277
FXUS61 KCTP 261514
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
1114 AM EDT Sun May 26 2024

.SYNOPSIS...
Weak high pressure will reside overhead today. A warm front will
lift across the state early tonight. Low pressure will pass
over the Upper Great Lakes on Memorial Day, dragging a cold
front through late Monday/evening. An upper level trough will
build into the region for the remaining portion of the week.

&&

.NEAR TERM /UNTIL 7 PM THIS EVENING/...
Early AM Update holds just some tweaks to sky cover for today to
allow for more clouds in the nrn half with the fog/stratus
likely hanging on there longest. The fog advy still looks good
with the first visible shots of the day showing the widespread
coverage of the fog (and very low stratus). Visby has improved
slightly since first light here at the office. Neat lee/wave
action in the clouds also seen in the vis images/loop downwind
of the mtns. There is a light nrly flow just above the
extremely stable lowest 1-2kft.

Prev...
Widespread dense fog is covering most of the area this morning.
Most of the area is under a dense fog advy thru 14Z. Even with
the sunrise is earlier and earlier each day, this is a big patch
of fog and very low clouds to burn away too quickly. Some places
may still have a little fog by 11 AM or Noon. While the far SE
has very low clouds, most places there have not yet dropped the
visby below 4SM yet. But, they will probably (70% chc) have the
fog get bad enough for an advy there, too. Will issue as needed.

After the fog burns off, much of the area will remain mostly
sunny for the balance of the day. Tall cu, and isold/sct SHRA
are possible in the srn tier and Poconos this aftn. There could
be a ltg bolt or two, just enough of a chc to make mention in
the grids. A layer of slightly milder air from 8-12kft over the
area could cap things, at least enough to keep TS away. Max
temps will reach the u70s on top the nrn mtns and the Laurel
mtns, but 80s elsewhere. It will be muggy in the S where
dewpoints don`t dip for the aftn (stay in the 60s). Dewpoints
should dip into the m50s or lower in the nrn mtns, so it will
feel more comfortable.

&&

.SHORT TERM /7 PM THIS EVENING THROUGH 6 PM MONDAY/...
Some fog may again form early tonight. But the invading and
thickening clouds and showers/storms due to the first of a few
pre-frontal troughs will probably preclude it from getting
thick, and the precip may actually bring the visby back up if it
does go down. The forcing tonight likely makes a long band of
showers/storms cross the area from SW-NE in the evening and
first half of the night. More nebulous forcing then exists for
3-6hrs before the next wave of forcing moves in from the west.
late night timing is against much thunder with the second batch
of precip. That precip will still be crossing the eastern half
of the area in the morning/daylight hours. This could stabilize
things for the first part of the afternoon there. But, the west
will likely have enough breaks in the clouds and moisture to be
able to cook up good CAPE for the early aftn, and TSRA will pop
up. This third batch of storms is the most likely to produce
some severe wx. The SPC SLGT risk covers all the srn half of
the CWA for Day2, and CAPE may be <=2000J. Main threat is wind,
but 1" hail also a threat. The tor threat is mainly along the MD
border where the hodographs get fattest and high mstr will keep
the LCLs lowest. PWAT goes above 1.5" (approaching 2") in the
eastern half of the area in the late morning and aftn hours. The
repeated shots of rain will lead to a risk of flash flooding
over much of the area on Monday, but mainly in the east in the
aftn. The strong surface low will move northeast across the
Upper Great Lakes and into ONT. Two pushes of drier air and a
gradual veer to the wind is expected in the evening and
overnight.

&&

.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
Once any lingering showers/storms pull east of the area Monday
evening, drier air will begin to filter in behind the departing
front.

Medium range guidance continues to point to a period of cool
weather Tuesday through Thursday, as a deep upper level trough
pivots southeastward from the Great Lakes. Cold temps aloft
should support a daily chance of diurnally-driven
showers/storms, with the highest POPs across the elevated heat
source of the Allegheny Plateau. The best overall chance of
showers should come with the passage of a strong shortwave
on Wednesday.

We should see a transition to drier and warmer weather Friday
into Saturday, as the upper level trough axis shifts east of PA
and high pressure builds into the region. An approaching frontal
system could bring our next round of showers/storms by next
Sunday.

&&

.AVIATION /15Z SUNDAY THROUGH THURSDAY/...
Restrictive conditions are expected to improve by mid-morning
(~14Z Sunday, +/-1hr) with VFR conditions prevailing throughout
the day. Winds will be range from 5-10kts during the daytime
hours with gusts upwards of 15kts along ridgetop locations.

Guidance suggests SHRA/TSRA entering the southwestern periphery
of the area near 00Z Monday and overspreading the entire area
through 12Z. Generally low-end VFR to high-end MVFR conds are
expected with some potential for localized restrictions.
Guidance has started to suggest some timing of localized
restrictions, but given low (~20%) confidence and little
temporal continuity in guidance runs, have opted to keep these
restrictions minimal in this TAF package.

Conds will continue to trend towards MVFR/IFR conds near and
after 06Z. There is some concern for a return to LIFR/IFR conds
overnight tomorrow night across eastern PA where some hints
towards enhanced low-level moisture, but have opted to keep
these concerns out of the TAFs until further model consistency
is achieved.

Outlook...

Mon... Persistent restrictions are expected in widespread
showers and thunderstorms.

Tue-Wed...Brief restrictions are possible in scattered showers,
but much of the time should be VFR.

Thu...Predominantly VFR.

&&

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

&&

$$

SYNOPSIS...Fitzgerald/Dangelo
NEAR TERM...Dangelo
SHORT TERM...Dangelo
LONG TERM...Fitzgerald/Evanego
AVIATION...NPB