Latest Area Forecast Discussion for Central PA

Here is the latest Area Forecast Discussion for Central PA

This text statement is the latest forecast reasoning from the NWS in State College, PA

See the links at the bottom of the page for previous issuances/versions of the statement as well as our other text statements.

000
FXUS61 KCTP 240031
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
831 PM EDT Mon May 23 2022

.SYNOPSIS...
Skies will be generally overcast, but mainly dry conditions
with comfortable humidity will continue across the bulk of
Central and Northern PA into the midweek period.

The cloud cover spreading northeast into the region could become
thick enough to support some light rain showers or areas of
nighttime drizzle across the Southern third of PA tonight
through Tuesday, thanks to a slow moving upper level disturbance
to our south and a persistent, moist low-level southeast flow off
the western Atlantic.

Temperatures will be noticeably cooler and trend below average
through the middle of this week.

Showers and thunderstorms are most likely Thursday and Friday.
A warming trend is forecast during the second half of the week
with more summerlike heat on the horizon by Memorial Day.

&&

.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
830 pm update... Regional radar loops continue to show light
rain trying to make inroads into south-central PA. However, it
is fighting boundary layer dry air and low-level dry advection
from the north. The end result is that actual rainfall at the
surface has not been able to penetrate much farther north than
about US-22/I-78. This evolution has been well anticipated and
we expect this trend to basically continue overnight, with
patchy light rain/drizzle for our far southern counties
(especially the higher terrain of the Laurels) and generally
rain free conditions farther north.

Given overcast skies, we don`t anticipate temperatures to drop
significantly during the night. Lows by daybreak should range
from the mid 40s over the northern mountains, to the mid-upper
50s in the Lower Susquehanna Valley.

Previous discussion... Expansive shield of thickening
altocu/altostratus was spreading northeast across the CWA this
mid afternoon hour. Regional MRMS reflectivity looks rather
ominous with plenty of sub-20 DBZ echoes spreading across the
southern half of PA. However, hi res models and their ensembles
suggest that light rain falling south of the Laurel Highlands
will continue to creep north and erode as it falls into the deep
dry air over the CWA.

Some light rain will make it to around the PA turnpike and
perhaps some sprinkles/late night drizzle as far north as Route
22 before coming to a halt as sfc high pressure to the north and
slightly veering upper flow causes llvl subsidence and
shearing/weakening of the upper level feature to our south.

QPF near the Mason-Dixon line will likely be several hundredths
of an inch or a little more, while the ground should stay from
route 22 north in Central/Swrn PA.

This system is expected to continue moving gradually
northeastward throughout the day, reaching the southern Mid
Atlantic region by early Tuesday morning..

Lows tonight are forecast in the 45-55F range (with some places
across the Lower Susq staying in the upper 50s) and some of the
normally colder locations near the NY border possibly dipping
to near 40F if skies can partially clear late.

&&

.SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/...
The weakening upper trough and sfc wave will linger over the
Carolinas and Delmarva region Tuesday into Wednesday and a
persistent LLVL Serly flow will maintain a fairly thick layer of
stratus with some spotty light showers and/or upslope drizzle
likely over the Laurel Highlands Tuesday into Tuesday night. A
high POP/Low QPF event near the Allegheny front in Scent and SW
PA.

(Tue-Wed) temps will be relatively cool/below normal thanks to
this increasingly moist east-southeast llvl/upslope flow. The
low clouds becoming entrenched to the east of the Alleghenies in
a CAD type fashion Tuesday night through Wednesday.

Given this scenario, the playbook is to be on the cool/warm
side of guidance during the day/night. Rain probs tick slightly
higher into midweek toward 30-40%, but 24hr QPF for day 3 is
essentially 0.00" or a few hundredths at best.

&&

.LONG TERM /WEDNESDAY THROUGH MONDAY/...
An unsettled weather pattern is in store for late week. Model
guidance has a slow-moving cold front move across the region
that will contribute to showers and possibly a thunderstorm, but
there are some timing discrepancies at this point. At this
point, showers seem possible Wednesday through early Saturday,
and then things may dry up for the majority of the weekend.

Prev...
Generally dry weather will continue into Wednesday afternoon,
aside from a possible stray shower in south central PA on
Tuesday or in the Laurels Tuesday night. Medium range guidance
is in relatively good agreement for this week, tracking a slow-
moving surface low west of Pennsylvania. By later Wednesday,
chances for showers and thunderstorms increase as the warm front
pushes through the region, placing central PA back into the
warm sector for Thursday. This will spell widespread
showers/storms for Thursday and possibly into Friday along/ahead
of a cool front. Shower chances may continue into Saturday as
remnant shortwave energy/cyclonic flow may skirt PA from the
upper low across eastern Canada. All signs currently point to
upper ridging returning later Memorial Day weekend, leading to
more summertime temperatures making a return.

&&

.AVIATION /01Z TUESDAY THROUGH SATURDAY/...
Generally VFR conds are expected to continue late this evening
into the early overnight hours, beneath a thickening cloud
deck. Patchy light rain will continue across southern PA as
well.

A low-level easterly flow will develop overnight, with MVFR
cigs developing in the upslope flow late tonight over the
southern Alleghenies (KAOO, KJST, and KUNV). Guidance is a bit
less certain of MVFR cigs developing farther north and east over
the nrn mtns and the Susq Valley. A bit of light rain or drizzle
remains possible overnight across southern PA.

MVFR cigs will persist into Tuesday over the southern
Alleghenies, and the coverage of the low clouds could continue
to expand through the day.

Outlook...

Wed...MVFR cigs could persist due to continued easterly flow.

Thu...Predominantly VFR, with brief restrictions possible in
scattered SHRA/TSRA.

Fri=Sat...Reductions likely in SHRA/TSRA as low pressure
approaches from the Ohio Valley.

&&

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

&&

$$
SYNOPSIS...Lambert
NEAR TERM...Jurewicz/Lambert
SHORT TERM...
LONG TERM...Guseman/Gutierrez
AVIATION...Lambert/Evanego

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