412
FXUS61 KCTP 120929
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
529 AM EDT Wed Jun 12 2024

.SYNOPSIS...
High pressure will be centered over the Commonwealth today,
supplying abundant sunshine and warmer temperatures, followed by
a further increase in heat and humidity for Thursday and Friday
as the high drifts off the Mid Atlantic Coast.

A cold frontal passage on Friday will spark a round or two of
showers and scattered thunderstorms, some of which could produce
gusty winds, frequent lightning and hail.

A ridge of high pressure will bring an increased risk of
excessive heat early next week with highs in the 80s and 90s and
heat index values possibly exceeding 100F.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
The stubborn deck of stratocumulus that hung around much of the
CWA on Tuesday (and the Northern Mtns earlier in the overnight)
has lifted to our far NE CWA and will be exiting stage right
shortly.

Some areas of 1/2-1SM Valley Fig will occur across Northern PA,
and some of it could even drop the vsby below 1/4SM.

An area of mainly thin cirrus is seen on regional satellite
imagery drifting east across the CWA. This area of high clouds
will exit our eastern zones by about 13Z followed by some
scattered Altocu then the development of some flat, fair weather
cu this afternoon.

As a bubble of 1018 MB high pressure drifts just east of the
CWA this afternoon, the light West to Southwesterly flow will
combine with the sunshine to advect/vertically mix warmer and
quite dry air across the forecast area. Highs will be in the mid
to upper 70s across the higher terrain and low 80s in the Lower
Susq Valley. These readings will be a few deg F either side of
climo

Sfc dewpoints in the mid 40s to low 50s will lead to min RH
values of 30 to 35 percent this afternoon.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY NIGHT/...
After a tranquil and comfortably cool night (with min temps
near 50F in the perennial cold spots across the Northern Mtns
and Laurel Highlands and mid to upper 50s elsewhere), we`ll see
a further warm up for Thursday and likely Friday across much of
the region.

Many locations will see their warmest temps on Thursday, except
for perhaps portions of southeast PA where temps could be a few
degrees warmer on Fri.

Temperatures on Friday will depend on the timing of clouds and
convection associated with an approaching cold front. Over the
past 24 hours, models have generally sped up the arrival time
and southward progression of the aforementioned front, now
bringing a chance of showers and thunderstorms to the northern
Alleghenies as early as Thursday night, and then dropping south
across central PA during the day Fri with more numerous showers
and thunderstorms.

SPC`s new DY3 outlook paints a MRGL risk for SVR TSRA across
much of Central PA, while a SLGT Risk covers a small portion of
our Eastern zones (the Western Poconos, south through the
greater Harrisburg, Lebanon and Lancaster areas).

Despite forecast high temps near 90 across southern zones Thu-
Fri, relatively low levels of humidity (dewpoints 55-65F) will
hold the heat index to just a couple deg above the air temp.
Thus not anticipating heat products at this time. However, the
+15-20 degree swing from temps well below normal early this
week to the warm weather late this week will be noteworthy.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
Next weekend looks dry, as a northerly flow of drier air from
Canada is advected into our area. Plenty of sunshine and fair
weather is expected for Saturday and Sunday with a beautiful
weekend in store. Any slight cool down on Saturday will be
short- lived, with warmer temperatures progged to build back
into the area Sunday into Monday. A few isolated sprinkles could
be possible in the northern tier of PA with weak diurnally
driven updrafts on Monday afternoon.

By Tuesday, the risk for excessive heat will increase as a
large ridge builds over the eastern US. There remains quite a
bit of spread in model guidance, but potential exists for heat
index values topping 100F in southeast PA Tuesday - Thursday
next week. The ECENS is more bullish with the strength and
northern extent of the ridge of high pressure into PA, which
would result in higher temperatures and heat index values. The
GEFS is a bit cooler with a weaker high and potential convection
associated with a shortwave moving along the ridge, but still
indicates the potential for excessive heat.

Based on this anomalous pattern, the Climate Prediction Center
has placed much of eastern PA in a Moderate Risk for Excessive
Heat for the middle of next week (Wednesday - Friday).

&&

.AVIATION /09Z WEDNESDAY THROUGH SUNDAY/...
06z update... Patchy fog has developed early this morning across
the northern tier river valleys of the Commonwealth, as per
satellite imagery and surface observations. Thus, we expect
KBFD to see conditions as low as IFR through about daybreak. We
have a high degree of confidence (90+%) that fog and low clouds
will burn off quickly later this morning, generally by 12-13z.

Otherwise, VFR will prevail, with a very dry air mass traversing
the region over the next 24 hours or so.

Surface winds look light, generally 5 kt or less.

Outlook...

Thu...Predominantly VFR w/ no sig wx expected.

Fri...Restrictions possible in CB/TSRA.

Sat-Sun...Predominantly VFR.

&&

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

&&

$$

SYNOPSIS...Lambert
NEAR TERM...Lambert
SHORT TERM...Lambert/Banghoff/Colbert
LONG TERM...Banghoff/Evanego
AVIATION...Jurewicz/Martin