-- Discussion containing changed information from previous version are highlighted. --
451
FXUS61 KCTP 211518
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
1118 AM EDT Tue May 21 2024

.SYNOPSIS...
*Surge of summerlike warmth and humidity through midweek
*Strong to severe t-storms possible Wednesday afternoon
*Seasonably warm & unsettled Thursday through Memorial Day

&&

.NEAR TERM /THROUGH TONIGHT/...
Patchy fog and low stratus in the southern Alleghenies and
middle to lower Susquehanna Valley will dissipate within the
next hour or two as temps warm quickly into the mid 70s by
10AM/15Z.

Expect a mix of clouds and sun through the rest of today with
very warm temperatures for this time of year. Fcst highs will be
a few degrees warmer vs. yesterday reaching the low to mid 80s
or ~10-15F above late May climo/making it feel like Summertime.
We can`t rule out a stray shower/t-storm with the heating of
the day primarily over the western and northern higher terrain
-- however most locations will stay dry.

Mainly clear to partly cloudy and comfortable tonight with
patchy valley fog and min temps in the upper 50s to low 60s.

&&

.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
Wednesday will be the warmest day of the week with summerlike to
near record max temps forecast in the mid to upper 80s. See
the climate section of the AFD to find out which sites have the
best shot at tying or setting a new daily record high for 5/22.

The surge in summerlike warmth will combine with dewpoints in
the low/mid 60s to support moderate destablization Wednesday
afternoon with MLCAPE values progged in the 1000-1500 J/kg
range. While 0-6km shear values are fcst to remain <30kts over
most of CPA, the instability/steep lapse rates may be sufficient
to support isolated strong to locally damaging wind gusts with
t-storms into the early evening. SPC has upgraded the northwest
1/2 of the CWA to a Slight risk or severe t-storm risk level 2
out of 5. The CAMs show t-storm clusters developing ahead of an
eastward advancing cold front/near a leading pre frontal trough
and moving west to east across the area from around midday
through the late evening. Remnant MCVs associated with Day 1/Tue
convection may also provide additional forcing for ascent as
they propagate into the Lower Great Lakes within southwesterly
flow aloft. More showers and t-storms are likely on Thursday as
the primary cold front slowly moves through the area and settles
near the MD line Thursday night. The focus for stronger storms
shifts into far southeastern PA on Thursday afternoon with the
D3 MRGL SWO just clipping Lancaster County.

High temps will cool off a bit over most of CPA on Thursday into
the mid 70s to lower 80s, but remain above climo for this time
of year. Low temps Thursday night/AM Friday in the 55-65F range
will not be as warm/humid as Wednesday night.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
Temperatures should remain on the mild side through the end of
the week. The cold front will come through on Thursday and then
stall just south of PA on Friday. The proximity of the stalled
front will result in a continued chance of scattered showers and
t-storms for at least southern PA.

There remains some uncertainty in the forecast heading into the
Memorial Day weekend, but it appears that Central PA`s weather
could remain mild but showery.

&&

.AVIATION /15Z TUESDAY THROUGH SATURDAY/...
-- Changed Discussion --
Minor update late this morning. Fog is gone, and just some
high clouds. The airmass is not real moist, thus CU and showers
will be very limited. Thus backed off on timing of showers
at BFD by a few hours.

Earlier discussion below.

Patchy fog is present across some of the Lower Susquehanna
Valley for the early morning hours today. These visibility
restrictions should rise quickly after 8 AM.

VFR and calm winds will prevail for most of Tuesday after the
early morning fog lifts out of the region. There are a few
scattered showers possible for the NW PA, but their coverage
remains low and confidence is too low to include them in the BFD
TAF other than a mention of VCSH. The next chance for
significant convection will be Wednesday night with a slight
risk for severe weather in place across NW PA.

Outlook...

Wed...Scattered t-storms, stronger storms NW.

Thu...Chance of t-storms.

Fri-Sat...Mainly VFR, slight chance of showers.
-- End Changed Discussion --

&&

.CLIMATE...
Daily record maximum temperatures for 5/22:

Harrisburg96/1941
Williamsport95/1941
Altoona88/2013
Bradford84/2013
State College89/1975

&&

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

&&

$$

SYNOPSIS...Steinbugl
NEAR TERM...Steinbugl
SHORT TERM...Steinbugl
LONG TERM...Evanego/Bowen
AVIATION...Martin/Bowen
CLIMATE...Steinbugl