A strong shortwave and surface trough approached eastern Pennsylvania. The incoming disturbance encountered a very warm, moist, and unstable airmass.
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 strong shortwave and surface trough approached eastern Pennsylvania. The incoming disturbance encountered a very warm, moist, and unstable airmass. The result was several strong to severe thunderstorms developing, producing damaging wind gusts and downing several trees and power lines in eastern Pennsylvania. Large hail was also reported.
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 Jul 16, 12:15 PM EST, 2 hours 55 minutes earlier.
Area Forecast Discussion
National Weather Service Mount Holly NJ
115 PM EDT Tue Jul 16 2024
.SYNOPSIS...
A thermal trough will remain in place across the East Coast through
Wednesday as Bermuda high pressure remains offshore. A cold front
is expected to move across the Mid Atlantic states Wednesday night
into Thursday, and likely stall to our south through the weekend.
High pressure may briefly build into the area Friday, before diminishing
Saturday into Sunday as a weak cold front approaches from the north.
High pressure may build into the region early next week.
&&
.NEAR TERM /THROUGH TONIGHT/...
No changes to the current forecast with heat and humidity on
full blast.
Bermuda high pressure remains in control and dangerously hot
and humid air continues to spread into the region. High
temperatures will climb well into the 90s, and will be around
100 degrees along the I-95 corridor and into Delmarva. Cooler
temperatures can be found in the mountains of the southern
Poconos and along the coasts, where highs will be in the 80s.
Surface dew points start out in the low to mid 70s, but with
southwest winds increasing to 10 to 15 mph with 20 to 25 mph
gusts, there should be enough mixing for dew points to drop back
into the upper 60s to low 70s. This will still yield max heat
index values from 100 to 110. Heat Advisories and Excessive Heat
Warnings remain in effect for all but the coastal strip of New
Jersey.
Strong shortwave energy along with a thermal trough will
approach from the west Tuesday afternoon. SB CAPE values over
the area will be well in excess of 1500 J/kg, and may even be in
excess of 2500 J/kg. 0-6 km Bulk Shear will average 25 to 30
kt, and PWATs will be up around 2 inches. Even DCAPE values will
be up around 1200 J/kg. The Storm Prediction Center has most of
the region in a Sight Risk (2 out of 5) for severe weather this
afternoon and evening. Hi-res guidance showing thunderstorms
moving into the region late in the afternoon, and damaging wind
gusts, heavy rain, and frequent cloud to ground lightning
strikes can be expected. Hail is also possible.
Showers and thunderstorms taper off by midnight. Warm and humid
again tonight with lows in the 70s, though not much below 80 in
and around Philadelphia.
&&
.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
Hot and humid conditions to a dangerous degree Wednesday before
a transition to more normal temperatures by the end of the
short term. Humidity levels will lower Thursday too, so after
all the recent extreme heat, a welcome break arrives Thursday.
As is usually the case, the transition will be accompanied by
showers/tstms. We'll continue with the likely and low
categorical pops across the area Wed/Wed night then only a
chance for the ern/sern areas Thu morning. The latest Day2
outlook from SPC keep most of the region in a SLIGHT risk for
severe weather, much like Day1. Wind and heavy rains appear the
main threats with a smaller threat for large hail. Most of the
severe weather parameters (CAPE and shear) will hit the marks
for strong storms, so prepare for a second day of eventful
weather Wednesday. Highs again low/mid 90s with heat index
values 100-110 expected most areas but some lower values for the
far NW where arriving clouds may keep values a bit lower.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
The thickest of the heat and humidity will have moved away
providing the region somewhat of a break during the long term.
This is the warmest part of the year climatologically, so even
readings near normal are mostly mid/upper 80s for highs across
the region. The humidity levels during the upcoming period will
be lower than the near/early short term periods, so even with
the expected 'near normal' temperatures, a more comfortable feel
to the air is expected. Heat headlines will not be required. :)
These changes will be the result of the upper high to the
east/southeast relaxing somewhat and an weak upper trough
visiting the Northeast and northern Middle Atlantic areas. There
are indications that beyond next Tue/Wed that the upper ridge
may return. Hopefully with a less powerful punch.
Precipitation looks scarce during the period. Friday looks dry
but a weak front may bring a few showers Sat/Sun for the srn NJ
and Delmarva areas. The dynamics are limited, so only a few
areas will get some light QPF. More scattered showers on Monday,
but only slight chance pops for most spots. Better chances for
rains await for Tue and towards the middle of next week when
tstms will return with the heat.
&&
.AVIATION /17Z TUESDAY THROUGH SATURDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.
Rest of this afternoon (through 00Z)...VFR early this afternoon.
Late day SHRA/TSRA possible, starting primarily after 21Z. Will
include TEMPO TSRA group for KRDG/KABE and a VCTS/PROB30 group
for KTTN/KPNE/KPHL/KILG. Wind gusts in excess of 40 kt and VSBYs
less than 1SM in heavy rain possible in the strongest storms.
SW winds 5 to 10 kt, increasing to 10 to 15 kt with 20 to 25 kt
gusts by midday. Moderate confidence overall.
Tonight...SHRA/TSRA taper off by 04Z. VFR overall. SW winds 5
to 10 kt. Moderate confidence.
Outlook...
Wednesday-Wednesday night...Mostly VFR. Showers and
thunderstorms likely later in the day and into the evening which
could temporarily lead to lower conditions.
Thursday...Mostly VFR. Chance of showers and thunderstorms during
the morning for KMIV/KACY which could temporarily lead to lower
conditions.
Thursday night thru Friday night...VFR conditions expected.
Patchy fog possible during both overnights.
Saturday...Mostly VFR.
&&
.MARINE...
Although conditions may approach Small Craft Advisory criteria
later today, it looks like conditions will fall just short. SW
winds 10 to 15 kt, increasing to 15 to 20 kt this afternoon,
then diminishing to 10 to 15 kt tonight. Seas 3 to 4 feet.
Late day and evening showers and thunderstorms will produce
wind gusts in excess of 40 kt, frequent lightning strikes, and
VSBY restrictions less than 1 NM in heavy rain. Small hail also
possible.
Patchy fog on the waters may restrict VSBYs down to 1 NM.
Outlook...
Wednesday-Wednesday night...Small Craft Advisory conditions possible
with wind gusts near 25 knots and seas near 5 feet.
Thursday-Saturday...Conditions drop below advisory levels early
Thursday and remain below advisory levels through Saturday.
Rip Currents...
For Tuesday, south to southwest flow will average 10 to 15 mph.
Gusts up to 20 mph are possible during the daytime hours. Wave
heights will average 1 to 3 feet and a 5 to 7 second period.
Therefore, there is a MODERATE RISK for the development of
dangerous and life threatening rip currents for the Jersey Shore
in Ocean, Atlantic, and Cape May counties, and a LOW risk for
the Jersey Shore in Monmouth county and Delaware Beaches.
Late day showers and thunderstorms are possible, mainly for the
Jersey Shore in Monmouth and Ocean counties.
For Wednesday, the south-southwest flow will increase to around
15-20 mph with gusts up to 25 mph. Wave heights in the surf
zone are again forecast to be around 1-3 feet with a 5-7 second
period. Therefore, a MODERATE RISK for the development of
dangerous and life threatening rip currents is again in place
for the Jersey Shore in Ocean, Atlantic, and Cape May counties,
and a LOW risk for the Jersey Shore in Monmouth county and
Delaware Beaches.
Some areas of fog at times will cause reduced visibility along
the shoreline.
For specific beach forecasts, visit weather.gov/beach/phi
&&
.CLIMATE...
Georgetown and Reading tied their record highs for yesterday July
15th. Georgetown also tied its record warm lowest temperature for
Monday with 75 degrees. For today and Wednesday, near record breaking
temperatures (both highs and lows) are possible. We've included the
records for our climate sites below.
Record High Temperatures (today)
July 16
Site Record/Year
Allentown (ABE) 101/1988
AC Airport (ACY) 100/1983
AC Marina (55N) 100/1983
Georgetown (GED) 97/1953 & 1992
Mount Pocono (MPO) 93/1988
Philadelphia (PHL) 102/1988
Reading (RDG) 100/1900
Trenton (TTN) 102/1988
Wilmington (ILG) 100/1983
Record Warmest Low Temperatures (today)
July 16
Site Record/Year
Allentown (ABE) 76/1983
AC Airport (ACY) 77/1983
AC Marina (55N) 80/2013
Georgetown (GED) 80/1955
Mount Pocono (MPO) 70/1955
Philadelphia (PHL) 80/2013
Reading (RDG) 78/1955
Trenton (TTN) 78/1983
Wilmington (ILG) 77/2013
Record High Temperatures (Wednesday)
July 17
Site Record/Year
Allentown (ABE) 99/1999
AC Airport (ACY) 99/2012
AC Marina (55N) 95/1937
Georgetown (GED) 100/2019
Mount Pocono (MPO) 91/1999
Philadelphia (PHL) 102/1988
Reading (RDG) 102/1988
Trenton (TTN) 100/1988
Wilmington (ILG) 100/1988
&&
.PHI WATCHES/WARNINGS/ADVISORIES...
PA...Excessive Heat Warning until 8 PM EDT Wednesday for PAZ060>062-
070-071-101>106.
Heat Advisory until 8 PM EDT Wednesday for PAZ054-055.
NJ...Excessive Heat Warning until 8 PM EDT Wednesday for NJZ007>010-
012-013-015>020-027.
Heat Advisory until 8 PM EDT Wednesday for NJZ001-014-021>023.
DE...Excessive Heat Warning until 8 PM EDT Wednesday for DEZ001>003.
Heat Advisory until 8 PM EDT Wednesday for DEZ004.
MD...Excessive Heat Warning until 8 PM EDT Wednesday for MDZ012-015-
019-020.
MARINE...None.
&&
SYNOPSIS...Robertson
NEAR TERM...MJL/MPS
SHORT TERM...OHara
LONG TERM...OHara
AVIATION...MJL/MPS/OHara
MARINE...MPS/OHara
CLIMATE...The State College radar (KCCX), 158 km away, was scanning. The volume nearest the first event began at 20:11 UTC.
34 thunderstorm wind, 1 hail. Local standard time, as filed.
Report from Bethel Twp: Club Rd and Faust Rd - Wires Down. Time estimated.
Reports of multiple trees down all along Centerport Rd in Centre Twp. Time estimated.
Report from Wernersville Boro: W Penn Ave - Tree on Wires. Time estimated.
Report from Spotter Network: Several large tree branches, roughly 6 inches in diameter, blown down in Lower Heidelberg Twp. Portions of the area remain without power. Time estimated.
Report from South Heidelberg Twp: E Penn Ave - Wires Down on a Vehicle. Time estimated.
Large tree limb down in driveway in Lower Heidelberg Twp. Time estimated by radar.
A report from mPing. Time updated based on radar.
Power pole snapped on Exeter Street in Reading with wires down. Time estimated from radar.
Tree down lying across Lobachsville Rd in New Jerusalem. Time estimated.
Reports of a few trees down on power lines in southern Whitehall Township. Time estimated.
Tree down lying across Parkway Blvd by Cedar Creek in Allentown. Time estimated.
Damage to nursing home and wires down nearby. Time estimated by radar. No injuries reported at this time.
Trees reported down. Time estimated from radar.
Downed tree in wires on Slifer Valley Road and Lehnenberg Road in both directions at Durham Road. Time estimated from radar.
Downed tree in wires on Slifer Valley Road and Lehnenberg Road in both direction at Gallows Hill Road. Time estimated from radar.
EM reported numerous trees down along Route 611 from Bedminster Township to Riegelsville Borough. A tree fell onto a Fire Chiefs vehicle while responding to a call and the chiefs vehicle overturned and he was injured. Time estimated from radar.
EM reports numerous trees and wires down in Nockamixon Township. Some utility poles were snapped at ground level. Time estimated from radar.
Photos sent showing several snapped trees and other significant tree damage in Upper Black Eddy Township near Marienstein Road and Lonely Cottage Road. Time estimated.
A few reports of trees down on power lines across Upper Saucon Township. Time estimated.
Trees down in Honey Brook. Time estimated from radar.
Trees down in West Brandywine Twp. Time estimated from radar.
Several trees down. Pictures shared on social media. Time estimated from radar.
Large tree snapped and fell onto a house on French Road in Perkiomen Township. Time estimated from radar.
Delayed storm damage report. Large pine tree snapped at the trunk, fell onto house collapsing a portion of the roof on Bridge Street in Perkiomen Township. About a half dozen trees on the north side of Bridge Street also had split trunks. Time estimated.
Large tree limb in excess of 6 inches in diameter down. Also video of what looks to be estimated 60 mph winds. Time estimated.
Numerous reports of trees and wires down in western Chester County relayed by EM. Time estimated from radar.
Trees down with estimated 60 mph wind gusts. Time estimated from radar.
Trees down in King of Prussia. Time estimated from radar.
Trees reported down. Time estimated from radar.
Several large tree limbs down and also a tree down blocking a roadway. Time estimated from radar.
Video of large branches and limbs snapped off trees in Glenside PA. Time estimated.
Tree split on Ridge Road near Tally Ho Drive. Time estimated from radar.
Tree on car on 1900 block of Welsh Road. Time estimated from radar.
Tree split on 1500 block of Creswood Rd. Time estimated from radar.
Several trees down along Woodhaven Road in Northeast Philadelphia. Time estimated by radar.
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, July 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 2026-10-01. Each event’s entry at NCEI: 1206439, 1206440, 1206441, 1206442, 1206443, 1206444, 1206445, 1206446, 1206447, 1206448, 1206449, 1206450, 1206451, 1206452, 1206453, 1206454, 1206455, 1206456, 1206457, 1206458, 1206459, 1206460, 1206461, 1206462, 1206463, 1206464, 1206465, 1206466, 1206467, 1206468, 1206469, 1206470, 1206471, 1206472, 1206473.