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000
FXUS61 KCTP 171104
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
704 AM EDT Wed Apr 17 2024

.SYNOPSIS...
-Mostly cloudy with periods of rain through Friday
-Marginal severe t-storm & flooding risk late this afternoon
 into the early evening primarily west of the Allegheny Plateau
-Weekend cool down; monitoring frost/freeze risk Saturday-Monday

&&

.NEAR TERM /THROUGH TONIGHT/...
Strong low level theta-e advection ahead of warm front in the
upper OH Valley this morning will be followed by falling
heights and surging PWATs 1-1.5" associated with upper
shortwave and occluded front will bring periods of light to
moderate rain to CPA today into tonight. QPF forecast through
8PM is between 0.10-0.25 inches.

The primary severe t-storm and heavy rain/flooding risk will be
confined to areas along and mainly to the west of the Allegheny
Plateau where best combo of instability, shear, and low FFG will
align late this afternoon into the evening. Elevated MUCAPE will
support mention of t-storms over all of CPA tonight, but increased
low level stability, lower intensity rain rates, and progressive
precip movement will greatly limit/preclude these risks farther
to the east over the majority of the CWA.

Max temps grids have strong CAD resemblance with a 15 to 20
degree gradient from southwest to northeast PA. Mild tonight
with lows in the 45-55F range. Some fog and drizzle is likely
late tonight into early Thursday morning across east-central PA.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
Rising heights noted in the model guidance Thursday, as the
remnants of the upper low pass well north of PA and the plume of
deep moisture shifts east of the forecast area. Residual low
level moisture, combined with upslope flow, may yield a bit of
lingering drizzle, mainly over the N Mtns and W Poconos, where
model sfc-850mb remains near 100pct. At the surface, a slow-
moving occluded front is progged to push into the central
portion of PA. A drier westerly flow behind it should result in
partial clearing. However, a lingering inversion in the model
soundings suggests afternoon showers are unlikely.

Most model guidance indicates a closed upper low will pass north
of the region Friday, with a trailing occluded front coming
through Central PA Friday afternoon/evening. The triple point
low is progged to pass south of the forecast area, so the severe
weather threat looks very low. A decent plume of moisture with
pwats close to +2SD should support POPs close to 100pct and some
heavier showers. However, the best large scale forcing as
inferred by model 300-500mb qvec convergence fields passes well
north of PA, so expect overall rainfall to be less than
impressive. Latest plumes support amounts between 0.1 and 0.2
inches in general.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
Upper level troughing in the the latest EPS/GEFS supports
slightly below average temps through the weekend. Surface
ridging and low-pwat air building into PA should result in dry
weather Sat/Sun with afternoon dewpoints likely a bit below NBM.
Light wind, dry air and mostly clear skies associated with the
surface ridge is likely to result in areas of frost Saturday and
Sunday nights. The risk of frost is greatest over the N Mtns,
but areas in the growing season further south could also be
affected.

Moderating temps are expected by Tuesday, as the surface high
slips off of the east coast. However, and approaching
shortwave/cold front will bring the next chance of showers by
Tue PM.

&&

.AVIATION /11Z WEDNESDAY THROUGH SUNDAY/...
Showers and a few rumbles of thunder are approaching the western
airfields at sunrise. These showers will spread eastward and
overspread most of the Susquehanna Valley by late morning or
early afternoon. Conditions will lower some, but given the
amount of dry air at low levels and time of day, expect most
areas to be MVFR or higher.

The first batch of showers may taper to nothing for a brief
time before more showers arrive later in the afternoon and
evening. There could be a thunderstorm as well, mainly across
the far west, closer to the warm sector.

Southeast flow develops tonight, which will support low ceilings
and visibility in eastern and central PA overnight. IFR
restrictions are most probable at IPT, MDT, and LNS with MVFR
most likely farther west.

Outlook...

Thu...Post-fropa wrly flow. MVFR cigs sct SHRA NW, VFR SE.

Fri...CFROPA. Occnl dips to IFR.

Sat-Sun...No sig wx.

&&

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

&&

$$

SYNOPSIS...Steinbugl
NEAR TERM...Steinbugl
SHORT TERM...Fitzgerald/Steinbugl
LONG TERM...Fitzgerald/Bauco
AVIATION...Banghoff