Area Forecast Discussion
Issued by NWS State College, PA

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FXUS61 KCTP 070001
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
801 PM EDT Mon May 6 2024

.SYNOPSIS...
Isolated to scattered showers and thunderstorms are expected
across south central PA through this evening. After a lull
Tuesday morning and afternoon, scattered showers and a few
storms are likely for Tuesday night into Wednesday. More
widespread showers are expected Thursday night into Friday with
unsettled and cooler conditions lasting into the weekend.

&&

.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
Regional radar loop at 00Z shows scattered convection extending
from the Ohio Valley eastward into Southern PA in advance of a
potent-looking upper level shortwave over Eastern KY. Coverage
of showers and isold tsra should diminish as the sun sets.
However, falling heights and a bit of elevated instability
support the chance of additional showers tonight across Southern
PA.

Meanwhile, a weak cold front is currently located just north of
I-80 and is progged to slide into the southwest portion of the
forecast area by dawn. Breaking clouds and drier air north of
this boundary should allow temperatures to cool to the mid and
upper 40s over the northern tier late tonight. Further south,
more persistent cloud cover and higher humidity will result min
temps between 55-60F over the southern half of the state.

&&

.SHORT TERM /6 AM TUESDAY MORNING THROUGH THURSDAY/...
Upper level ridging over PA should result in a dry and warm
Tuesday over most of the forecast area with highs in the low to
mid 70s. However, instability and low level convergence in the
vicinity of an approaching warm front will likely result in
scattered PM showers/tsra over the southwest part of the
forecast area. Modest capes of less than 500 J/kg signal little
risk of severe weather. High pressure and associated low-pwat
airmass traversing upstate NY should provide the northern tier
counties with mostly sunny skies Tuesday. Elsewhere, model RH
profiles support a mix of sun and cumulus.

Tuesday night should be very warm for early May, as the region
breaks into the warm sector south of a weak surface low tracking
across the Eastern Grt Lks. Falling heights and surging low
level moisture ahead of the parent shortwave should support a
round of showers/tsra across most of the region Tuesday night
accompanying the passage of the low level jet. The latest HREF
supports POPs from 60-90pct, with the highest POPs across the W
Mtns.

Model guidance tracks the weak surface low north of PA
Wednesday, with a weak trailing cold front coming through
during the morning hours. Any morning showers should give way to
increasing sunshine, as drier air works in behind the front.
Model 850mb temps near 15C support highs ranging from the mid
and upper 70s over the N Mtns, to the low and mid 80s in the
valleys of Central/Southern PA.

Unsettled weather will return Thursday as an upstream trough
approaches from the Grt Lks. Latest guidance tracks the associated
surface low south of PA, resulting in a rainy/cool Thursday,
with elevated convection and a marginal risk of severe wx along
the soutern tier counties. Will likely be undercutting NBM temp
guidance Thursday if current model trends hold. Latest ensemble
plumes support rain totals Thursday of around a half inch.

&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
A notable trend toward cooler conditions for late this week
through the coming weekend as a broad trough develops over the
Glakes and Eastern U.S. with several smaller scale shortwaves
moving southeast within the northern branch of the upper jet.

The surface low and deepest moisture is progged to shift east
of the area Thursday night. However, falling heights ahead of
the positive tilt upper trough (and cold 700 mb temps falling to
around -4C) will likely support scattered-numerous, mainly
diurnal showers Friday through Sunday. A low-topped tsra cannot
be ruled out Friday afternoon/early evening.

GEFS mean 850 mb temps slip to between +2 and +4C (or about -1
sigma) Friday night through Saturday, before rebounding a few
deg C Sunday into Monday. Mean 925 mb temps of just 8-10C later
Friday through Sat morning will likely top even cooler LLVL air
under cloudy conditions.

This cool airmass (with Canadian origin and trajectory over
Lake Erie waters still in the upper 40s to around 50F) will
combine with numerous late morning through early evening showers
across at least the Central and Northern part of the CWA Friday
to likely yield the coolest day we`ll see til this Autumn with
high temps staying in the U40s in some spots across the Northern
Mtns. Highs in the mid 50s to mid 60s will be common heading
southeast from the Allegheny Front.

Temps will still be 2-5 deg F below normal over the upcoming
weekend with mins at night near to a few deg F above normal due
to varying amounts of clouds and at least a light breeze, which
should limit any potential for frost to the patchy variety and
confine it to the Northern Mountains Sat, Sun and Mon mornings.

&&

.AVIATION /22Z MONDAY THROUGH SATURDAY/...
Conditions remain mainly VFR for much of the central PA
airspace this Monday evening. Only reductions attm are from
showers with a few lightning strikes possible around KAOO for
the next hour or two. Another area of showers sliding
northeastward from SW PA could clip KJST as well.

Conditions should slip back through MVFR to IFR in central and
tonight through the mid morning Tuesday with areas of LIFR in
fog and low cigs possible for 2-4 hours centered on daybreak
Tuesday across the Middle and Lower Susq Valley.

In contrast, high pressure building into northern PA from the
Grt Lks, will push drier air into that part of the state,
keeping conditions mainly VFR there through tonight.

A warm front lifts northeast across western and central PA
Tuesday afternoon and night, leading to a trend toward
increasing areal coverage of showers and thunderstorms and a
higher frequency of MVFR and brief IFR conditions.

Outlook...

Tue...AM low cigs/showers possible southern tier of PA.
Scattered evening tsra impacts possible W Mtns.

Wed...AM low cigs/tsra possible.

Thu...Periods of rain/low cigs likely. Scattered afternoon
TSRA.

Fri and Sat...Showers with periods of low cigs possible.

&&

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

&&

$$

SYNOPSIS...Bowen
NEAR TERM...Fitzgerald
SHORT TERM...Fitzgerald/Bowen
LONG TERM...Lambert/Fitzgerald/Colbert
AVIATION...Lambert/Gartner