401
FXUS61 KCTP 262326
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
726 PM EDT Wed Jun 26 2024

.SYNOPSIS...
*Showers and thunderstorms with locally heavy rainfall will
 settle southward to the Mason Dixon line by midnight.
*Partly to mostly sunny and less humid Thursday and Friday
*Return of summertime heat+humidity will fuel thunderstorms for
 the last weekend of June; seasonably cooler & dry start to July

&&

.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
725PM EDT: Remainder of SVR WW #464 cleared from central PA at
this time.

Evolution from discrete and training cells to broken and bowing
convective line segments occurred over the past 2 hours, with
the most intense convection exiting to our east. Hires models
show rain and storms progressing from northwest to southeast
btwn 00-06Z with a general weakening trend expected as BL
stabilizes after sunset. Main question is how much recovery
occurs over southern half of central PA this evening, with
consensus that it will be hard to destablize sufficiently to
support intense convection. Showers and isold tsra should move
across those areas late this evening through around midnight
with decreasing activity after midnight.

As the frontal zone sags southward this evening, we`ll be
watching heavy rain potential as southwest to northeast storm
motion and slow southward movement of the overall boundary may
bring much needed rain to many areas south of I-80. CAMs
indicate most numerous showers/storms settle south of the Mason
dixon line after 06z.

&&

.SHORT TERM /6 AM THURSDAY MORNING THROUGH FRIDAY NIGHT/...
Large scale subsidence and the arrival of much drier (less
humid) air behind the exiting cold front will lead to fair and
seasonable conditions Thursday. Surface high pressure building
over the region should result in fair and cool weather Thu night
with valley fog formation likely given air/water spreads 20-30
degrees. Partly cloudy and slightly warmer conditions are
likely Friday, as low pwats persist over PA and a return
southerly flow develops as the surface high passes off the
coast. Latest model data suggests some showers and storms may
develop Friday night over the western portion of the forecast
area.

&&

.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
Latest medium range guidance is showing an unusual lack of
spread among its members, all of which track a surface low
north of PA Saturday, with a trailing cold front coming through
Sat night into early Sunday. The lack of spread with regards to
timing of the front, combined with progged GEFS pwats of
+2-3SD, supports an increasing confidence in showers/tsra
Saturday. A leading warm front could produce showers/tsra as
early as Friday night and a slowing cold front could cause
convection to linger into Sunday, mainly over the southeast
counties. However, ensemble plumes indicate the most widespread
convection should occur Sat afternoon and evening.

There is some potential for severe wx Saturday PM, as decent
mid level flow overspreads an increasingly moist warm sector.
Ensemble plumes currently indicate moderate capes in the 1000
J/kg range and model 0-6km shear is in the 35-40kt range.
If the cold front slows enough, severe wx would also be possible
across the eastern edge of the forecast area Sunday PM.

Latest EPS and GEFS both support fair weather with near to
slightly below normal temps and low humidity early next week
associated with high pressure building east from the Grt Lks. A
seasonably cool and dry start to July!

&&

.AVIATION /00Z THURSDAY THROUGH MONDAY/...
VFR conditions across Central PA at midday, but thunderstorm
chances increase into the evening hours. A few of these storms
could be strong to severe with any impacted TAF site likely to
see high wind gusts and briefly lowered visibility.

Tstms already popping up over NW PA with convective impacts in
the vicinity of BFD and occasional impacts/reductions at the
airfield through around 21z. Convective activity picks up later
in the afternoon for the central mountains stretching from JST-
AOO-UNV-IPT. An isolated tstorm is poss in the vicinity through
21-22z, with likely impacts/reductions from tstms moving across
the airfields around 00z. Similar setup over the SE where an
isolated storm will be possible through 00z near MDT-LNS ahead
of better likelihood of impacts after 00z.

As the showers and thunderstorms exit to the east during the
late evening, guidance indicates the potential for low clouds to
stick around across a large portion of the area. The HREF shows
the highest probabilities of IFR ceilings (50-60%) at BFD and
JST, with lower probabilities of MVFR ceilings at all other
sites except MDT and LNS.

Outlook...

Thu-Fri...Generally VFR.

Sat-Sun...Thunderstorm impacts possible.

Mon...Generally VFR.

&&

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

&&

$$

SYNOPSIS...DeVoir/Steinbugl
NEAR TERM...DeVoir/Steinbugl
SHORT TERM...Lambert/Fitzgerald/Steinbugl
LONG TERM...Fitzgerald/Steinbugl
AVIATION...Bauco/Bowen/RXR