Severe Thunderstorm Warning 65, NWS State College, PA

Area Forecast Discussion
National Weather Service State College PA
325 PM EDT Fri May 16 2025

.SYNOPSIS...
* Periods of rain and thunderstorms through Saturday with some
  potential for localized damaging winds and flooding downpours
* Breezy, cooler, and much drier (less humid) end to the weekend
  with rain-free conditions into early next week

&&

.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
Weak thunderstorms along an old boundary are moving toward the
backyard. Other SHRA/TSRA are expected to pop up pretty much
anywhere around the CWA, mainly S of I-80. Curved jet rolling
over the mini upper ridge overhead has it's core of fastest
winds to our west. The best forcing/lift will be generated over
the srn tier by 20Z, and should help to continue to make storms
as it lifts N/NE across the CWA between 20Z-01Z. SPC has put out
an MCD which matches up with the going SLGT risk area (60%
watch issuance prob). Good heating after earlier storms/rain has
left us very moist with mid- summer 65-69F dewpoints
widespread. Despite low QPF numbers for this evening from, all
mdls/guid, the wet ground and moist atmos could produce brief
heavy rain.

After the initial burst of SHRA/TSRA, there will be a lull in
precip until well after midnight. An MCS is progged by many guid
members to slide right along and S of the MD border between
06-09Z. There could be some TSRA sneak N and we'll keep 30 PoPs
in the S. May be reducing the PoPs further than current numbers
over a large portion of the CWA overnight. But, collab with
neighbors will lead to the ultimate numbers. A few SHRA/TSRA
could also linger or redevelop in the nrn tier before sunrise.

&&

.SHORT TERM /6 AM SATURDAY MORNING THROUGH SATURDAY NIGHT/...
The CFRONT moving in from the Upper Great Lakes will not arrive
until ~15Z over the NW, and move steadily through the CWA on Sat.
The amount of recovery we get from early morning stability will be
key to the potential severity of the storms which could form in
the warm sector and along the front. SPC has just dropped the
SLGT risk from the E, and most of the CWA is in the MRGL risk
for svr wx on Sat. Still some uncertainty with that, though, so
we wouldn't be surprised to have that SLGT risk walked westward
again at some point.

Drying will ensue post-fropa, allowing the dewpoints and temps to
dip Sat night.

&&

.LONG TERM /SUNDAY THROUGH FRIDAY/...
Departing and potent mid and upper level closed upper low over
the Upper St.Lawrence Valley to start the period will have one
last spoke of vorticity/cool air aloft rotating through its
Southwest quadrant. This feature will help to bring the
cloudiest and "possibly" the coolest "daytime" conditions of the
next week - with to plenty of thick strato cu and even some
occasional sprinkles and scattered, ground-wetting showers.
Accentuating the chill will be a gusty WNW wind in the mid 20s
to low 30s (MPH) range.

As is typical with this type of pattern, more numerous lake
enhanced rain showers will occur across the NW Mtns where there
is a fairly high (60-70 percent) probability for at least
several hundredths of an inch of rain. the Scent Mtns should see
some breaks of sun and nothing more than a few sprinkles on
Sunday.

GEFS 850T anomaly shows a slight downward T trend for Monday
into Tuesday with neutral/warming and ridging aloft. This will
help day time temps rebound greatly while allowing for mainly
clear and chilly conditions Monday night with a potential for
frost over central and northern PA with PWAT values dipping to
well below normal - or 0.3 to 0.4 of an inch.

The mid to late week period is highlighted by another fairly
sharp trough axis moving across the region on Thursday, preceded
and accompanied by numerous showers and a chance for afternoon
TSRA. The max in rainfall/TSRA risk will be Wednesday as PWATS
rebound to near or slightly above one inch across at least the
Southern Half of PA.

Notably cooler air returns for Thursday and Friday as both the
GFS and EC are in fairly good agreement on yet another closed
low moving over or just to the north of PA (though the EC is
about 12 hours or so slower with this feature).

Thursday and Friday could be quite similar to Sunday of this
weekend (which is mainly cloudy and chilly) with sprinkles and
Northern/Western Mtn lake enhanced showers.

&&

.AVIATION /20Z FRIDAY THROUGH WEDNESDAY/...
VFR now, but sct TSRA popping up along old outflow W of UNV.
Additional, sct, SHRA/TSRA will be popping up as heating peaks.
The best forcing will be with a wave moving up from the SW,
driving convection SW-NE over Central PA between 20Z-01Z.
Current SHRA/TSRA in WV seem to be the feature that will be best
to use for timing. Have stayed close to LAMP guidance for
CIGs/VISBY after 01Z. Most models keep 85% of convection later
tonight (05-10Z) confined south of the MD border. But, some
storms may drift up to the Turnpike. Left mentions of storms
later tonight out of the srn terminal. JST would be the only
place I might have mentioned it at this point. Wind does get
gusty in the morning as the gradient tightens in the warm sector
ahead of a cold front. That front should move through during
the daylight hours. Stronger storms are possible for the ern
terminals (IPT/MDT/LNS) in the aftn. Drying should occur in the
late aftn for the western terminals behind the cfront.

Outlook...

Sun...Mainly VFR. Isold SHRA BFD.

Mon-Tue...VFR.

Tues PM-Wed...Ocnl SHRA/TSRA.

&&

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

&&

SYNOPSIS...Dangelo
NEAR TERM...Dangelo
SHORT TERM...Dangelo
LONG TERM...Lambert
AVIATION...Dangelo

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Preliminary Local Storm Report
National Weather Service State College PA
553 PM EDT Fri May 16 2025

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0542 PM     Tstm Wnd Dmg     2 ESE Emigsville        39.99N 76.70W
05/16/2025                   York               PA   Utility Company

            Trees down on wires.

&&

DNM

Preliminary Local Storm Report
National Weather Service State College PA
558 PM EDT Fri May 16 2025

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0552 PM     Tstm Wnd Dmg     3 S New Cumberland      40.19N 76.87W
05/16/2025                   York               PA   911 Call Center

            Trees and wires down on Steigerwalt Hollow
            Road.

&&

ART

Preliminary Local Storm Report
National Weather Service State College PA
603 PM EDT Fri May 16 2025

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0530 PM     Tstm Wnd Dmg     3 ENE Hanover           39.83N 76.93W
05/16/2025                   York               PA   911 Call Center

            Trees and wires down across Jacobs Mill
            Road.

&&

ART

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