Severe Thunderstorm Warning 236, NWS State College, PA

Area Forecast Discussion
National Weather Service State College PA
1156 AM EDT Fri Aug 7 2026

.WHAT HAS CHANGED...
* Raising POPS and basin avg QPF by a few to several tenths of
  an inch across the Northwest this morning/early afternoon and
  across the SE half of the CWA for this afternoon.

&&

.KEY MESSAGES...
1) Periods of showers/scattered thunderstorms through Saturday
will bring localized flash flooding risk across central
Pennsylvania. Strong-to-severe storms also possible this
afternoon/evening.

2) Very warm temperatures and humid conditions will lead to heat
index values approaching 100 degrees across portions of the
Lower Susquehanna Valley today.

&&

.DISCUSSION...
KEY MESSAGE 1: Periods of showers/scattered thunderstorms
through Saturday will bring localized flash flooding risk across
central Pennsylvania. Strong-to-severe storms also possible
this afternoon/evening.

Weak llvl boundaries and areas of signif differential heating
gradient and topographic effects will be the weather influencers
for the midday through early evening hours today. Larger scale
forcing associated with the favorable right entrance region of
a 50-60 kt upper level jet core will move gradually east across
the CWA this afternoon and evening and help to realize the
hefty 2000-3500 j/kg CAPE in the form of localized strong
pulse/multicell TSRA updrafts. Bands of significantly lower 1-6
hour Flash Flood Guidance values across portions of the Susq
Valley and Scent Mtns will have to be monitored closely this
afternoon as convection ramps up/moves east and feeds off the
best instability across this same area.

Weakening convection across the NW third of the CWA and extensive
cloud cover was leading to a notable min in instability with SB
CAPE of 500-1000 J/KG, similar to the setup we saw Thursday
afternoon/evening.

Previous...

Activity on Thursday was largely driven by the terrain in
combination with a very moist airmass. Overall a similar
situation today and Saturday. Location of the more active
weather on Saturday may be a bit further to the east and south.
That is still a ways out.

For the overnight hours into Friday morning, the main concern
aside from an isolated shower will be the potential for fog/low
stratus development with mainly clear skies and calm winds.

More information below.

This concern will be highest in areas that received heavy
rainfall across southern Pennsylvania on Thursday. Updated fog
forecast does outline this potential with valley fog expected
across the northern half of central Pennsylvania. Any fog
formation likely mixes out quickly after sunrise and is out by
9AM EDT.

First glance at the first couple of hours of 00Z 8/7 HREF
ensemble guidance outlines an uptick in shower activity across
northern Ohio overnight compared to previous runs. Thus, have
increased PoPs slightly earlier across NW PA closer to sunrise
compared to previous forecast. Increasing humidity throughout
the day with ample instability (~1000-2000 J/kg across N/W PA
and 2000+ J/kg across S/E PA) will likely allow for slightly
more widespread coverage with more height falls observed in
recent model guidance compared to this afternoon and evening.
In terms of a severe threat, expect scattered thunderstorms to
develop with potentially a slight uptick in coverage compared to
this afternoon. Isolated instances of strong-to-damaging winds
appear to be the main hazard with these, mainly in the form of
wet microbursts given the instability, moisture, and lift
(trough approaching the area) in play.

The overly moist air mass, with PWATs exceeding the 90th
percentile across all of central Pennsylvania, will brings
another round of flash flooding concerns on Friday and Saturday,
mainly during the afternoon/evening hours. This flooding threat
could be minimized by more progressive storm motions; however,
given the amount of moisture, any shower/storm will likely bring
efficient rainfall to the region and any location (especially
urban and poor drainage locations) that receive multiple rounds
of heavy rainfall could experience localized flash flooding.
Recent HREF PMMs does paint a corridor 2-3" rainfall amounts
along the Pennsylvania Turnpike Friday afternoon/evening, which
tracks with the ample moisture available. Do want to highlight
that while this signal exists, location of this corridor remains
the main point of uncertainty at this time so remain weather
aware and have multiple ways to receive warnings tomorrow
afternoon/evening. Heavy rain signal on Saturday is more muted;
however, if this heavier corridor of rain plays out as
predicted, some locations could need very little rainfall for
additional flooding concerns on Saturday.

   ------------------------------------------------------

KEY MESSAGE 2: Very warm temperatures and humid conditions will
lead to heat index values approaching 100 degrees across
portions of the Lower Susquehanna Valley today.

Current grids only show a few grid points getting close.
Also temperatures being push back down by showers and
storms, temperatures may not stay up in that range for
very long anyway.

More information below.

Increasing heat and humidity throughout the afternoon hours
ahead of the aforementioned showers/storms will lead to another
hot day across portions of the Lower Susquehanna Valley and
surrounding locations. Recent model guidance does indicate a
slight decrease in temperatures tomorrow with increasing cloud
cover during the late morning/early afternoon hours across the
region which could limit peak heating slightly. That being said,
moisture will be plentiful with dew points expected to reach
into the mid-70s during the afternoon hours ahead of forecast
precipitation. Recent HREF guidance of heat index values
exceeding 100F appear to be more confined to the south and east
of Lancaster County. Highest probabilities max out around
~30-40% for far southern Lancaster County. For reference,
similar guidance was highlight probabilities closer to ~60-70%
for similar locations this afternoon/evening. Given the
uncertainty, have decided to let the upcoming midnight shift
handle heat headlines for Friday to get another run of HREF/NBM
model guidance to assist in this decision. Whether or not a heat
headline gets posted, hot and humid conditions are expected for
the Lower Susquehanna Valley tomorrow before a slight decrease
in heat/humidity for the upcoming weekend.

&&

.AVIATION /15Z FRIDAY THROUGH TUESDAY/...
For the 18Z TAF package, main changes will be to adjust the
timing and duration of convection and the onset of lower
cigs/vsbys in fog later tonight/early Saturday.

Included PROB30s with TSRA with visibility restrictions for
scattered afternoon thunderstorms at the TAF sites. Similar to
Thursday, the storms will be hit or miss, but high PWATs and
heavy downpours mean storms may be capable of brief IFR
visibility restrictions should they cross paths with a terminal.

Outlook...

Sat...Pockets of fog in the morning. Scattered showers/isolated
t-storms with heavy downpours and localized restrictions.

Sun...Mostly dry, some potential for isolated showers across far
W PA. Restrictions possible.

Mon-Tue...Scattered showers/storms. Restrictions possible.

&&

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

&&

WHAT HAS CHANGED...Lambert/Martin/Beaty
KEY MESSAGES...Lambert/Martin/Beaty
DISCUSSION...Lambert/Martin/Beaty
AVIATION...Lambert/Martin/Lambrech

Hazardous Weather Outlook
National Weather Service State College PA
122 PM EDT Fri Aug 7 2026

PAZ004>006-010>012-017>019-024>028-033>035-037-041-042-045-046-
049>053-081730-
Warren-McKean-Potter-Elk-Cameron-Northern Clinton-Clearfield-
Northern Centre-Southern Centre-Cambria-Blair-Huntingdon-Mifflin-
Juniata-Somerset-Bedford-Fulton-Tioga-Northern Lycoming-Sullivan-
Southern Clinton-Southern Lycoming-Union-Snyder-Montour-
Northumberland-Columbia-
122 PM EDT Fri Aug 7 2026

This Hazardous Weather Outlook is for central Pennsylvania.

.DAY ONE...This afternoon and tonight.

Heavy rain is possible from scattered thunderstorms today
which may lead to isolated instances of flash flooding.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday.

Heavy rain is possible from scattered thunderstorms again on
Saturday, which may lead to isolated instances of flash flooding.

.SPOTTER INFORMATION STATEMENT...

Spotters are encouraged to report significant hazardous weather.

PAZ036-056>059-063>066-081730-
Franklin-Perry-Dauphin-Schuylkill-Lebanon-Cumberland-Adams-York-
Lancaster-
122 PM EDT Fri Aug 7 2026

...SEVERE THUNDERSTORM WATCH 540 IN EFFECT UNTIL 9 PM EDT THIS
EVENING...

This Hazardous Weather Outlook is for central Pennsylvania.

.DAY ONE...This afternoon and tonight.

Please listen to NOAA Weather Radio or go to
weather.gov/StateCollege on the internet for more
information about the following hazards.

   Severe Thunderstorm Watch.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday.

No hazardous weather is expected at this time.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not expected at this time.

Preliminary Local Storm Report
National Weather Service State College PA
226 PM EDT Fri Aug 7 2026

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

0206 PM     Tstm Wnd Dmg     2 SSE Carlisle Springs  40.22N 77.16W
08/07/2026                   Cumberland         PA   Trained Spotter

            Power lines down.

&&

JAB

Preliminary Local Storm Report
National Weather Service State College PA
229 PM EDT Fri Aug 7 2026

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

0220 PM     Hail             2 SE Carlisle Springs   40.22N 77.16W
08/07/2026  M0.88 Inch       Cumberland         PA   Public

&&

JAB

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Preliminary Local Storm Report
National Weather Service State College PA
304 PM EDT Fri Aug 7 2026

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

0250 PM     Flash Flood      2 SSE East Petersburg   40.08N 76.34W
08/07/2026                   Lancaster          PA   Fire Dept/Rescue

            Water across roadway near the intersection
            of Flory Mill Road and Commerce Drive in
            Manheim Township.

&&

Preliminary Local Storm Report
National Weather Service State College PA
311 PM EDT Fri Aug 7 2026

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

0307 PM     Flash Flood      3 ENE Mountville        40.05N 76.38W
08/07/2026                   Lancaster          PA   Fire Dept/Rescue

            Water across roadway near the intersection
            of Running Pump Road and Marietta Avenue in
            East Hempfield Township.

&&

Preliminary Local Storm Report
National Weather Service State College PA
314 PM EDT Fri Aug 7 2026

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

0256 PM     Tstm Wnd Dmg     1 W Pottsville          40.68N 76.23W
08/07/2026                   Schuylkill         PA   911 Call Center

            Road closed due to trees over roadway.

&&

JAB