305
FXUS61 KCTP 290558
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
158 AM EDT Wed May 29 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 TODAY/...
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 /TONIGHT THROUGH 6 PM THURSDAY/...
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 NIGHT THROUGH TUESDAY/...
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.

&&

.AVIATION /06Z WEDNESDAY THROUGH SUNDAY/...
VFR conds across SE PA are expected overnight with high (> 80%)
confidence while moderate (50-60%) confidence in VFR conds
continuing at AOO/IPT throughout the overnight period given the
low-level dry air at IPT as of 05Z Wednesday. There is higher
confidence on lower cigs forming at BFD/JST overnight with MVFR
cigs likely at both airfields after 09Z Wednesday. Guidance has
outlined some signals for a fairly rapid drop towards IFR at
JST/BFD in the 09Z-10Z Wednesday timeframe with HREF probs in
both MVFR/IFR cigs increasing significantly at JST in recent
runs. This seems plausible given lighter winds and clear skies
persisting this late into the evening, so have timed out best
possible timing for these restrictions. After sunrise, both
airfields are expected to lift towards high-end MVFR to low-end
VFR thresholds in the 13Z-15Z Wednesday timeframe.

Guidance has trended later with the approaching shortwave early
afternoon tomorrow with higher coverage of SHRA expected
throughout the day Wednesday. Rain is currently expected to
begin moving in from the west around 16Z and continue spreading
eastward into the afternoon. Brief visibility restrictions are
possible in any heavier showers and storms (see below), but
ceilings likely remain above VFR thresholds through 03Z. Sub-VFR
conds are possible across western airfields after 03Z Thursday.

As stated in previous discussions, elevated CAPE indicates
higher chances of TSRA as these showers progress across the area
today. This package outlines a fair window where TSRA is
possible at all airfields. In the next TAF package, expect to
tighten timing up where increasing confidence allows. At this
time, guidance does outline best chances of TSRA across the west
(BFD/JST/AOO) in the 20Z-22Z Wednesday timeframe with these
chances continuing towards eastern airfields (IPT/MDT/LNS) in
the 22Z-24Z Wednesday timeframe.

Outlook...

Wed Night-Sat...Predominantly VFR.

Sun...Showers and thunderstorms possible.

&&

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

&&

$$

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