151
FXUS61 KCTP 031813
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
213 PM EDT Fri May 3 2024

.SYNOPSIS...
-Scattered showers and thunderstorms will begin this afternoon
 mainly in western PA as clouds increase
-Noticeable cool down over the weekend with overcast skies and
 periods of rain
-Remaining unsettled next week with a gradual warming trend

&&

.NEAR TERM /THROUGH TONIGHT/...
The early afternoon hours will remain partly cloudy before
increasing cloud cover into the early evening. High pressure
channeling down the eastern slopes of the Appalachians will
maintain dry wx over the majority of the CWA (eastern 2/3)
through 00Z Sat with max POPs to the west of the US219 corridor.
This area should be in the warm sector where the most unstable
air will reside. A couple of locally heavy t-storm downpours
could produce spot amounts >1" on the west aspect of the
Allegheny Plateau near the edge of higher pwat air surging in
from the upper OH Valley. The WPC D1 ERO covers this area, with
the greatest threat just outside of our CWA (over PBZ) based on
the latest 03/12Z HREF guidance. The 24hr maxTchange will be
considerably cooler over the central and southeastern
ridge/valley region this afternoon with fcst highs giving back
7-15 degrees from yesterdays record challenging to record
breaking temps.

Shower activity should eventually expand west to east through
tonight with a surface boundary stalling out over far western
PA. An increasingly moist east/southeast flow brings widespread
low clouds and perhaps some fog/mist on the ridgetops. The
potential for not severe t-storms remains low given the lack of
instability and the increasing low level stable air with the CAD
setup. Low temps will be above early May climo and range
between 45-55F from the southwestern Poconos/Coal Region to
Warren County.

&&

.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
Hires models show CAD pattern firmly entrenched over CPA on
Saturday, and therefore we continued to trim max temps vs. NBM.
The current thinking is most areas will remain in the mid to low
50s given the easterly flow. No risk of thunder on Saturday so
removed from wx grids and changed character of precip to rain
from showers.

No major changes to the Sunday fcst were made other than
increasing rain PoPs through early Sunday morning. Rain/showers
continue through Sunday and into Sunday night with highs
recovering 5-10F over the southwest 1/2 of the CWA. Some
isolated convection is possible in this area Sunday PM as the
warm sector shifts to the east. Despite the relatively high
moisture availability, limited rain rates should keep blended
mean QPF btwn 0.50-1.00 inches ending 00Z Monday. Fcst lows
Sunday night will be +10-15F above climo for early May in the
50-60F range.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
The long term period will be dominated by WSW flow aloft. Sfc
boundaries linger overhead/nearby the state for the entire
period. Several successive shots of shortwaves should slide
overhead, likely the remnants of a very active/stormy time over
the central plains. Thankfully, the expected severe weather in
the middle of the country is not expected to extend this far to
the east on most (if any of the) days. However, we do get the
forcing provided by the repeated MCSs. These things are highly
difficult to track and anticipate the timing of arrival, too,
4-7 days out. The ECMWF does push the boundary south of PA
enough for Tues to be dry. But...the GFS and importantly, the
blend of models, never let go of 30-80 PoPs. Gulf moisture
really never gets totally cut off from reaching the OH
Valley/Mid-Atlantic States, but does diminish somewhere in the
vicinity of PA. Thus, there is high confidence of a wet period
during the entire long term, esp for srn PA, but extremely low
confidence in timing of each successive wave. PoPs >30pct will
remain for each 12hr period, as there is no model or conceptual
consensus to dip that low. They also won`t go above 80 pct for
much the same reason.

&&

.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
Heating popping a few taller cu from N of IPT to UNV to JST. So,
much of the area should be VFR for the next 6-12 hrs. None of
these have more than the faintest of returns on radar at 18Z. A
strong shortwave/area of positive forcing is approaching from
the west and is carrying a broach patch of SHRA but no TS just
yet. Outflow boundary moving toward BFD from the NW and earlier
convection has dropped the temps and turned the wind to the
N/NW over NErn PA (ERI/GKJ) already. Only small cu are seen
along the boundary as it moves southeastward early this aftn.
The heating of the day should provide just enough kick to help
storms occur in wrn PA (perhaps even into JST and BFD before
21Z). The stability in the lowest 5kft overhead should keep
storms from moving too deep/far eastward into the central mtns
(UNV/AOO). We have fairly high confidence in a no TS fcst for
IPT/MDT/LNS at this point. Still, the SHRA do progress eastward
all night, and may make it into those terminals by 12Z. Have
only mentioned VCTS for BFD and JST at this point with low
(30pct) confidence that they will have a TSRA for long enough to
justify a categorical period with TS occurring as the prevailing
wx type.

Low clouds and some fog will develop in many places overnight
due to increasingly humid air and a near-constant SErly llvl
wind. LIFR looks probable (80%) at JST and IFR probably (80%) at
BFD, AOO, UNV beginning in the middle to latter period of the
night. Will hold off on mentioning any IFR cigs/vsby at the
eastern terminals for now.

Sat looks unsettled, too. Widespread light SHRA are expected for
the srn terminals for all of Sat, and the IFR may linger for the
SWrn terminals and may creep into MDT/LNS, too. BFD may actually
be the best location for flying into/out from on Sat when
compared to the other central PA terminals.

Outlook...

Sun...Widespread restrictions due to low cigs. SHRA likely with
a chance of TSRA.

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

&&

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

&&

$$

SYNOPSIS...Steinbugl/Bowen
NEAR TERM...Steinbugl/Bowen
SHORT TERM...Steinbugl/Bowen
LONG TERM...Dangelo
AVIATION...Dangelo