000
FXUS61 KCTP 261939
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
339 PM EDT Tue Oct 26 2021

.SYNOPSIS...
A powerful autumn nor`easter intensifying off the Mid Atlantic
Coast will bring periods of rain, gusty winds, and cooler
temperatures to central PA through tonight.

Additional moderate amounts of rain between 0.50 and 0.75 of an
inch will fall through early tonight across parts of the mid
and upper Susquehanna Valley into the Poconos.

Conditions will dry out for Wednesday and Thursday allowing
temperatures to moderate. Another storm system will bring more
wet weather Friday into the weekend. Scattered showers could
linger into Halloween especially over the Alleghenies. The
outlook to start November leans toward near to below average
temperatures and precipitation.

&&

.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
A large area of light to moderate deformation rain pivoting West
and Southwest across PA within a negative-tilt upper trough with
a closed low center sliding across Central PA late this
afternoon.

MRMS 6 hour QPF - FFG Ratio isn`t imposing at all across our CWA
with our Ncent Mtns peaking out at around 30 percent of guidance
with the most recent late morning/afternoon rainfall. Across the
southern half of PA, rainfall amounts since 12Z have been
generally under one tenth of an inch.

Expect rain of light to ocnly moderate intensity to fall through
the first half of tonight along with NW wind gusts between
30-35 kts across the SW half of the CWA beneath the descending,
left and thermally direct entrance region of a 115 kt upper jet.

Winds and POPS will decrease after midnight tonight as the sfc
and upper low moves SE of Long Island.

Min temps early Wed will vary from near 40F across the highest
terrain of the NW and Laurels and upper 40s to low 50s
elsewhere.

&&

.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/...
High confidence in dry weather Wednesday through the daylight
hours Thursday thanks to high pressure at the surface and aloft
and deep layer warming.

It will remain breezy on Wednesday as the deep coastal storm
wobbles slowly away from the New England coast into the north
Atlantic. MaxTs Wed afternoon will rebound to a few deg F above
normal (or the mid 50s to low 60s West to East across the CWA.

Although the growing season has ended for parts of CPA,
Wednesday night/Thursday morning could be frosty over parts of
the western and central zones with fcst lows in the 35-40F
range.

&&

.LONG TERM /THURSDAY THROUGH TUESDAY/...
Medium range guidance
is in remarkable agreement through the rest of the long term
forecast, lending confidence to a forecast of rain spreading
southwest to northeast Thursday night into Friday morning.
Friday into Saturday, as a slow-moving low pressure system
tracks south of the state. The most significant rain appears
likely to fall Friday with passage of low level jet, then
lingering lighter rain through Saturday associated with low
level easterly flow ahead of surface low. This could have heavy
rainfall associated with the system, with over 1" in ensemble
plumes by Saturday but exact amounts have yet to be ironed out.
Have continued to undercut NBM high temps Friday and Saturday,
due to its warm bias in cold air damming scenarios.

A trend toward drier and brighter conditions appears likely
Sunday into Monday, as upper low lifts out and surface ridge
builds in from the Ohio Valley.

By early to mid next week, models indicate another system and
cold front approaching from the NW. Too early to tell the
strength and timing of this system, but included chance POPs in
NW areas early/mid next week.

&&

.AVIATION /19Z TUESDAY THROUGH SUNDAY/...
As the coastal low takes over, and a compact upper low center
drifts across Central PA late this afternoon and evening,
expect light to moderate rain to continue to pivot west and
southwest across Central PA and the Susq Valley with IFR to MVFR
Cigs and MVFR Vsbys. Areas of LIFR and LLWS expected across the
Western Mtns through tonight.

NW winds gusts will be in the 30 to 35 kts range at numerous
airfields (Esp across the SW and Scent parts of PA beneath the
descending branch of a potent nwrly upper jet core).

Improving conditions to mainly VFR will be on the increase
through this afternoon with gusts into the mid and upper 20s
(developing across the Susq Valley at similar speeds later this
afternoon as the llvl pressure gradient tightens.

Outlook...

Wed...Mainly VFR.

Thu...VFR conditions early, then widespread rain with lower
CIGS and visibilities late.

Fri...Widespread rain with lower CIGS and visibilities.

Sat...Widespread lower CIGS and light rain early, which could
gradually improve with time.

&&

.CLIMATE...
A record high temperature was set in Harrisburg on Monday.
The temperature reached 76 degrees, which broke the old
record of 75 degrees set in 1963.

A warm October so far.

October 2021 will be remembered for its persistent warmth
& lack of cold nights. As we approach the end of the month,
let`s contextualize the record-setting warmth:

RECORD WARMEST LOWEST OCTOBER TEMPERATURES
(The temperature never fell below this value in October)

               CURRENT RECORD      OCT 2021 SO FAR
Harrisburg:      43F (1984)         44F (10/19)
Williamsport:    38F (1971)         39F (10/19)
State College:   38F (2014)         39F (10/24)


RECORD HIGHEST AVERAGE TEMPERATURE
(Average of all the highs and lows in the month of October)

               CURRENT RECORD   OCT 2021 (THRU 10/23)
Harrisburg:     64.4F (2007)    61.6F (RANKS 3RD MONTH-TO-DATE)
Williamsport:   59.4F (2007)    64.4F (RANKS 2ND MONTH-TO-DATE)
State College:  59.2F (2007)    61.5F (RANKS 2ND MONTH-TO-DATE)

RECORD HIGHEST AVERAGE LOW TEMPERATURE
(Average of all the low temperatures in the month of October)

               CURRENT RECORD  OCT 2021 TO DATE (DIFF FROM RECORD)
Harrisburg:     53.6F (1984)        56.3F (+2.7F)
Williamsport:   50.1F (2007)        53.1F (+3.0F)
State College:  49.8F (2007)        53.0F (+3.2F)

&&

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

&&

$$
SYNOPSIS...Lambert/Steinbugl
NEAR TERM...Lambert
SHORT TERM...Lambert/Steinbugl
LONG TERM...Fitzgerald/Wagner
AVIATION...Lambert
CLIMATE...Steinbugl