327
FXUS61 KCTP 131901
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
301 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 11 PM THIS EVENING/...
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.

&&

.SHORT TERM /11 PM THIS EVENING THROUGH SUNDAY NIGHT/...
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.

All 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 upper 40s and low 50s. This
will be the last time we see temperatures in the 40s in PA for
the foreseeable future.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
Dry conditions are expected to prevail through Tuesday
afternoon. There is some potential for diurnally-driven
showers/storms across the northern tier on Monday afternoon, but
model guidance has backed off slightly in recent runs, so have
capped below a slight chance (10-15%) at this time. Slightly
higher probabilities emerge in the afternoon hours of Tuesday
through Wednesday across the northern tier before becoming more
areawide on Thursday. At this time, have capped any
precipitation mentions to a slight chance (15-25%) during the
afternoon hours.

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.

&&

.AVIATION /19Z THURSDAY THROUGH TUESDAY/...
18z update... VFR/unrestricted conditions are expected to last
for the rest of the daylight hours and through much of the
overnight period, as well. There is an outside chance (only
10-20%) of a stray shower/thunderstorm late this afternoon in
the vicinities of KMDT and KLNS.

Later tonight/early Friday, as a cold front approaches, lower
clouds and a band of showers/thunderstorms will approach the
Commonwealth from the NW. Our highest confidence of potential
restrictions is at KBFD and KIPT, and those two sites are where
we have prevailing showers and the mentions of vicinity TSRA.

Our current expectations are that any restrictive conditions
from showers and thunderstorms will not reach KJST, KUNV, KAOO,
KMDT, and KLNS until after 18z Friday.

Outlook...

Sat-Sun...Predominantly VFR.

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

&&

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

&&

$$

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