569
FXUS61 KCTP 030319
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
1119 PM EDT Thu May 2 2024

.SYNOPSIS...
-Warm/dry weather with lower humidity continues for Friday as
 high pressure slides to the northeast.

-Unsettled starting Friday night with occasional showers and
 thunderstorms. The heaviest rain will be Friday night in the
 west and Saturday in the southeast.

&&

.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
Previous discussion... Dry air covers the entire CWA, now with
Td 33F at BFD and readings nearing 50F in the far SE. The upper
high is right overhead and keeping even the high clouds at bay
for now. There will be some high clouds move in from the west
overnight, but not thick enough to affect the sfc temps. Expect
mins in the m40s at BFD to the m50s in the SE as the wind goes
calm in lots of places.

715 pm update... All remains quiet this evening, with very dry
boundary layer air in place across the Commonwealth. Upstream
satellite imagery and near-term model guidance shows a gradual
influx of higher-level cloudiness later tonight into Friday
morning, but that looks like about it. Some of our guidance is
suggesting that an area of maritime low cloudiness could impinge
on NJ and far eastern PA, but we think this lower cloud mass
will very likely stay east of the Susquehanna Valley overnight
and early Friday.

By daybreak, low temperatures should range from the mid 40s over
the northern mountains, to the mid 50s over south-central PA.

&&

.SHORT TERM /6 AM FRIDAY MORNING THROUGH SUNDAY NIGHT/...
Sfc ridge slides E/NE on Fri, and moist return/srly flow brings
dewpoints back into the u50s W and l50s E. Stability dips over
the western mtns with TSRA popping by mid-aftn in the highest
elevation of the Laurels and in the ANF/far NW. These should
multiply and spread to the east through the night. Some of these
could be moving slowly and PWAT will be 1.25" over the west by
sunset. FFG is 1-1.5"/1hr in the west, and slightly higher
east. Thus, there is a MRGL risk for excessive rainfall over the
western third/half of the CWA due to potential for heavy
rainfall. Have increased PoPs to likelies and low-end catg for
Fri night for the SWrn half of the CWA.

A slow moving frontal system combined with anomalous pwats will
bring periods of rain to central PA this weekend. A few non-
severe thunderstorms are possible, most likely along and west
of the Alleghenies on the edge of warmer air surging into the
upper Ohio Valley. The eastern slopes of the Alleghenies into
the Susquehanna Valley will noticeably cooler with rain, low
clouds and moist southeast flow. We trimmed max temps on
Saturday due to the CAD pattern setup. Rain/showers continue on
Sunday with highs recovering ~10F on the western and southern
periphery of the CWA. Despite the relatively high moisture
available, overall stability should limit rain rates especially
east of the mtns and preclude flooding risk. 48hr blended mean
QPF ranges from 0.50-0.75" with spot amounts up to 1 inch
possible.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
The extended period will trend milder and remain unsettled with
several chances for rain. A cold front will stall near or south
of the MD line Monday and Tuesday before lifting to the
northeast (as a warm front) into midweek. The favors the best
chance for rain the SW zones on Monday before POPs increase to
50-70% Tuesday into Wednesday. After a weekend cooldown, temps
will trend warmer/back above climo into the 70s to low 80s.

With several chances for rain next week along with persistent
mild temperatures, green up should rapidly expand into northern
PA thus ending the spring fire weather season. Additionally,
there is no chance for frost or freeze conditions through the
end of the week.

&&

.AVIATION /03Z FRIDAY THROUGH TUESDAY/...
00z update... VFR/unrestricted conditions should remain in place
across central PA terminal sites into Friday evening. Confidence
on this scenario is fairly high (70-90%).

Two potential flies in the ointment. First, an area of lower
cloudiness backing in from the Atlantic across NJ and perhaps
southeastern PA later tonight and early Friday. There is low
(10-15%), but non-zero chance that these clouds reach KLNS for a
brief time. If they did, fuel alternate or even IFR ceiling
bases would be possible. Secondarily, an area of showers could
reach the Allegheny Highlands late in the day Friday (as early
as 21-22z) and perhaps bring fuel alternate-MVFR restrictions at
KJST and KBFD. Once again, the threat is relatively low
(10-20%), but certainly non-zero.

Light surface winds overnight (5 kt or less), will increase out
of the SE to 5-10 kt Friday. Occasional gusts of around 20 kt
could occur in the afternoon at KJST.

Outlook...

Sat PM-Sun...Widespread restrictions across the central and
western mountains due to low cigs. SHRA likely with a chance of
TSRA.

Mon-Tues...AM fog/clouds poss. PM -SHRA possible areawide.

&&

.CLIMATE...
Several records were tied or set on Thursday May 2nd:
SITE       OBSERVED TEMP      PREVIOUS RECORD
Altoona         87F             87 in 1954
Harrisburg      90F             88 in 1913
State College   ??*             86 in 1938
Williamsport    89F             89 in 2018

*Official report from State College will be available Friday
 morning.

May 2nd was also the first 90F day at Harrisburg. It is the
13th earliest 90F day on record. The earliest 90F day occurred
on April 17th in 1896 and 2002. The average first 90F day is
June 1st.

&&

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

&&

$$

SYNOPSIS...Dangelo
NEAR TERM...Jurewicz/Dangelo
SHORT TERM...Dangelo/Steinbugl
LONG TERM...Steinbugl/Banghoff
AVIATION...Jurewicz/Evanego/Colbert
CLIMATE...Steinbugl/Banghoff