547
FXUS61 KCTP 052338
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
738 PM EDT Sat Oct 5 2024

.SYNOPSIS...
* High pressure moving southeast from the Great Lakes region
  will bring clear skies and seasonably cool temperatures
  tonight.
* A strong cold front will be accompanied by a broken line of
  showers and possible strong thunderstorms Sunday afternoon
  across parts of Northern and Western PA.
* A secondary cold front Monday night will usher in an extended
  period of cooler than average temperatures next week with the
  first widespread risk for frost this fall.

&&

.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
A spectacular early Autumn day is underway in Central PA and
the Susquehanna Valley with plenty of sun, excellent visibility,
a light north-northwest breeze, and low humidity. Afternoon
highs in the mid to upper 60s across the Northern and Western
Mtns and 70 to 75F elsewhere will be near to several degrees
above normal for early October. Will continue to undercut NBM
dewpoints based on model soundings, which show very dry air
above a weak inversion. Ideal for any outdoor activities!

Look for a clear, calm and seasonably chilly night tonight with
temps dipping into the low to mid 40s over most of Central and
NW PA and in the upper 40s throughout the larger metro areas in
the SE. A fairly large air/water delta T will yield patchy
valley fog late tonight/early Sunday. The best chance for fog
will be from northeast PA through south central PA underneath
the ridge axis where winds go calm.

&&

.SHORT TERM /6 AM SUNDAY MORNING THROUGH TUESDAY/...
Periods of broken mid level clouds will precede a warm front
moving NE from the Ohio Valley Sunday morning/early afternoon. A
potent cold front and increasing deep layer West-Southwesterly
shear will arrive for the afternoon/evening hours across
NW/Central PA with one or two lines of SHRA/SCT TSRA.

Strong upper level diffluent flow and the approaching nose of a
slightly anomalous upper jet will combine with the
aforementioned cfront, a 1-2 sigma WSW LLJ, and a band of 1-1.2
inch PWAT air to bring a high probability for one or two bkn
lines of showers and isolated-sct TSRA (potentially containing
brief strong wind gusts from a westerly direction).

05/12Z HREF continues to MU CAPE peaking between 750-1000 J/KG
across the NW Mtns during the mid to late afternoon before
gradually decreasing toward dusk Sunday evening as the axis of
best instability shifts SE of the Allegheny Front. SPC
has upgraded Warren and the western half of Elk/McKean county to
a SLGT risk of Severe weather Sunday late afternoon and evening
within the unchanged MRGL risk area that extends to the I-99
corridor. Damaging straight-line winds are the primary threat,
though hail and a brief tornado cannot be ruled out if storms
along/ahead of the cold front can stay discrete. Best timing
right now is 4-6PM in far NW PA, moving southeast to the I-99
corridor before midnight. Storms will weaken with southeastward
extent and there remain some questions as to whether or not
showers will stay together as they move into the Lower
Susquehanna Valley. The progressive nature of storms will
preclude any flood risk, with most locations getting less than a
half inch of rain.

High temps Sunday afternoon will be mainly in the mid 70s or
8-13 deg F above normal. Rain will quickly come to an end
behind the cold front Sunday night and skies quickly clear out
for most of the area as high pressure builds in. Low
temperatures by Monday morning will range from the mid 40s
across the north and west, to the mid 50s in the southeast.

Enhanced northwesterly flow in the wake of the cold front will
usher in a drier airmass, thus keeping Monday mostly dry.
Cyclonic flow and neutral to falling upper level heights could
allow for a shower in the Alleghenies, but trends have been for
drier air to filter in more quickly. High pressure builds into
central PA Monday and holds some influence through much of the
week, but will have to monitor the potential for a couple
reinforcing fronts through midweek as an upper low near southern
Hudson Bay rotates a couple of lobes of energy through the
Great Lakes and toward PA. Questionable as to the degree of
moisture return and associated rain chances with these at this
time.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
The extended period should feature fairly benign weather
lasting from the second half of next week into next weekend. An
upper-level trough over the northeastern United States early in
the week will gradually pull east and be replaced by zonal flow
or weak upper-level ridging for the late week into the weekend.

At the surface, Canadian high pressure will build overhead
during the second half of the week. This should result in a
stretch of relatively cool, dry weather for central PA.
Temperatures may begin to moderate as we head into next
weekend and the sfc high begins to pull to our east.

&&

.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
High pressure overhead will provide VFR conditions tonight
across Central PA. The best chance for fog will be in northeast
PA overnight underneath the center of high pressure. Can`t rule
out fog developing toward daybreak at IPT, but the risk of fog
elsewhere is low at this time (<30% probs from the HREF).

Once any fog lifts in the morning, VFR conditions continue into
the afternoon with high clouds streaming in from the west ahead
of an approaching cold front. Winds will generally be out of
the south at 5 to 10 knots with gusts to 15 knots, but BFD could
see gusts of 20 to 25 knots. Most guidance shows a line of
showers and thunderstorms moving into the northwest around 22Z.
The storms will continue to move eastward into the evening and
timing will have to be adjusted with future TAF issuances. Brief
visibility and ceiling reductions will be possible as the
storms move through. Isolated damaging winds and small hail will
be possible with the stronger storms as well.

Outlook...

Sun PM-Mon...Showers with CFROPA move west-to-east; isolated
strong t-storm possible over the western 1/2 of the airspace.
Very brief reductions.

Tue-Thu...VFR, no sig wx.

&&

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

&&

$$

SYNOPSIS...Guseman/Banghoff
NEAR TERM...Guseman/Banghoff
SHORT TERM...Guseman/Banghoff
LONG TERM...Evanego
AVIATION...Banghoff/Bauco