-- Discussion containing changed information from previous version are highlighted. --
316
FXUS61 KCTP 132302
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
702 PM EDT Thu Jun 13 2024

.SYNOPSIS...
High pressure will pass off of the Mid Atlantic coast today, as
a cold front pushes into the Great Lakes. This front will cross
Pennsylvania on Friday, followed by Canadian high pressure
building in for this weekend. An anomalous subtropical ridge is
likely to build over the East Coast next week, bringing
increased heat and humidity.

&&

.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
Surface high pressure will drift off the Mid Atlantic coast
today, resulting in a warmer southwesterly flow.

Cu is quickly developing over the Lower Susq Valley in a
slightly muggier airmass (sfc dewpoints in the mid 60s). Can`t
rule out a late day shower/tsra down there, as models indicate
surging pwats and capes topping out near 1000 J/kg. Dry mid
level air in the model soundings, however, suggests that any
convection will be spotty.

Mixing down model 850mb temps of around 16C this aftn translates
to highs ranging from around 80 degrees along the spine of the
Appalachians to the upper 80s in the Susq and Cumberland
valleys.

Falling heights and surging low level moisture ahead of an
upper level trough working into the Grt Lks could spread a
shower into the N Mtns late tonight. Otherwise, fair weather is
anticipated, with markedly milder conditions than recent nights
in the warm advection regime ahead of the trough. Mostly clear
skies, light wind and rising dewpoints may lead to some patchy
late night valley fog in the central part of the state per
latest SREF prob charts.

&&

.SHORT TERM /6 AM FRIDAY MORNING THROUGH SUNDAY NIGHT/...
Model guidance pushes the upper trough and associated cold
front through Central PA Friday, accompanied by a good chance of
showers and possible tsra. Precip is expected to hold off until
afternoon across the southeastern half of the forecast area,
allowing temps to rise above seasonal normals, while an early
arrival of showers is likely to cap max temps in the low to mid
70s across the N Mtns. Modest instability and decent mid level
flow supports a chance of isolated severe weather Friday
afternoon over the southeast part of the forecast area, where
HREF UH values >75 supports organized convection. SPC has
highlighted the southeastern third of PA with a SLGT risk for
severe storms, with the primary threat being from potentially
damaging wind gusts.

Strong large scale forcing ahead of the upper trough and
seasonably high pwats support POPs in the 60-80pct range Friday
over most of Central PA. Latest ensemble plumes indicate just a
few tenths of an inch rainfall for most locations, with isolated
1-2+" amounts in any storms.

Any evening showers/tsra over the southeast counties should end
shortly after sunset Friday, as the cold front exits the state.
Canadian high pressure building in behind the front should
bring clearing skies and cooler air Friday night.

Abundant sunshine and seasonal temps are expected Saturday, as
the high pressure system and associated low-pwat air mass builds
into the region. The center of high is progged to pass over
Central PA Saturday night, resulting in favorable conditions for
radiational cooling and low temperatures in the 40s and low
50s. This will be the last time we see temperatures in the 40s
in PA for the foreseeable future...

Dry conditions are expected to prevail into Sunday, with
temperatures beginning a moderating trend that will continue
into next week.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
-- Changed Discussion --
An extended period of above average temperatures is increasingly
likely as a large ridge builds across the eastern US. This will
allow for MaxTs and MinTs +10-15F above climatology for the
middle of June. Model differences have become slightly better
resolved with respect to the strength of the ridge, outlining
higher confidence of abnormally warm temperatures extending
northward into PA.

Less humid conditions on Monday will bring heat index values
into the mid-to-upper 90s, with some valley locations across
central/southern PA pushing close to the 100F mark. Humidity
during the afternoon hours will increase the risk for excessive
heat on Tuesday with some potential for heat index values in the
100-105F across the Lower Susquehanna Valley. Humid conditions
will continue into Wednesday and Thursday with anomalously warm
conditions continuing into the end of the week.
-- End Changed Discussion --

&&

.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
-- Changed Discussion --
For the 00Z TAF package, looking at a dry evening so far. One
small shower formed for a couple of minutes earlier just before
6 PM, but is gone now.

Later tonight/early Friday, as a cold front approaches, lower
clouds and a band of showers/thunderstorms will approach the
Commonwealth from the NW. Expect the activity to weaken as it
heads southeast late.

Models still trying to form a band of showers that could edge
into the far southeast later tonight, but so far, not sign of
anything. Temperatures on the warm side, but not all that humid
for shower formation.

Showers and storms work to the east and south on Friday, with
some potential for gusty winds with storms. This will depend on
the amount heating, timing of the activity, and the amount of
phasing with the lee side trough.

Still expect showers and storms to taper off from late afternoon
into the evening. Upper level forcing may result in the activity
across the far south and east to be slow to taper off.

Anyway, used a TEMPO group later Friday to cover any storms with
brief gusty winds.

Clearing out nicely over the weekend, as drier air builds into
the region from the north.

Outlook...

Sat-Sun...Predominantly VFR.

Mon and Tue...Mainly VFR. Isolated afternoon/evening TSRA
possible, with any restrictions brief in nature.
-- End Changed Discussion --

&&

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

&&

$$

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