-- Discussion containing changed information from previous version are highlighted. --
250
FXUS61 KCTP 290255
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
1055 PM EDT Tue May 28 2024

.SYNOPSIS...
Low pressure moving through Wednesday will push a cold front
through and generate numerous showers and thunderstorms. It then
turns dry to close out the month of May with above average
temperatures returning into the first week of June. The chance
for showers returns on Sunday.

&&

.NEAR TERM /THROUGH WEDNESDAY/...
Added the mention of fog to the central valleys where rain fell
earlier and wind is going light/calm. The nrn tier may not clear
out enough/long-enough to allow much fog to form up there.
Dipped temps in the usually cold/rural spots a deg or two.

Prev...
Showers are rapidly diminishing in coverage and intensity as we
lose the heat of the day. Still an area of convergence along rte
22 from PIT to AOO. Also a good short wave trough helping
convection roll down across the Niagara Escarpment and wrn NY.
All these should be weakening over the next 1-2 hrs, too. Tweaks
mainly to sky and PoPs for the next few hours.

Prev...
Lead shortwave aloft and sfc trough embedded within broad
cyclonic flow over the Northeast U.S. will combine with strong
diurnal heating to expand the current area of numerous showers
drifting SE from the Northern Mtns this midday hour.

Max POPs through the mid-late afternoon hours are over the NW
half of the CWA and trend lower (to virtually nothing) over the
the Lower Susquehanna Valley through 21-22Z.

However, by 22-23Z, the primary belt of showers will sink south
of Interstate 80 and focused about 30NM north and south of a
like from KAOO to KSEG and KAVP.

Otherwise, look for a mix of clouds and sun today with a
westerly breeze gusting between 25-30 mph. Highs will range
from 65-80F from northwest to southeast.

Showers will gradually diminish through the evening with mainly
dry conditions expected tonight. Focus will shift to more
potent upstream disturbance rotating into the Upper Ohio Valley
by 12Z Wed. Min temps will be in the low to mid 50s or near to
slightly above (+5F) late May climo.

&&

.SHORT TERM /WEDNESDAY NIGHT/...
Short-range model consensus continues to signal the greatest
coverage of showers and t-storms will be Wednesday afternoon
into the the evening in association with a stronger shortwave
and possibly a meso-b scale weak sfc low rotating along the
PA/MD line.

These features will combine with steeper lapse rates/more
instability (thanks to abnormally cool 700mb temps with MU CAPE
values in the 600-900 J/KG range) to promote numerous
showers/t-storms especially over Central and Southern PA in the
afternoon and early evening.

The diurnally enhanced convection will fade/shift to the east
Wednesday night. Final shortwave digs southeastward from the
lower Great Lakes with 500mb heights bottoming out on Thursday.

Should skies clear out sufficiently and the wind become light
and variable late Wed night/early Thu morning, there`s a chance
for patchy light frost in the coldest high valleys near and to
the east of KBFD.

A couple of showers are possible Thursday afternoon beneath the
upper trough axis, but lower pwat air being directed into the
region via NNW low level flow should keep most places dry.
Seasonably strong high pressure dome migrates eastward Thursday
night into early Friday morning which will support the drying
trend through late week or the end of May. Temperatures will be
seasonably cool for this time of year with the largest
departures from climo (-5 to 10F) Thursday-Thursday night. Min
temps could dip into the upper 30s in the NW mtns.

&&

.LONG TERM /THURSDAY THROUGH TUESDAY/...
-- Changed Discussion --
Medium range models remain are in good agreement for an
extended stretch of dry weather extending from Thursday through
Sunday morning. Temperatures under a large dome of Canadian high
pressure will start out below normal, with quite pleasant
conditions and low humidity on Thursday and Friday, before
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.
-- End Changed Discussion --

&&

.AVIATION /03Z WEDNESDAY THROUGH SUNDAY/...
-- Changed Discussion --
Showers and potentially a thunderstorm or two will continue for
a few more hours before dissipating relatively quickly after
sunset. VFR conditions are expected to continue across the
southern half of Central PA, while restrictions are expected
across the north as fog and low clouds develop. The best chance
for IFR/LIFR conditions will be at BFD, though UNV and IPT will
likely see a period of MVFR conditions from around 06Z through
sunrise. Would not be surprised to see a period of low ceilings
develop at JST as well with upslope flow developing overnight,
but with the HREF only showing a 20-30% chance of MVFR ceilings
developing, decided to keep them VFR all night with a mention of
scattered clouds below 1000 feet. Conditions will improve to
VFR area-wide by late morning.

An approaching shortwave and a weak area of low pressure will
move into the region during the late morning/early afternoon
tomorrow and will bring renewed chances for rainfall. The rain
will begin moving in from the west around 15Z and will spread
eastward into the afternoon. With 500-1000 J/kg of MUCAPE,
thunder appears likely. Decided to hold off on mentioning
thunder in the TAFs for now until there is more confidence on
the most likely timeframe for thunderstorms at each site. Brief
visibility restrictions are possible in any heavier
thunderstorms, but ceilings likely remain VFR across the area
through 00Z Thursday.

Outlook...

Wed Night-Sat...Predominantly VFR.

Sun...Showers and thunderstorms possible.
-- End Changed Discussion --

&&

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

&&

$$

SYNOPSIS...Lambert
NEAR TERM...Lambert/Dangelo
SHORT TERM...Lambert
LONG TERM...DeVoir/Bauco
AVIATION...Bauco