255
FXUS61 KCTP 301834
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
234 PM EDT Sun Jun 30 2024

.SYNOPSIS...
A cold front will push across south-central Pennsylvania
accompanied by scattered showers and thunderstorms. Severe
thunderstorms are possible, mainly east of I-99. A large high
pressure system will build into the region tonight and Monday,
followed by a dying cold front pushing in from the Great Lakes
and stalling out over the area by the middle of next week.

&&

.NEAR TERM /UNTIL 11 PM THIS EVENING/...
Severe to near-severe storms are just ahead of the real dry air
and front. While small showers will pop up on the front over the
next few hours, these will be passing over already-cooled sfcs.
Have started to trim the watch off as the storms move to the
south. CAPE is reaching near 2500 in the sun to the south of the
line of storms. But, there isn`t much convergence with the
hodographs nearly straight lines over the wrn half of the CWA,
now. We should start to see cells over the SErn half of the area
in advance of the main line, and these may have a little
directional shear. All the storms should be off to the SE of the
area around 6-7PM, right around or slightly before ending time
of the watch.

Wind is gusting into the 20s as the dry air invades and temps
have even dropped a little in the NW, and significantly over wrn
NY where JHW is into the 50s with help from the clouds
thickening there.

&&

.SHORT TERM /11 PM THIS EVENING THROUGH 6 PM MONDAY/...
The wind should stay up at least 5KT thru the night everywhere.
Cloud cover should expand a little into the rest of the
Alleghenies early tonight. The dewpoints will be dropping to
45-50F thru the night NW and 50-53F in the SE. Refreshing. Not
much clearing is expected for the wrn highlands, either, so fog
is not a real concern. Mins will be about 50F in the west with a
spot or two in the u40s.

High pressure builds in over the next 30 hrs. Mon should be
sunny after the clouds in the NW dissipate (for the most part).
Wind continues to veer to the N and the dewpoints should drop
even more in the deepest mixing of the day. Td in the m40s
should be common in the wrn half of the CWA in the aftn.

Monday night should be foggy in the nrn and central valleys
despite the dewpoints in the 40s as the air temp should get a
bit lower than the river/creek water temps. Otherwise, light/no
wind under the center of the 1025 high pressure area will help
temps down into the m40s to l50s.

&&

.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
Canadian high pressure builds to southern Ontario by Monday
night, bringing a fair and cool night with the high moving
directly overhead. This will result in efficient radiational
cooling and min temps several degrees below normal. Fair and
warmer weather is expected Tuesday into at least the first half
of Wednesday, as upper level ridging builds over the state and
surface high drifts offshore.

All medium range guidance tracks a weakening shortwave well
north of PA late Wednesday into Thursday. The dying cold front
is likely to sag into the state Thursday and stall out in the
vicinity of PA through Friday. Falling heights/surging low level
moisture ahead of the front could support scattered convection
as early as Wednesday afternoon over the northwest half of PA.
However, a better chance of showers/tsra areawide will come
with the arrival of the front Thu into Friday. Early best guess
of late week rainfall based on ensemble plumes ranges from 0.25
to 0.75 inches, with the highest amounts over the N Mtns and
least in the south.

Heat and humidity should peak ahead of the front Wed-Thu.
Ensemble mean 850mb temps surging to near 20C indicate max temps
could reach the low to perhaps mid 90s in the Lower Susq Valley
Thursday, with high humidity pushing heat indices into the mid
and upper 90s. Ensemble plumes suggest slightly cooler daytime
temps late week, due to more clouds/showers. However, high pwats
in the vicinity of the stalling front should result in muggy
nights and above normal min temps the entire second half of next
week.

Models begin to diverge as we head into the weekend. Most
guidance suggests that rain chances stick around through at
least Saturday as another cold front approaches the area.

&&

.AVIATION /19Z SUNDAY THROUGH FRIDAY/...
Cold front creeping southeast this afternoon, with broken line
of showers and storms just ahead of the front. A few storms
on the strong to severe side, but rather warm aloft has resulted
in limited storms so far. Thus using a TEMPO group for storms.

Winds will continue to pick up some this afternoon, as the
colder air starts to work into the area.

Main thing later tonight will be a period of lower clouds,
mainly across the north and west, but perhaps into the ridge,
valley locations as well. Much less likely to see lower CIGS
across the far southeast.

Any lower CIGS burn off rather fast on Monday morning, and winds
pick up. This based on a very dry airmass working into the area.

Both Monday and Tuesday look dry.

Outlook...

Tue...Dry weather with VFR conditions.

Wed...PM TSRA moving across from W-E.

Thu-Fri..A chance of showers and storms.

&&

.CLIMATE...
At the Altoona Airport, a daily record rainfall of 0.77 inches
was set on Sat, Jun 29. This total breaks the old record of
0.53 inches set back in 1972.

&&

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

&&

$$

SYNOPSIS...DeVoir
NEAR TERM...Dangelo
SHORT TERM...Dangelo
LONG TERM...DeVoir/Bauco
AVIATION...Martin
CLIMATE...Evans/Steinbugl