830
FXUS61 KCTP 291137
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
737 AM EDT Wed May 29 2024

.SYNOPSIS...
*Numerous showers/t-storms expected this afternoon->evening
*Drying trend to end May with below normal temperatures
*Seasonal warmup to start June with rain risk increasing into
 early next week

&&

.NEAR TERM /THROUGH TONIGHT/...
Issued SPS for areas of fog/low visibility (1/2-1/4 mile) and
locally hazardous driving conditions early this morning over the
western/northern Alleghenies. Expect fog impacts to end by 9AM.

Shortwave trough will pivot eastward from the upper Ohio
Valley this morning, eventually moving through central PA this
afternoon and evening before exiting the northern Mid Atlantic
coast tonight. 500mb height falls and abnormally cool temps
aloft associated with the aforementioned trough will provide
large scale lift and a period of steep lapse rates within a zone
of modest instability to produce scattered to numerous diurnally
enhanced showers and t-storms. A couple of repeat heavy
downpours could produce local QPF maxes around 1" as they
maneuver over the area into the evening, but the overall lack
of deep moisture (pwats<1") will greatly limit risk of heavy
rain/runoff issues. Max temps will be 5 to 10 degrees below late
May climo across most of CPA this afternoon with highs in the
60-75F range.

Shower activity shifts to the east tonight with patchy fog
possible over the western Alleghenies where skies should clear
out. Seasonably cool night ahead with lows in the 40-55F range.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
Final shortwave trough rotates through CPA on Thursday. A
couple of showers or an isolated PM t-storm are possible
Thursday afternoon beneath the upper trough axis mainly over
southeast PA, but lower pwat air pouring into the region via
NNW low level flow should keep most places dry. Highs will again
be cooler-than-average with fcst max temps in the low 60s/70s.

Seasonably strong high pressure dome migrates eastward from the
OH Valley Thursday night into western PA early Friday morning.
This setup should support one of the coolest nights in a while
with low temps in the mid 30s to upper 40s. Can`t rule out some
frost in the northern tier cold spots which is later than climo
but not that uncommon for the end of May.

Center of 1025mb sfc high is parked right overhead by 12Z
Saturday, ensuring the break in the rain continues into the
first weekend of June. Look for max temps to rebound a bit on
the last day of May with highs staying near/below climo. Another
relatively cool night with lows in the 40-50F range.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
Medium range models remain are in good agreement for an
extended stretch of dry weather through Sunday morning.
Temperatures moderate and humidity creeps up on Saturday and
Sunday. By Sunday, ensembles show upper level flow becoming more
zonal. Multiple shortwaves will move through the region into
the middle of next week bringing chances for showers and storms,
but confidence in the timing of these features is low.

&&

.AVIATION /12Z WEDNESDAY THROUGH SUNDAY/...
(V)LIFR conds across the western highlands (BFD/JST) will
continue for the next hour-two before giving ways to a brief
period of VFR conditions. A period of showers this morning is
likely to get to JST/BFD by 14Z Wednesday with less confidence
further east so have left mentions out at this time. Within
these showers, low-end VFR seems like the most likely options
although cannot rule out a brief drop towards MVFR vsbys/cigs.

Later this afternoon, higher coverage of SHRA is expected to
develop with showers and thunderstorms expected. Brief
visibility restrictions are possible in any heavier showers and
storms (see below) with cigs borderline MVFR/VFR based on recent
model guidance. Elevated CAPE does indicate higher chances of
TSRA as these showers progress across the area today. This TAF
package has tightened up some of the TSRA mention timing
although some uncertainty still exists on exact coverage.

Guidance indicated towards lowered vsbys/cigs at BFD/JST
overnight into Thursday, which seems plausible given increased
low-level moisture, light winds, and potential for some clearing
skies. The main uncertainty at this time remains how quickly
clouds clear out, which could limit fog potential across the
western highlands. Recent guidance does suggest an earlier
clearing time, so have outlined IFR/LIFR restrictions with some
added uncertainty with regards to timing.

Outlook...

Wed Night-Sat...Predominantly VFR.

Sun...Showers and thunderstorms possible.

&&

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

&&

$$

SYNOPSIS...Steinbugl
NEAR TERM...Steinbugl
SHORT TERM...Steinbugl
LONG TERM...DeVoir/Bauco
AVIATION...NPB