A cold front was responsible for afternoon and evening thunderstorms. A few of these thunderstorms caused flash flooding.
Every event with a place to put it. Tap one for its entry below.
Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS PHI wrote it up.
A cold front was responsible for afternoon and evening thunderstorms. A few of these thunderstorms caused flash flooding.
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Philadelphia/Mount Holly wrote its last area forecast discussion before the first event at Aug 17, 7:31 PM EST, 1 hour 52 minutes earlier.
Area Forecast Discussion
National Weather Service Mount Holly NJ
831 PM EDT Sun Aug 17 2025
.SYNOPSIS...
A cold front will pass through the region tonight, becoming
stationary over southern Virginia on Monday. High pressure
builds in from the north through the middle to end of next week
as Hurricane Erin passes by well offshore.
&&
.NEAR TERM /THROUGH MONDAY/...
As of 7:15pm...Scattered convection is ongoing across much of
the area this evening. Several outflow boundaries from earlier
storms are found over much of the area, which continue to spark
up some additional showers and storms. A more organized area of
convection is moving in from the west over extreme southern PA
and Maryland which is expected to move into southern NJ and the
Delmarva over the next few hours. Behind this, the cold front
will be advancing in from the north, shunting any residual
shower and storm activity to the south of our area.
Convection should come to an end by midnight as the frontal
boundary moves from north to south across the area. This will
cause winds to shift from SW to N/NE after midnight with a low
stratus deck likely setting up. Lows by Monday morning look to
range from around 60 north to around 70 near the urban corridor,
most of Delmarva, and coastal areas.
Monday looks to be sharply cooler compared to Sunday as
northeast flow and low status persist in the wake of the cold
front. The cold front will stall across southern Virginia and
since it will remain in our proximity, there may be some
lingering spotty showers around. Otherwise, the big story will
the cooler temperatures and lower dew points. In fact, much of
the area looks to see highs not getting out of the 70s under
mostly cloudy skies. It'll also be quite windy where winds may
gust occasionally up to 20-30 mph before tapering off later in
the day.
&&
.SHORT TERM /MONDAY NIGHT THROUGH TUESDAY NIGHT/...
A cooler airmass will be moving into the region in the form of a
high pressure system. This will lead to onshore flow and a
continuation of the stark change in overnight lows and day time
highs with lows Monday night and Tuesday night expected in the
low to mid 60s and daytime highs Tuesday in the low to mid 70s.
A stalled frontal boundary lingering just south of the area
should lead to some isolated shower potential but not expecting
a washout by any means.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
The stalled frontal boundary will continue to linger nearby
Wednesday and as some shortwave energy moves in from the west,
this will bring another chance for showers and possibly a few
embedded thunderstorms. Temperatures will remain on the cool
side of climo.
The highest impacts in the extended will be from the TC Erin.
The current forecast keeps the storm offshore, however the
prolonged period of onshore flow and high period swells will
likely cause high surf, dangerous rip currents, the potential
for beach erosion, and coastal flooding through the week.
Please refer to the National Hurricane Center for more details
and stay tuned to the local forecast.
The end of the week should feature benign sensible weather
conditions as high pressure should bring fair and dry weather
and seasonable temperatures. More unsettled conditions may
return Sunday.
&&
.AVIATION /01Z MONDAY THROUGH FRIDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.
Tonight...VFR conditions early, followed by MVFR conditions
later in night (generally after 08Z) as a low stratus cloud deck
moves into the region. Scattered showers and thunderstorms will
linger through about 03Z, before tapering off. Convection
remains widely scattered, so opted to only mention VCSH in TAFs
for now as confidence is not high enough. Southwest winds around
5-10 kt will gradually veer to northwest and eventually
northeast while increasing to 10-15 G 20 kt overnight. Moderate
confidence overall, but lower confidence with regards to timing.
Monday...MVFR ceilings are likely to prevail at all terminals
for much of the day as low stratus deck remains. Skies may begin
to scatter out late in the day near KRDG/KABE. A slight chance
of rain showers near KACY/KMIV, otherwise dry conditions.
East-northeast winds around 10-15 kt with gusts up to 20-25 kt
possible.
Outlook...
Monday Night through Wednesday...Mainly VFR with periods of
sub- VFR conditions possible from showers and thunderstorms.
Thursday and Friday...VFR.
&&
.MARINE...
Small Craft Advisories have been issued for all Atlantic Coastal
waters and now including the Delaware Bay. These advisories
begin as early as 2 AM Monday for northern waters and as late as
7 AM for southern waters.
South-southwest winds around 15-20 kt will persist through
midnight, before a cold front sweeps across the waters. This
front will cause winds to sharply become north-northeasterly
around 20-25 kt with gusts up to 30 kt through Monday. Seas
around 3-4 feet tonight will build to 4-8 feet on Monday.
Outlook...
Monday night through Friday...SCA conditions continue due to
the approach of what is currently Hurricane Erin. Elevated winds
and seas develop Tuesday and will last into at least Friday.
Seas 5-7 feet Tuesday build as high as 8-14 feet by Thursday.
Rip currents...
For Monday, northeasterly wind around 20 mph. Breaking wave
heights generally 2-3 feet. Increasing long period swells
propagating from Hurricane Erin are expected to begin arriving.
Given these factors, have maintained the HIGH risk for the
development of dangerous rip currents at all area beaches.
For Tuesday, east-northeasterly wind 10-15 mph. Breaking wave
heights 3-6 feet. Long period southeasterly swells (potentially
near 20 seconds) associated with Hurricane Erin will continue.
There is a HIGH risk for the development of dangerous rip
currents at all area beaches.
A Rip Current Risk Statement will be in effect both Monday and
Tuesday, and will likely need to be continued further into the
week.
For specific beach forecasts, visit weather.gov/beach/phi
&&
.PHI WATCHES/WARNINGS/ADVISORIES...
PA...None.
NJ...High Risk for Rip Currents from 8 AM EDT Monday through Tuesday
evening for NJZ014-024>026.
DE...High Risk for Rip Currents from 8 AM EDT Monday through Tuesday
evening for DEZ004.
MD...None.
MARINE...Small Craft Advisory from 7 AM to 10 PM EDT Monday for ANZ430-
431.
Small Craft Advisory from 2 AM Monday to 6 AM EDT Friday for
ANZ450-451.
Small Craft Advisory from 4 AM Monday to 6 AM EDT Friday for
ANZ452-453.
Small Craft Advisory from 7 AM Monday to 6 AM EDT Friday for
ANZ454-455.
&&
SYNOPSIS...Franklin
NEAR TERM...DeSilva/Fitzsimmons/Franklin
SHORT TERM...MJL
LONG TERM...MJL
AVIATION...DeSilva/Franklin/MJL
MARINE...Cooper/DeSilva/Franklin/MJLPreliminary Local Storm Report
National Weather Service Mount Holly NJ
906 PM EDT Sun Aug 17 2025
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0850 PM Rain 1 SSE Rancocas 39.99N 74.86W
08/17/2025 M2.52 Inch Burlington NJ Cocorahs
2.52 inches of rain in one hour.
&&
GorsePreliminary Local Storm Report
National Weather Service Mount Holly NJ
929 PM EDT Sun Aug 17 2025
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0918 PM Rain 1 ESE Lumberton Twp 39.96N 74.79W
08/17/2025 M2.99 Inch Burlington NJ Mesonet
Mesonet station GW2630 Lumberton.
&&
GorsePreliminary Local Storm Report
National Weather Service Mount Holly NJ
934 PM EDT Sun Aug 17 2025
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0930 PM Rain Lumberton Twp 39.96N 74.81W
08/17/2025 M3.74 Inch Burlington NJ Public
Private weather station.
&&
GorsePreliminary Local Storm Report
National Weather Service Mount Holly NJ
1002 PM EDT Sun Aug 17 2025
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
1000 PM Rain Lumberton Twp 39.96N 74.81W
08/17/2025 M3.88 Inch Burlington NJ Public
Personal weather station.
&&
GorsePreliminary Local Storm Report
National Weather Service Mount Holly NJ
1003 PM EDT Sun Aug 17 2025
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
1000 PM Rain Mount Holly WFO 40.01N 74.82W
08/17/2025 M2.19 Inch Burlington NJ Mesonet
Mesonet station EW3827 Westampton.
1000 PM Rain 1 E Willow Grove 40.14N 75.11W
08/17/2025 M2.14 Inch Montgomery PA Mesonet
Mesonet station EW1527 Willow Grove.
1000 PM Rain 1 NNE Rancocas 40.02N 74.86W
08/17/2025 M1.97 Inch Burlington NJ Mesonet
Mesonet station FW5135 Willingboro.
0952 PM Rain 1 NNW Rockledge 40.10N 75.10W
08/17/2025 M1.80 Inch Montgomery PA Mesonet
Mesonet station FW0421 Willow Grove.
&&
GorsePreliminary Local Storm Report
National Weather Service Mount Holly NJ
1010 PM EDT Sun Aug 17 2025
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0950 PM Rain 1 SSE Rancocas 39.99N 74.86W
08/17/2025 M3.32 Inch Burlington NJ Cocorahs
Updated report from 1 SSE Rancocas. 2.52
inches of rain occurred from about 7:50 PM
to 8:50 PM.
&&
GorseThe Philadelphia radar (KDIX), 56 km away, was scanning. The volume nearest the first event began at 02:20 UTC.
1 flash flood. Local standard time, as filed.
The Pennypack Creek rapidly exceeded minor flood stage.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Pennsylvania in 2025Every state in 2025This day in weather historyWarnings in Pennsylvania, August 2025
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 1289595.