Area Forecast Discussion
Issued by NWS State College, PA

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FXUS61 KCTP 251119
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
719 AM EDT Sun Sep 25 2022

.SYNOPSIS...
The approach and passage of a cold front will lead to showery
weather today, with a thunderstorm also possible. The proximity
of an upper level disturbance early in the coming week will
continue the threat of showers, especially over the northern
tier of the Commonwealth. By mid-week, high pressure should
build over the region, with drier weather and seasonably cool
temperatures.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
A deepening upper level trough will push into the region today,
as an associated surface low tracks across the eastern Grt Lks.
Strong warm advection at the nose of approaching low level jet
will likely be accompanied by a band of elevated convection
early today across primarily northern Pa.

Much of central and southern Pa is then progged to break into
the warm sector. Partial sunshine, surging low level moisture
and falling heights ahead of approaching shortwave should spawn
showers and thunderstorms during the afternoon hours. The
combination of modest instability and strong deep layer shear of
40-50kts could support organized, severe convection in spots
along and south of advancing warm front. As is often the case,
the amount of clearing and resulting instability remains
uncertain. However, if the latest RAP capes are realized, severe
weather is a threat over the southern half of the forecast
area with a few supercells possible. Can`t even rule out an
isolated tornado, given favorable low level shear profiles in
vicinity of advancing warm front. HREF mean qpf ranges from 0.2
to 0.4 inches today, with spot amounts closer to 1 inch possible
under any heavier thunderstorms.

Steepening lapse rates and strong winds aloft will lead to gusty
southwest winds south of the advancing warm front this
afternoon. Bufkit soundings support gusts of 25-30kt across the
Laurel Highlands. Afternoon highs should range from the lower
60s north of the warm front near the NY border, to the low and
mid 70s across the southeast part of the forecast area.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY/...
Showers should taper off this evening over most of the region,
as the trailing cold front sweeps through. However, low level
instability beneath upper trough, combined with the passage of a
pair of shortwaves, should keep showery conditions going tonight
across the northwest corner of the forecast area.

The northeastern U.S. will reside within a moist, cyclonic flow
regime early next week tied to the above mentioned upper low.
Fairly cold air aloft and the occasional passage of shortwave
energy will keep showers and even isolated thunderstorms in the
vicinity, primarily over the northwest corner of the state and
also coincident with daytime heating during the afternoon hours
each day. We`re still looking at a fair temperature gradient
across the region each day, with highs ranging from the mid-
upper 50s over the northern mountains, to the lower 70s in the
Lower Susquehanna Valley.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
On the large-scale, upper troughing extending from eastern
Canada into the northeastern U.S. at the start of this period,
should have a tendency to flatten out/lift northeast over time,
as upper ridging tries to build from the western Atlantic into
the eastern CONUS. Exact details on how this pattern evolves
will have a significant impact on where tropical cyclone Ian
tracks later next week.

As for the daily sensible weather, Wednesday will likely see
lake effect rain showers over northwestern PA with a pocket of
cool air aloft and northwesterly winds over the Great Lakes.
Thursday looks drier as winds aloft turn more out of the north,
but there could still be an isolated shower in the north and
more cloudiness than the rest of the Commonwealth. High pressure
overhead will result in dry weather Friday.

Towards next weekend, things become much more uncertain, with
the ultimate track of Ian yet to be determined. At this early
juncture, it looks like the soonest we could see any rainfall
(tied to the northern edge of Ian`s rainfall shield) would be
later Friday night or Saturday. Stay tuned, as hopefully
forecast confidence increases over time as we head into next
week.

&&

.AVIATION /11Z SUNDAY THROUGH THURSDAY/...
Low topped storms just about to UNV, so added thunder to
AOO and UNV, as these look like they will hold together
for a bit longer.

More information below.

Adjusted TAFS some for line of showers and isolated thunder
heading into JST and BFD. Will continue to adjust the TAFS
as needed. Storms are not real high, and after looking
outside at cloud deck, BINOVC mid deck, think activity
will weaken some as it heads eastward early this morning.

Earlier discussion below.

Other than mainly BFD and JST later today, went with VFR
conditions. The airmass rather dry, hard to see CIGS getting
too low. BFD and JST have a higher chance for lower conditions
at times, but even at these sites, the lower conditions may
be limited.

Looking at some showers moving from west to east later this
morning, tapering off a bit toward late evening. Perhaps a
gusty thunderstorm, left this out for now.

Monday into Tuesday look mainly dry across much of the
area, but some chance of showers across BFD. Perhaps into
JST later on Tuesday, if the cold air can deepen more and
winds can shift more to the northwest. Often the lower
Great Lakes are too warm yet this time of year, and the
pressure field supports more of a west to southwest flow.

Outlook...

Mon-Wed...Scattered lingering showers downwind of Lake Erie
across north/west PA.

Thu...No sig wx.

&&

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

&&

$$
SYNOPSIS...Jurewicz
NEAR TERM...Fitzgerald
SHORT TERM...Jurewicz/Fitzgerald
LONG TERM...Jurewicz/Travis
AVIATION...Martin


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