The remnants of Tropical Storm Debby moved through, producing damaging wind gusts with a few severe thunderstorms, and heavy rain.
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.
The remnants of Tropical Storm Debby moved through, producing damaging wind gusts with a few severe thunderstorms, and heavy rain.
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 8, 3:24 PM EST, 1 hour 21 minutes earlier.
Area Forecast Discussion
National Weather Service Mount Holly NJ
424 PM EDT Thu Aug 8 2024
.SYNOPSIS...
A slow moving front will linger near the area through tonight.
The remnants of Tropical Storm Debby will track northward near
our area Friday and Friday night and then merge with this front
which will shift offshore Saturday. High pressure begins to build
in thereafter, holding influence over the region into the beginning
of next week.
&&
.NEAR TERM /THROUGH FRIDAY NIGHT/...
Expect an active next 18 to 24 hours across the region as a
number of different impacts will felt across the region.
The first rounds of rain bands from the remnants of Debby have
moved over the region and we will continue to see periods of
rainfall throughout the next day. The bands have been moving
fast enough thus far to limit flash flooding but the tropical
rainfall is starting to accumulation in portions of DelMarVa and
latest ACARS soundings are verifying that we are solidly in a
tropical environment, with high precipitable water values and
very deep warm cloud layers, so localized flash flooding cant be
ruled out this evening.
Into the overnight hours, low level shear continues to
increase, though we will likely keep a stable boundary layer,
even as the remnant front lifts northward.
On Friday, Debby will lift northward through central PA as it passes
to our west while merging with a frontal boundary. This will cause
it to start to take on more in the way of extra tropical
characteristics, though it will still have plenty of moisture
with it (PWATs 2.5+ inches). With a track farther west, this
means that the very heaviest of the rain should stay to our
west and guidance has kept that trend. Even so widespread
showers will impact the region with a growing concern for
embedded tornados.
We are anticipating a buoyant airmass with a tremendous amount
of low level shear (0-1 km shear 30-40+ knots) and helicity
along with lowering LCLs. This will create favorable conditions
for tornados to develop which is not uncommon for scenarios like
this where a tropical system passes to the west. SPC has
upgraded the area to a SLGT risk with a 5% TOR for areas along
and west of the I95 corridor. Forecast guidance continues to
indicate the potential for discrete cells in the warm section
across DelMarVA, southeastern PA and NJ with spin potential.
As a second round, then a squall line of starts passing through
the area late in the afternoon into the evening from west to
east. There could be tornadic circulations that develop within
this line as well as in earlier cells and clusters that develop
and move through south to north ahead of the line.
The next threat, will be that a strong low level jet between
40-55 kts develops at 850mb. With widespread rain that would be
convective at times, anticipate occasional gusts of 40 to 50 mph
to be possible mixing down. I dont anticipate frequent gusts or
prevailing strong winds, but those occasional gusts when
combined with saturated soils will have the potential to bring
down trees especially in the areas that received heavy rainfall
earlier this week.
The heaviest of the rain is likely to be north/west of the
urban corridor especially getting out into our western zones
from Berk's County northward into the southern Poconos. Places
along and east of the I-95 corridor will still see some heavy
showers though and given how wet it's been recently, this will
mean scattered instances of flash flooding will still be
possible.
For Friday night, Debby lifts north of the area as it moves
into eastern Canada by Saturday. As mentioned above, the final
punch of heavy rain and wind should move through in the evening
with conditions actually starting to clear out overnight. Total
rain amounts for the Friday / Friday night period should
generally be around 2 to 3 inches over N/W area, 1 to 2 inches
near the I-95 corridor and up to around an inch near the coast.
Locally, amounts could be higher than these numbers. And in
addition to the threat of flash flooding, there will be rises on
area creeks, rivers, and streams. This could result in at least
some points seeing river flooding by later Friday night into
Saturday.
&&
.SHORT TERM /SATURDAY THROUGH SATURDAY NIGHT/...
Pleasant weather follows in the wake of all the poor weather
from Thursday and Friday. High pressure ridges in from the west
and remains across the region. Mostly sunny weather is expected
Saturday with some clouds for the far N/W. Much drier air will
be in place and temperatures will be comfortable. Highs will be
in the upper 70s to low 80s with perhaps some mid 80s close to
the shore. West to northwest winds around 10 mph are forecast.
&&
.LONG TERM /SUNDAY THROUGH THURSDAY/...
The long range will feature a cooler, drier pattern than what we've
seen for most of the summer. A broad mean upper trough will dominate
over eastern North America with a few reinforcing short waves moving
through the flow next week. All this means is that the heat and
humidity levels of June & July will take a break from our area. A
prolonged period of normal (or slightly below) temperatures is
expected and rainfall will be sparse.
In fact the period from Sunday thru early Wednesday will not have
any mentionable pops/weather in the grids. High temperatures will be
in the low/mid 80s with lows in the low/mid 60s much of the time.
Cooler temps across the southern Poconos. Humidity levels will be
comfortable too.
&&
.AVIATION /20Z THURSDAY THROUGH TUESDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY and surrounding areas.
Through the rest of today...Expect IFR/MVFR ceilings. Scattered
showers with a few isolated embedded thunderstorms possible,
but coverage is expected to be very limited, so have held off on
including a mention in the TAFs at this time.
Tonight...Likely to have prevailing IFR and MVFR conditions,
primarily due to ceilings. However, there will be increasing
potential for visibility restrictions in heavy rain. As with the
day time period, isolated thunderstorms possible, but coverage
is expected to be very limited if any develop. Southeasterly
winds will be increasing to 10 to 20 kt, with higher gusts
possible.
Outlook...
Friday through Friday night...Periods of IFR/MVFR conditions during
occasional/frequent showers and tstms. Gusty winds Friday/Friday
night. Southerly winds 15 to 20 gusting 30 to 35 knots on
Friday. A strong low level jet will produce areas of turbulence
and low level wind shear during the day Friday
Saturday through Monday...VFR expected. Patchy fog possible during
the overnights.
&&
.MARINE...
Winds and waves will be increasing through the period with winds
generally in the 15-20 kt range and gusts of 25-30kts building
into Friday morning. Gales and high seas will develop Friday
with frequent showers and thunderstorms. Southerly winds 20 to 30
gusting up to 40 knots.
Outlook...
Saturday/Saturday night...Winds/seas diminishing and should go
below SCA levels by Saturday afternoon.
Sunday through Monday...No marine headlines anticipated. Fair
weather.
Rip Currents...
The next two days, persistent and increasing onshore flow will
result in an elevated risk for the formation of dangerous rip
currents. For today, a HIGH risk is expected for the coasts of
Monmouth and Ocean counties, while the coasts of Atlantic, Cape
May, and Sussex (DE) Counties where surf heights will be
slightly lower, a MODERATE risk is expected.
Friday, winds and waves will be even stronger, so a HIGH risk
is expected for the entire area coast line.
For specific beach forecasts, visit weather.gov/beach/phi
&&
.TIDES/COASTAL FLOODING...
Unseasonably strong southerly flow associated with the remnants
of TC Debby will result in elevated water levels with the high
tides on Friday.
Our highest confidence for minor coastal flooding is for the
eastern shore of Maryland along Chesapeake Bay, where forecast
surge values rise to near 2-2.5 feet above MLLW. This is
expected to result in minor coastal flooding, especially in the
more flood prone areas along Chesapeake Bay and adjacent tidal
waterways with the morning and evening high tides. A Coastal
Flood Advisory has been issued to highlight this threat for
these high tides.
Along the Atlantic coasts of New Jersey and Delaware, some
spotty minor flooding is possible in the usual flood prone
spots, although widespread impacts from coastal flooding are
not expected due to the short duration and insignificant surge
values. The exception will be for Barnegat Bay in Ocean County
and Little Assawoman Bay and Rehoboth Bay in Sussex County,
where the strong southerly winds will trap high water from
draining during times of low tide beginning Friday into Friday
night. Generally minor flooding impacts are expected in these
areas, however there is a low chance (20-30% chance) of moderate
flooding impacts. A Coastal Flood Advisory has been issued for
Ocean and Sussex (DE) Counties to highlight this threat for
Friday through Friday night. Additionally, a High Surf Advisory
was issued to highlight to potential for breaking waves up to 8
feet along the coast. This activity may result in sand dune
breaching or beach erosion as well.
Minor coastal flooding remains possible along the upper Delaware
Bay and tidal Delaware River. The persistent strong southeast
to south winds will help push elevated surge values near 1.5- 2
feet into these areas beginning Friday morning through the
evening. This combined with potential heavy rainfall runoff
will probably result in at least some spotty minor coastal
flooding with the afternoon/evening high tide, although
confidence is not quite high enough to warrant an advisory yet.
Will continue to monitor the observations of surge and the
latest guidance to determine if an advisory will be needed in a
future update.
&&
.PHI WATCHES/WARNINGS/ADVISORIES...
PA...Wind Advisory from 11 AM to 8 PM EDT Friday for PAZ054-055-
060>062.
Wind Advisory from 6 AM to 8 PM EDT Friday for PAZ070-071-
101>106.
NJ...Wind Advisory from 6 AM to 11 PM EDT Friday for NJZ013-014-016-
020>027.
Coastal Flood Advisory from 6 AM Friday to 6 AM EDT Saturday
for NJZ020-026.
High Risk for Rip Currents from Friday morning through Friday
evening for NJZ024-025.
High Surf Advisory from 8 AM to 8 PM EDT Friday for NJZ014-
024>026.
Wind Advisory from 11 AM to 8 PM EDT Friday for NJZ001-007.
Wind Advisory from 6 AM to 8 PM EDT Friday for NJZ008>010-012-
015-017>019.
High Risk for Rip Currents through Friday evening for NJZ014-026.
DE...Wind Advisory from 6 AM to 11 PM EDT Friday for DEZ001>004.
Coastal Flood Advisory from 6 AM Friday to 6 AM EDT Saturday
for DEZ003-004.
High Risk for Rip Currents from Friday morning through Friday
evening for DEZ004.
High Surf Advisory from 8 AM to 8 PM EDT Friday for DEZ004.
MD...Wind Advisory from 6 AM to 5 PM EDT Friday for MDZ012-015-019-
020.
Coastal Flood Advisory from 9 AM Friday to 3 AM EDT Saturday
for MDZ012.
Coastal Flood Advisory from 6 AM Friday to 1 AM EDT Saturday
for MDZ015-019-020.
MARINE...Gale Warning from 6 AM Friday to 6 AM EDT Saturday for ANZ430-
431-450>455.
Small Craft Advisory until 6 AM EDT Friday for ANZ450>452.
Small Craft Advisory until 6 AM EDT Friday for ANZ453>455.
&&
SYNOPSIS...Fitzsimmons/Wunderlin
NEAR TERM...Deal/Johnson
SHORT TERM...Fitzsimmons/OHara
LONG TERM...Fitzsimmons/OHara
AVIATION...Deal/Fitzsimmons/Johnson
MARINE...Deal/Fitzsimmons/Johnson
TIDES/COASTAL FLOODING...Preliminary Local Storm Report
National Weather Service Mount Holly NJ
517 PM EDT Thu Aug 8 2024
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0445 PM Flood 2 S Eastburn Heights 39.69N 75.68W
08/08/2024 New Castle DE Dept of Highways
Flooding on Rt 4 in Ogletown and Brookbend.
&&Preliminary Local Storm Report
National Weather Service Mount Holly NJ
527 PM EDT Thu Aug 8 2024
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0516 PM Rain 2 SW Glendale 39.61N 75.70W
08/08/2024 M5.15 Inch New Castle DE Mesonet
Mesonet station GW1337 BEAR.
0520 PM Rain 2 ENE Glasgow 39.62N 75.71W
08/08/2024 M2.42 Inch New Castle DE Mesonet
Mesonet station AR962 Newark.
&&
GorseThe Dover AFB radar (KDOX), 110 km away, was scanning. The volume nearest the first event began at 21:43 UTC.
4 flash flood, 1 thunderstorm wind. Local standard time, as filed.
Roads around Landenberg were flooded to the point of being impassable.
A road in Toughkenamon was flooded with water approximately 1 foot deep. Picture shared through social media.
Broadcast media shows multiple roads in Kennett Square were closed due to flash flooding. Time estimated from radar.
Multiple water rescues occurred due to vehicles becoming stuck in high water in multiple locations around Coatesville. Time estimated based on radar.
A report from mPING: 1-inch tree limbs broken.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Pennsylvania in 2024Every state in 2024This day in weather historyWarnings in Pennsylvania, August 2024
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: 1214579, 1214582, 1214589, 1214585, 1208824.