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109
FXUS61 KCTP 261555
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
1155 AM EDT Sun May 26 2024

.SYNOPSIS...
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Weak high pressure will reside overhead today. A warm front will
lift across the much of the state early tonight, but will likely
stall its progress near or just to the east of the Susquehanna
Valley until later Monday. 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.
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&&

.NEAR TERM /UNTIL 7 PM THIS EVENING/...
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Overnight an early AM Dense fog has eroded/lifted into areas of
stratus. Some of the Central Valley and Western Poconos will be
the last to clear out early this afternoon, but all locations
will see abundant sunshine, warm temps and similar to Saturday,
moderately high dewpoints in the 60s (making it feel a bit
muggy) across Central and Southern PA. Vertical mixing may all
sfc dewpoints to dip into the more comfortable m-u50s across nrn
mtns.

Previous...
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 and a veil of cirrus
spreading in from the west during the mid to late afternoon
should cap things elsewhere, 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.
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&&

.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 /16Z SUNDAY THROUGH THURSDAY/...
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Shrinking areas of IFR/MVFR in the Central Valleys and Middle
Susq Region late this morning will quickly transition to VFR
in all areas by 17Z with VFR conditions prevailing throughout
the rest of the daylight hours. Winds will be range from
5-10kts during the afternoon/early evening 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.
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&&

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

&&

$$

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