734
FXUS61 KCTP 291640
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
1240 PM EDT Wed May 29 2024

.SYNOPSIS...
*Numerous showers/t-storms expected this afternoon and evening
*Drying trend to end May with below normal temperatures
*Temperatures warm to near normal to start June with rain
 chances increasing into early next week

&&

.NEAR TERM /THROUGH TONIGHT/...
Showers and thunderstorms associated with a shortwave trough
over the Upper Ohio Valley are beginning to move in from the
southwest. The showers and thunderstorms will continue to
increase in coverage into the early afternoon. 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 which
will support locally heavy rainfall. Models suggest that an area
of low level convergence will develop somewhere in the central
third of the area this afternoon. Repeating heavy downpours in
this area could produce local QPF maxes around 1-1.5" as they
maneuver over the region into the evening, but the overall lack
of deep moisture (pwats<1") should 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 SATURDAY/...
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 NIGHT THROUGH TUESDAY/...
Models diverge with the amplitude of a shortwave trough moving
through the region late Saturday night into Sunday. This feature
will bring the next chance of showers and thunderstorms to
central PA.

Longer range guidance shows multiple shortwaves moving through
the region into the middle of next week bringing renewed chances
for showers and storms, but confidence in the timing of these
features is low.

&&

.AVIATION /16Z 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/Bauco
SHORT TERM...Steinbugl
LONG TERM...Colbert/Bauco
AVIATION...NPB