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527
FXUS61 KCTP 261123
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
723 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/...
-- Changed Discussion --
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.
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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. So, some SHRA may linger into the first part of the
night, mainly in the far eastern zones.

&&

.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
Medium range guidance all points to a period of cool weather
later next week, as a deep upper level trough pivots southeast
from the Grt Lks. The cold temps aloft should support a daily
chance of diurnally-driven showers, with the highest POPs across
the elevated heat source of the Allegheny Plateau. The best
chance of showers and isolated tsra overall should come with
the passage of a strong shortwave Wednesday. Both the GEFS and
EPS signal dry and warmer weather late next week, as the upper
trough shifts east of PA and Canadian High Pressure builds
southeast into the region.

&&

.AVIATION /11Z SUNDAY THROUGH THURSDAY/...
There is high confidence (> 80%) in a longer duration of LIFR
vsbys/cigs at all airfields across central PA through 12-14Z
outside of MDT/LNS. The bulk of model guidance has continued to
trend back on restrictions across the LSQ airfields, with MVFR-
to-VFR conds. A brief period of lower restrictions are possible
in the near-term with lower cigs, but generally expect these to
resolve quickly back towards MVFR conds through sunrise.

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

HREF guidance has suggested a slightly later arrival of
SHRA/TSRA with the bulk of rainfall expected to enter the
southwestern periphery of the area near 00Z Monday. Generally
low-end VFR to high-end MVFR conds are expected with some
potential for localized restrictions. Low (< 20%) confidence on
these localized impacts keep restrictions after 00Z Monday out
of the 06Z TAF package, outside of LLWS concerns at BFD.

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...
Dense Fog Advisory until 10 AM EDT this morning for PAZ004>006-
010>012-017>019-024>028-033>037-041-042-045-046-049>053-056-
058-063>065.

&&

$$

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