915
FXUS61 KCTP 040307
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
1107 PM EDT Fri May 3 2024

.SYNOPSIS...
-Noticeable cool down over the weekend with overcast skies and
 periods of rain
-Remaining unsettled next week with a gradual warming trend

&&

.NEAR TERM /THROUGH SATURDAY/...
Radar loop at 03Z shows dwindling, diurnally-driven convection
over the NW Mtns. The focus for the rest of the night shifts to
the potential of additional showers linked to a mid level vort
max lifting into Southwest PA from the Ohio Valley. Surging
pwats, combined with the arrival of this feature will bring an
increased chance of showers over primarily the southwest portion
of the forecast area late tonight.

An increasingly moist east/southeast flow off of the Atlantic,
combined with upslope flow, will likely yield developing
stratus along the spine of the Appalachians late tonight. Low
temps will be above early May climo and range between 45-55F
from the southwestern Poconos/Coal Region to Warren County.

&&

.SHORT TERM /SATURDAY NIGHT THROUGH SUNDAY NIGHT/...
Model guidance supports developing rain Saturday across Central
PA from south to north ahead of an upper level shortwave
lifting out of the Tennessee Valley. The associated southerly
low level jet and plume of higher pwats overrunning a dome of
cool/stable air across Central PA should result scattered
showers giving way to a steady rain early Sat morning over the
southern tier counties and by late in the day over the northern
tier. The upper level shortwave should begin to lift out of the
area Sunday, resulting in rain tapering off from west to east.
Scattered late day convection appears possible late Sunday over
the Allegheny Plateaus associated with an approaching warm front
over Western PA. Ensemble plumes support rain totals by late
Sunday in the 0.5 to 0.75 inch range for most of the area.

Hires models show CAD pattern firmly entrenched over CPA Saturday,
and therefore we continued to trim max temps vs. NBM, due to
thick cloud cover, easterly flow and arriving rain. We have
blended the cooler NAM surface temps with those of the NBM,
resulting in expected max temps in the mid to low 50s for much
of the area. No risk of thunder on Saturday, so removed from wx
grids and changed character of precip to rain from showers.

Sunday looks to be another cool day for May, due to a persistent
southeast flow off of the Atlantic. However, a slight rebound
is expected over the western counties, due to rain tapering off
the chance for a bit of afternoon brightening.

Subsidence behind the departing shortwave should result in a
mainly rain-free Sunday night. However, a lingering upsloping
southeast flow will likely yield lingering low clouds/patchy
drizzle. Fcst lows Sunday night are +10-15F above climo for
early May in the 50-60F range.

&&

.LONG TERM /MONDAY THROUGH FRIDAY/...
Monday should feature much warmer and drier weather, as high
pressure builds southeast from the Grt Lks behind a Sunday night
cold/occluded front passage. However, the approach of an upper
level shortwave appears likely to produce scattered PM
convection in the vicinity of the stalled front along the Mason
Dixon Line. Highest POPs are placed over the southern tier,
with only slight chc POPs across the north. The return of
sunshine and 850mb temps near 12C translates to expected highs
in the 70s most places.

Upper level ridging over PA indicates warm and generally dry
conditions are likely Tuesday. However, a warm front lifting out
of the Ohio Valley could result in increasing clouds with a PM
shower/tsra, primarily across the southwest counties. The bulk
of medium range guidance supports a very warm Wednesday with
scattered convection, as the area briefly breaks into the warm
sector ahead of a cold front pushing in from the Grt Lks.

Model consensus supports a better chance for a more widespread
rainfall Thursday, associated with a deepening upstream trough
and wave of low pressure riding along the stalled cold front
just south of PA. The surface low and deepest moisture is
progged to shift east of the area by Thursday night. However,
falling heights ahead of the upper trough will likely support
scattered, diurnally-driven convection Friday, along with a
downward trend in temperatures.

&&

.AVIATION /03Z SATURDAY THROUGH WEDNESDAY/...
Scattered SHRA across western PA has largely stayed east of all
airfields in central PA. Some light SHRA passed over JST/AOO
although relatively dry air in the lower-levels made for very
little in the way of rainfall. Some light showers are still in
the vicinity so have outlined VCSH for these airfields for the
next couple of hours. The best chance of SHRA at either airfield
will come in the very near-term (00Z-01Z) although showers
continue to break apart. Chances of TSRA are low (< 30%) and
have kept them out of the TAFs for this cycle, with any TSRA
occurring at BFD/JST. Chances for TSRA after 03Z Saturday drop
even further with the loss of daytime heating.

Chances for low clouds and some fog do remain possible, although
model sounding shave outlined less moisture in the lower-levels
that would promote fog formation. If any fog formation is to
occur, best chances will be across SW PA at JST with lesser
chances at AOO. Southeasterly winds will increase probability
of fog in these locations as well, but with low confidence have
opted to keep fog out of this TAF package.

Light SHRA will continue on Saturday with restrictions expected
at all airfields across central PA. Widespread MVFR conds are
expected by 12Z Saturday with IFR cigs expected across Allegheny
Front airfields (JST/AOO/UNV, lesser IPT) throughout the day on
Saturday.

Outlook...

Sun...Widespread restrictions due to low cigs. SHRA likely with
a chance of TSRA.

Mon-Wed...AM fog/clouds poss. PM -SHRA possible areawide.

&&

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

&&

$$

SYNOPSIS...Steinbugl/Bowen
NEAR TERM...Fitzgerald
SHORT TERM...Fitzgerald/Bowen
LONG TERM...Fitzgerald
AVIATION...NPB