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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KCTP 131049
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
649 AM EDT Thu May 13 2021

.SYNOPSIS...
-- Changed Discussion --
High pressure centered over the midwest will drift east across
Pennsylvania by this weekend. The high will pass off the east
coast early next week, with a warm front potentially lifting
into the state by the middle of next week.
-- End Changed Discussion --

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
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After a chilly and sunny start to the day, expect a fair amount
of diurnal cumulus in response to upper trough over the region.
Much as occurred yesterday, expect just enough instability to
support isolated, light showers/sprinkles during the afternoon
over the elevated terrain of the Alleghenies.

Have undercut NBM temps slightly today based on an expectation
of a fair amount of afternoon cumulus and 850 temps of 4-5C,
which supports highs ranging from around 60F over the Allegheny
Plateau and the upper 60s across the Lower Susq Valley.
-- End Changed Discussion --

&&

.SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY/...
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Surface high will slowly build into the region tonight,
supplying another night of fair and chilly conditions. However,
the Canadian air mass associated with this feature should
continue to modify, resulting in low temperatures several
degrees above those of this morning. Still, patchy frost will
likely be a concern over the northwest mountains.

Pennsylvania will remain under the influence of a mean upper
level trough Friday, resulting in the chance of isolated PM
showers. It looks like there will be a better chance of showers
Saturday afternoon, when models track a shortwave directly over
the state during max heating of the afternoon.

The cool weather of the last several days should transition to
near average temperatures by this weekend, as the Canadian high
pressure system continues to moderate and slide east over Pa.
-- End Changed Discussion --

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
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On the large scale, the blocky pattern that we`ve had in the
northern stream, featuring a persistent closed upper high over
south-central Canada and a trough axis/lower heights extending
from eastern Canada into the northeastern CONUS, should
gradually open up and become more progressive. The main impact
of this transition will be warmer, more seasonable temperatures
over time for central PA.

The combination of cool temperatures aloft and still residual
short-wave energy from the aforementioned trough axis as it
lifts out/weakens will produce isolated and diurnally enhanced
convection once again on Sunday. However, limited overall
coverage means the majority of us will stay dry. Fairly weak
flow over a deep layer of the atmosphere may also anchor any
isolated convection that forms mostly to terrain features.

Early next week, as a low-level warm front slowly approaches
from the southwest and more moisture gets injected into the
atmosphere locally, we should see at least somewhat increased
coverage for shower activity.

As alluded to earlier, temperatures will be moderating back
towards seasonal normals for central PA, with daily highs
ranging from the upper 60s-mid 70s and nighttime lows in the
40s-lower 50s.
-- End Changed Discussion --

&&

.AVIATION /12Z THURSDAY THROUGH MONDAY/...
High pressure will very slowly build in from the west through
the next few days bringing mostly dry conditions. Light wind
this morning, followed by some diurnal cu and an increase in
wind from the N for the aftn. A sprinkle or two is expected over
the Alleghenies as a short wave trough passes overhead again.

Fri aftn may hold a few more SHRA, but most/all of the time
should be VFR. Any flight category reductions will likely hold
off until Sat aftn when diurnal convection looks like it will be
more organized and dewpoints/moisture higher.

Outlook...

Fri-Sun...VFR. A few SHRA possible each aftn, mainly over the
central mtns.

Mon...VFR. SHRA poss, mainly S.

&&

.CLIMATE...
The record low temperature for Thursday morning (5/13) in State
College is 31 degrees. The mercury will likely fall several
degrees shy of that value.

&&

.CTP WATCHES/WARNINGS/ADVISORIES...
Frost Advisory until 8 AM EDT this morning for PAZ004>006-
010>012-017>019-024-025-033-034-037-041-042-045.

&&

$$
SYNOPSIS...Fitzgerald
NEAR TERM...Fitzgerald
SHORT TERM...Fitzgerald
LONG TERM...Jurewicz/Colbert
AVIATION...RXR/Colbert
CLIMATE...