339
FXUS61 KCTP 201720
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
120 PM EDT Sat Jul 20 2024

.SYNOPSIS...
*More humid start to the weekend with a couple of thundershowers
*Trending hotter but rain-free and less humid end to the weekend
*Seasonably warm with daily opportunities for much-needed rain
 next week

&&

.NEAR TERM /THROUGH TONIGHT/...
Expect isolated to scattered convection to remain confined to
the southeast half of CPA or along/southeast of a low level
convergence/dewpoint boundary located from near FIG to IPT.
Some hints of a weak MCV curl in the MRMS radar loop with area
of weakening thundershowers tracking ENE from Huntingdon into
Mifflin/Juniata and Perry Counties.

A couple of showers/t-storm could linger and be slow to
dissipate/shift to the east tonight as indicated by the latest
hires ensemble mean/NBM precip fields.

High pressure building in tonight should bring clearing skies
(from west to east) and light winds to promote fog formation
into early Sunday morning. Min temps range from a comfortable
50-55F in the in the NW mtns to a muggy 65-70F in the LSV.

&&

.SHORT TERM /SUNDAY THROUGH TUESDAY/...
Fair and warm weather with light wind and moderate humidity
is expected Sunday, as surface ridging and associated low-pwat
airmass builds across the state. Ensemble mean 850mb temps near
17C supports max temps ranging from the low 80s over the N
Mtns, to around 90F across the Susq Valley. Latest HREF
indicates a mix of sun and clouds on Sunday afternoon with some
fair weather cumulus and a broken deck of cirrus.

Clouds will continue to thicken up overnight Sunday night as
low temperatures continue their slow upward trend. Lows by
Monday morning will be ~5 degrees above normal for this time of
year, ranging from the upper 50s in the north to low 70s across
the southeast. By daybreak Monday, showers should be on our
doorstep ahead of an approaching warm front.

Medium range guidance all point to a showery period with high
humidity and more clouds than sun for much of next week, as an
advancing warm front stalls out in the vicinity of PA. The 500mb
pattern features upper ridging off of the East Coast and a
persistent trough over the Grt Lks. A deep southwest flow at the
interface of these features will import GOMEX moisture
northward, interacting with the front to promote multiple days
of diurnally enhanced showers/thunderstorms and potentially
beneficial rainfall. The southern tier of central PA could
really use some rain to lessen the impacts of moderate to severe
drought conditions (D1-D2 drought monitor).

Ensemble plumes indicate that plenty of cloud cover and more
numerous showers/tsra should hold daytime temps to near seasonal
norms Monday through the upcoming week. Surging pwats along the
frontal boundary should translate to very warm/muggy nights.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
An upper-level trough axis will remain centered over the Great
Lakes Wed into Thurs, with unsettled weather continuing for
central PA under a continued chc of (mainly aftn/eve)
SHRA/TSRA. Southwesterly flow at the sfc and aloft will keep us
warm and humid as well.

The trough axis should finally swing through by the end of the
week, accompanied by a cold frontal passage, which should bring
a decrease in PoPs Friday into next weekend. Temperatures look
to remain seasonably warm, although humidity should come down
following the passage of the front.

&&

.AVIATION /17Z SATURDAY THROUGH WEDNESDAY/...
At 15z, considerable high and mid-level cloudiness is
overspreading all but far northwestern PA and some cu is
beginning to pop up. There is a patch of SHRA (and even a bit
of thunder) over the southern Alleghenies (SW of KAOO).

Expect scattered showers (and isolated thunder) to continue to
pop up with the heat of the day, primarily along and southeast
of I-99. Outside of any SHRA/TSRA, VFR conds should prevail.

Skies should clear out later this evening into the overnight
hours, and winds will diminish. This could aid in the formation
of some fog, especially in areas that receive rainfall today.
Have not hit the fog hard at any TAF sites yet, but have hints
of it at several locations.

Sunday should feature predominantly VFR conds, once any fog
burns off in the AM.

Outlook...

Mon-Wed...Patchy early morning fog possible. Otherwise,
scattered (mainly aftn/eve) SHRA/TSRA developing with brief
restrictions possible.

&&

.CLIMATE...
The average temperature from July 1 to July 19 at Harrisburg is
81.2F which is the 4th warmest month-to-date on record (81.3F
in 1966, 2012, and 2020).

The average temperature from June 1 to July 19 at Harrisburg is
78.1F which is the warmest summer-to-date on record.

The average temperature from January 1 to July 19 at Harrisburg
is 55.6F which is the warmest year-to-date on record.

&&

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

&&

$$

SYNOPSIS...Steinbugl
NEAR TERM...Steinbugl
SHORT TERM...Steinbugl/Fitzgerald/Banghoff
LONG TERM...Fitzgerald/Evanego
AVIATION...Evanego/NPB
CLIMATE...Steinbugl/Banghoff