburg: 82 in 1908 (new record set 83F at 2pm)
Williamsport: 82 in 1964 (new record set 84F at 3pm)
Altoona: 81 in 1998
Bradford: 75 in 1963
State College:83 in 1938*
*10/18 high will be officially recorded on 10/19 (7am-7am COOP)
report so used 10/19 for record purposes.