525
FXUS61 KCTP 010942
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
542 AM EDT Sat Jun 1 2024

.SYNOPSIS...
A ridge of high pressure at the surface and aloft will crest
over the region today bringing another day of abundant sunshine,
warm temperatures, low humidity and light wind.

Clouds will gradually increase and thicken up Sunday with
showers spreading in from the west during the afternoon and
early evening.

It will turn warmer and more humid for Monday and Tuesday with
the midweek period containing the next chance for showers and
possible thunderstorms.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Clear skies, nearly calm air and low PWAT air created
anomalously low temperatures for the second night in a row with
daybreak mins settling into the low and mid 30s across the
perennial cold spots in Elk, Mckean and Potter counties along
with some isolated locations across Sullivan County.
A Frost Advisory is in effect across NW PA until 11Z today.

Elsewhere temps ranged from the upper 30s and mid 40s across
much of Central and Northern PA, to near 50F in the larger metro
areas in the SE.

Air/water spreads exceeding 25 degrees should also support fog,
mainly in the deep river/stream valleys north of I-80 late
tonight.

A sharp upper level ridge will slide over CPA today ensuring
pleasant warm weather with a thin veil of high clouds adding
some detail to the initially blue and cloud-free sky this
morning. The associated surface high will drift slowly east to
the Susq Valley by late this afternoon helping to maintain light
and variable winds over the bulk of the region. A few minimal
gusts up to 10 to 12 kts are possible late this morning through
the mid afternoon.

GEFS 850 mb temps warming into the 12-14 deg C range this
afternoon will support highs ranging from the mid 70s over the
N Mtns, to the low 80s in the Susq Valley.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SUNDAY/...
A shield of cirrus clouds will continue to increase/thicken-up
tonight ahead of shortwave trough and associated sfc low
tracking eastward from the Ohio Valley.

Latest HREF indicates a weak sfc low moving into eastern Ohio
late Sunday with an ill-defined warm front extending into
southern PA.

This will result in lowering/thickening cloud bases and a
several to 8 hour period Sunday afternoon into Sunday night when
showers will become fairly numerous acrs primarily Western and
Southern PA with lower POPS of 40-50 percent across Northern PA.

Cloud cover and an associated lack of instability in the models
indicates thunderstorms are unlikely.

EFS max temps for Sunday are mainly in the 70s. However, later
shifts may have to dial back the temps IF the onset time of the
rain is sooner.

Previous...

Latest 2m temp ensemble plumes are widely diverging, with most
members cooler than the current forecast. Ensemble mean qpf
suggests most likely rainfall Sunday PM of <0.20 inches.

&&

.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
Passage of the shortwave should result in drier weather Monday.
However, the combination of a lingering frontal boundary south
of PA and high pressure to the north could result in persistent low
clouds, especially over Southern PA.

Medium range guidance points to fair and warm weather Tuesday,
with ridging at the surface and aloft over PA. Falling heights
and surging pwats ahead of a deepening upper level trough over
the Grt Lks will result in showery weather Wednesday and
Thursday. At the surface, the latest GEFS and EC both indicate
an occluded front will traverse Central PA Thu PM, as a triple
point low passes south of the area. This scenario favors
relatively stable air over the forecast area with a limited risk
of severe weather. Ensemble plumes suggest most likely areal
average rainfall Wed-Thu between 0.5 and 1 inch.

Latest GEFS and EPS indicate drier weather Friday, as the low
level jet/plume of highest pwats shift east of PA with the
exiting cold/occluded front. However, scattered, diurnally-
driven showers appear possible, especially over the NW Mtns,
associated with the deep upper trough/closed low parked over
the Grt Lks.

&&

.AVIATION /09Z SATURDAY THROUGH WEDNESDAY/...
High pressure over the region today will keep light winds and
clear skies across the area into this evening. The airmass is
too dry to see fog early today.

Clouds will be on the increase by early Sunday morning across
the far west, and later in the morning across eastern areas.

Conditions will lower by 12Z Sunday across the far west, and
later in the day across the Susquehanna Valley.

Outlook...

Sun...PM Sct showers and thunderstorms

Mon...Patchy AM fog, slight chance of PM t-storms.

Tue-Wed...Showers and thunderstorms possible.

&&

.CLIMATE...
With only 1 day left, the preliminary monthly summary for May
2024 would be notably warmer than the historical average
(ranking in the top 5-25th warmest) with near to above normal
precipitation. CLMs should be issued overnight on the midshift.

&&

.CTP WATCHES/WARNINGS/ADVISORIES...
Frost Advisory until 7 AM EDT this morning for PAZ005-006-010-
011.

&&

$$

SYNOPSIS...Lambert
NEAR TERM...Lambert
SHORT TERM...Lambert
LONG TERM...Fitzgerald
AVIATION...Martin
CLIMATE...Steinbugl