445
FXUS61 KCTP 061153
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
753 AM EDT Sun Oct 6 2024

.SYNOPSIS...
* Today will be another warm day for early October.
* A strong cold front will be accompanied by a broken line of
  showers and possible severe thunderstorms late this afternoon
  into the early evening for western and parts of northern PA.
* A secondary cold front Monday night will usher in an extended
  period of cooler than average temperatures, with areas of
  frost possible by mid-week.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Another clear, cool night is in progress across the
Commonwealth, with developing areas of valley fog evident on
nighttime microphysics satellite imagery. We expect the fog to
burn off fairly quickly after sunrise (by 8-9 am).

Through early afternoon, we expect a fair amount of sunshine for
much of central and northwestern PA, which combined with low-
level warm advection, will help push temperatures well into the
70s for most areas.

We still expect a fairly strong surface cold front to be
approaching the Commonwealth from the northwest by late in the
day, pushed along by a progressive northern stream upper trough.
Forced lift from these two features should be enough to form a
band of showers and embedded thunderstorms. Present indications
are that this band of convection will be entering Warren
county, PA by 5-6 pm.

A sufficiency of instability (500-1000 j/kg), in the presence of
strong vertical shear (effective shear of 30-50 kt), should
support the threat of locally strong-severe late day and early
evening storms across northwestern PA. Presumed increasingly
linear storm modes with time favors damaging straight-line winds
as the primary storm threat.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY/...
We do expect sufficient frontal forcing for a band of showers
and embedded thunderstorms this evening, extending from about
the Endless Mountains, to just east of State College, then down
into the south-central mountains by midnight. After about 7-8
pm, the threat of severe storms should steadily decrease, with
waning instability.

After midnight, showers should further weaken with southeastward
extent, as the best mid-level vorticity advection becomes more
separated from surface frontal convergence.

Lows by daybreak should range from mid-upper 40s over the
northern mountains, to the upper 50s in the Lower Susquehanna
Valley.

From Monday-Wednesday, the large-scale pattern will be dominated
by a deep upper low over Ontario and Quebec, with a cyclonic
W-NW flow across the Commonwealth. This will generally bring dry
and cooler weather for the region, although a few showers from
time-time can`t be ruled out over the northern mountains,
particularly on Monday, when a vorticity lobe rotates through.

The best chance of frost/freeze conditions across northern PA
will be on Tuesday and Wednesday nights, depending on the exact
degrees of night-time clearing and radiational cooling.

We generally expect daytime highs to range from the mid 50s over
the northern mountains, to the upper 60s in the Lower
Susquehanna Valley. Overnight lows look to range from the mid
30s-mid 40s.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/...
The extended period should feature fairly dry weather. An
upper-level low over Quebec and the northeastern United States
will gradually pull east and be replaced by upper-level ridging
for late week into the weekend. Clouds and isolated showers will
be possible across northern PA through midweek given the
proximity of this upper low, but moisture looks limited.
Depending on clearing and how quickly Canadian high pressure
builds overhead during the second half of the week, frost will
be possible. Temperatures may begin to moderate as we head into
next weekend with the surface high beginning to pull to our
east.

&&

.AVIATION /12Z SUNDAY THROUGH THURSDAY/...
12z update... IFR restrictions in lower ceilings and fog at KIPT
is expected to lift and improve to VFR by around 14z. Fairly
high confidence on this (60-80%).

Otherwise, very confident that VFR will prevail much of the day
across the central PA terminals, with S-SW surface winds
increasing by this afternoon and turning locally gusty (up to
around 20 kt).

A band of showers and thunderstorms should impact western and
central PA early this evening. At this point, the most likely
timing at KBFD is 22-00z, then KJST, KAOO, KUNV, and KIPT from
about 00z to 03z. We`re thinking any restrictive conditions
(mostly likely fuel alternate-MVFR) will be brief at any one
site (moderate confidence on this 40-60%).

As the night wears on, a cold front will slice across the state,
with surface winds shifting to NW. Lower clouds should move into
KBFD after 06-08z (70-80% confident), with plenty of uncertainty
on potential fog development just behind any showers (20-40%) at
KUNV, KIPT, and KAOO.

Outlook...

Mon...Potential ceiling restrictions at KBFD and KJST, with
primarily VFR expected elsewhere.

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

&&

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

&&

$$

SYNOPSIS...Jurewicz
NEAR TERM...Jurewicz
SHORT TERM...Jurewicz
LONG TERM...Guseman/Evanego
AVIATION...Jurewicz/Gartner/Bauco