179
FXUS61 KCTP 141423
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
1023 AM EDT Fri Jun 14 2024

.SYNOPSIS...
A cold front over the Great Lakes will push southeastward
across Pennsylvania this afternoon into this evening,
accompanied by showers and thunderstorms. This front will be
followed by Canadian high pressure building in for this weekend,
bringing lower humidity. After that, the big story will be
building heat as a subtropical ridge builds over the eastern
United States next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
A batch of showers is breaking out across the central mtns and
middle Susq Valley late this morning, so have upped PoPs there.
Already seeing showers/storms pop up over western PA, and this
activity will continue to expand and make it`s way eastward
into central PA this afternoon.

Model guidance pushes the upper trough and associated cold
front through Central PA this afternoon/evening, accompanied by
showers and thunderstorms. Diurnal heating of a relatively
moist pre-frontal air mass, combined with strong large scale
forcing ahead of a potent shortwave diving into the base of the
approaching trough, will result in an uptick in convection
along the front as it pushes into the area this aftn. Modest
instability and deep layer shear approaching 40kts supports
organized convection this afternoon with a chance of isolated
severe weather along the I-80 corridor and the Lower Susq
Valley, where HREF UH values are >75. The bulk of convection-
allowing guidance indicates the greatest risk of severe weather
will progress from the Central Mtns between 17Z-19Z, to the Susq
Valley between 19Z-21Z.

Strong large scale forcing ahead of the upper trough and
seasonably high pwats support likely POPs this aftn across much
of Central PA. Ensemble plumes indicate just a few tenths of an
inch rainfall for most locations, although localized 1-2+"
amounts are possible in any persistent downpours.

Any evening showers/tsra should exit the Lower Susq Valley by
late evening, as the cold front pushes east of the
commonwealth. High pressure building in behind the front should
bring clearing skies, cooler air and lower humidity overnight.

&&

.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
Canadian High Pressure building southeast into PA will bring
fair weather this weekend, with abundant sunshine and seasonably
warm days. However, ideal conditions for radiational cooling
appear likely Sat night under the surface high, resulting in
min temps several degrees below mid June normals. Expect
daybreak readings to range from the mid 40s over the N Mtns to
mid 50s across the Lower Susq Valley. Very dry air above a weak
inversion in the model soundings suggest dewpoints will fall
below NBM guidance, especially Saturday, so have leaned toward
the drier MAV guidance.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
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 to +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. Tuesday will
likely be the warmest day with most guidance showing a 597+ dm
ridge centered over or just to the east of the area. With the
surface high off to the east, southerly flow will usher in
higher dew points that will allow for heat index values to
reach 100-105 degrees over a large portion of the area. Humid
conditions will continue into Wednesday and Thursday with
anomalously warm conditions continuing into the end of the week.

&&

.AVIATION /14Z FRIDAY THROUGH TUESDAY/...
A cold front nearing the south shore of Lake Erie at 1130Z will
drift southeast across Central PA during the afternoon and
early evening hours. A few bands of showers and embedded TSRA
will occur in advance and along this airmass boundary with
periods of MVFR and possibly brief IFR VSBY and CIGS (30 percent
chance of brief IFR occurrence) in the more intense TSRA.

Brief wind gusts AOA 40 kts area also possible, along with some
isolated instances of hail.

Showers and storms are expected to taper off from late this
afternoon (NW Mtns) into the evening (SE Airfields including
KMDT and KLNS).

A second round of enhanced upper level forcing may slow the
front and delay the end to the convection by a few hours
across the far south and east this evening.

Employed a TEMPO group later today to cover any storms with
brief gusty winds.

A few hour period of LLWS is likely across the Lower Susq Valley
this evening with a 30-35 kt NNW wind max in the 2-3 kft layer
in the wake of the CFROPA.

A splendid and seasonably warm weekend is on tap with abundant
sunshine and dewpoints in the mid 40s to lower 50s as drier air
builds into the region from the north. Winds will be northerly
and mainly under 10 KTS on Saturday before shifting to the south
and southeast on Sunday.

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
LONG TERM...Bauco/NPB
AVIATION...Lambert