813
FXUS61 KCTP 140939
AFDCTP

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

.SYNOPSIS...
A cold front over the Great Lakes will push southeast across
Pennsylvania later today, followed by Canadian high pressure
building in for this weekend. An anomalous subtropical ridge is
likely to build over the East Coast next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
Falling heights and surging pwats ahead of an upstream trough
will bring the chance of a shower to the northern half of PA
early this morning. However, the bulk of the forcing associated
with a lead shortwave is passing well north of PA, so kept POPs
<25pct.

Model guidance pushes the upper trough and associated cold
front through Central PA this afternoon, accompanied by a good
chance of 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, should result in an uptick on
convection along the front as it pushes into the I-80 corridor
during early afternoon. 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 high POPs in the 60-90pct range
today over most of Central PA. Latest ensemble plumes indicate
just a few tenths of an inch rainfall for most locations, with
the HREF LPMM supporting the possibility of isolated 2+ inch
amounts along the I-80 corridor, where progged instability is
greatest.

Any evening showers/tsra should exit the southeast part of the
forecast area by late evening, as the cold front pushes east of
the state. High pressure building in behind the front should
bring clearing skies and cooler air the rest of tonight.

&&

.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 /10Z FRIDAY THROUGH TUESDAY/...
A cold front over the Lower Great Lakes early this morning 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 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.

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.

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

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
NEAR TERM...Fitzgerald
SHORT TERM...Fitzgerald
LONG TERM...Bauco/NPB
AVIATION...Lambert/Martin