447
FXUS61 KCTP 032302
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
702 PM EDT Wed Jul 3 2024

.SYNOPSIS...
Warm and humid conditions will prevail through week`s and into
the start of the coming weekend. A weakening cold front will
push in from the Great Lakes tonight, then stall out over the
area late this week. Low pressure tracking north of Pennsylvania
will drag a cold front through the state Saturday. Drier and
more comfortable conditions are expected for Sunday.

&&

.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
The focus tonight will be on a an approaching, slow-moving cold
front, which lies from near Detroit into Northern Indiana at
22Z. Diurnal heating ahead of the front has resulted in a band
of convection along the attendant low level jet/plume of highest
pwats from the Ohio Valley into Northwest PA. Expect the
prefrontal convection to make slow eastward progress overnight
and diminish in coverage/intensity with loss of heating. Latest
convection-allowing guidance supports a good chance of showers
and isold tsra across the NW Mtns tonight, but little chance of
any rain reaching the Lower Susq Valley. By dawn, the best
chance of showers will likely be in the vicinity of the surface
cold front, which is progged to be entering the N Mtns by that
time.

Surging pwats ahead of the cold front, combined with modest
instability, could support some locally heavy downpours later
this evening over the extreme northwest part of the forecast
area (Warren Co). Otherwise, rainfall amounts should generally
remain light, with most locations southeast of the Allegheny
Plateau remaining dry. Mostly cloudy skies over the northwest
counties and increasing clouds elsewhere, combined with surging
humidity, will result in a much warmer night than we`ve seen
recently, with low temperatures in the mid 60s to lower 70s.

&&

.SHORT TERM /6 AM THURSDAY MORNING THROUGH SATURDAY NIGHT/...
The front will slowly sag across the area on Thursday, with a
mostly cloudy day in store for the Fourth of July and even
muggier conditions as dewpoints reach the lower 70s in some
spots. Morning showers and storms associated with the decaying
cold front will gradually move southeast through the day and
should remain scattered in coverage. The front will be located
over southern PA by Thursday afternoon, which is where most of
the shower activity should be concentrated for any 4th of July
and/or fireworks festivities. Highs on Thursday afternoon will
generally be in the 80s with a few spots potentially reaching 90
degrees in the southeast before convection arrives.

Severe and excessive rainfall risks remain low on Thursday, with
SPC MRGL clipping portions of my southern tier counties THursday
afternoon/eve. Rain is greatly needed in areas that have the
highest POPs Thursday afternoon. Any stronger storms could
produce gusty winds and potentially a downburst, but this seems
contingent on there being some breaks in the clouds to fuel
potential intstability. As mentioned previously, bulk shear
near the front will be sufficient for organization, but CAPE may
be lacking owing to persistent cloud cover. Regardless, the
chance of showers and storms should be monitored for anyone who
plans to take part in outdoor festivities to celebrate
Independence Day.

The front is progged to stall out in the vicinity of Southern
PA Thursday night, then return north as a warm front Friday
ahead of low pressure lifting across the Grt Lks. Falling
heights and surging pwats ahead of an upstream shortwave and
associated surface low lifting across the Grt Lks should bring a
round of showers/tsra in the Friday PM to Saturday timeframe.
Current guidance suggests the shortwave and bulk of the large
scale forcing will pass north of PA, leading to unimpressive
mean qpf in the ensemble plumes of 0.25 to 0.50 inches Fri PM to
Saturday.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
Deterministic guidance continues to outline fair and seasonable
conditions on Sunday and into early Monday with surface ridging
and drier air working in behind the frontal passage. There is a
bit of uncertainty into the later hours on Monday as ECMWF
guidance outlines drier conditions prevailing across all of
central PA, with GFS outlining some showers and thunderstorms
Monday late afternoon/evening across mainly southern
Pennsylvania where moisture and lift will be slightly more
favorable. Given some uncertainty, have mainly kept PoPs
confined along the Turnpike and the higher elevations of
Schuylkill County for this forecast cycle, slightly cutting back
from NBM PoPs in this timeframe.

Both ENS and GEFS plumes begin to outline greater chances for
precipitation into Tuesday, as a low pressure north of the area
continues to push eastwards and drag a cold front across the
region. Some instability will bring some potential for storms
especially in the afternoon/evening hours, but cannot rule them
out throughout the morning hours during this forecast cycle.

&&

.AVIATION /00Z THURSDAY THROUGH MONDAY/...
VFR conditions will prevail with moderate (50-60%) confidence
this evening with southerly flow gusting 15 to 20 knots. A cold
front will approach tonight and lay out W-E over the state on
Thursday. The deep moisture Wednesday PM and Thursday will
allow for scattered to numerous showers and thunderstorms.
Outlined KBFD/KJST with SHRA/VCTS due to the development of the
complex currently south of KCLE moving eastward. The first batch
of showers is expected to fizzle as it moves southeast through
tonight, with additional showers and storms developing in the
humid environment on Thursday, especially south of KBFD.

The 18Z package outlines potential for IFR conditions based on
low cigs in the 10-16Z where increased low-level moisture
coupled with calm-to-light winds late overnight. Lower
confidence (30-40%) on IFR conditions prevailing, due to some
residual cloud cover and/or rain narrowly missing the airfield.
There is lower confidence on exact coverage and placement of
SHRA/TSRA on Thursday, thus have kept it out of the 18Z TAF
package.

Outlook...

Fri...Sct TSRA w/ possible impacts; Mainly PM w/ highest
coverage across the west.

Sat...Sct to Nmrs TSRA areawide, highest chances SE in PM.

Sun...AM fog possible; otherwise, no sig wx.

Mon...SHRA possible SE late PM; otherwise, no sig wx.

&&

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

&&

$$

SYNOPSIS...DeVoir/Fitzgerald
NEAR TERM...Fitzgerald
SHORT TERM...DeVoir/Fitzgerald/Banghoff
LONG TERM...Fitzgerald/NPB
AVIATION...NPB