A warm and very humid air mass was in place over the mid-Atlantic on July 17. A warm front which had sagged south into the region on the night of the 16th pushed back to the north on the morning of the 17th.
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 warm and very humid air mass was in place over the mid-Atlantic on July 17. A warm front which had sagged south into the region on the night of the 16th pushed back to the north on the morning of the 17th. Meanwhile, a cold front slowly approached by evening, with a pre-frontal surface trough ahead of it. The presence of multiple synoptic and mesoscale boundaries led to a highly complex convective evolution. Several areas and multiple rounds of convection affected the eastern mid-Atlantic over about a 12 hour period from early afternoon on the 17th to a little after midnight on the 18th. With shear falling in the weak to moderate range, convection mainly took the form of multi-cellular and linear clusters, though some semi-discrete supercellular structures were noted at times. A number of storms became severe with damaging wind. A weak tornado was confirmed in Burlington County, NJ in association with a line of thunderstorms in the later evening. Areas of heavy rain and flash flooding also occurred due to the widespread and at times slow moving nature of the convection. Eventually, by later in the night, the approach of the cold front and significant overturning of the atmosphere from the day's convection caused remaining activity to weaken and shift offshore.
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 17, 10:01 AM EST, 2 hours 14 minutes earlier.
Area Forecast Discussion
National Weather Service Mount Holly NJ
1101 AM EDT Sat Jul 17 2021
.SYNOPSIS...
Low pressure currently located over Indiana will head east towards
New York this afternoon with a cold front extending south across
central Pennsylvania. The cold front will then clear the New Jersey
coast Sunday morning. Another cold front is anticipated to cross New
Jersey Wednesday night.
&&
.NEAR TERM /THROUGH TONIGHT/...
A few showers developed earlier near Allentown and across
Hunterdon County NJ. This is likely near to the weak boundary
across the area. Except for raising pops up a bit, few changes
were added to the ongoing fcst.
An active weather day is forecast across the forecast area
today with flash flooding and damaging winds possible from
thunderstorms.
A mid-level shortwave trough across the Ohio Valley will approach
the region into this evening. An associated weak surface low currently
in the same region will also approach from the west throughout the
day. A weak mid-level low is forecast to close off somewhere across
the southern Great Lakes region as the day progresses as well.
A weak boundary across the area will drift slowly north and will
play a key role in exactly where convection develops into the
afternoon and thus where the greatest flash flood and severe
weather threats will be located. A slow moving frontal boundary
will also approach the region tonight in the wake of the
widespread convection that is expected.
As MLCAPE builds to over 2000 J/kg and southerly flow increases
across the area, convection is anticipated to initiate near the
slowly moving boundary into this afternoon (likely 2 PM or later) in
the areas from around the Philly metro and north to near the I-78
corridor. This convection will precede the greatest mid-level flow
and forcing and therefore should be fairly pulsy in nature with
deep effective shear 20 kts or less. Modest DCAPE in the 800 J/kg
neighborhood will lead to a microburst potential with any of this
initial convection during the afternoon hours. There will be some
very subtle low-level (0-1 km) shear around 10-15 kts in the
environment this afternoon, so there is also a non-zero tornado
potential. I think this could present itself in more of a landspout
or waterspout threat rather than a mesocyclonic tornado threat. Mid-
level lapse rates have trended slightly higher in the latest
guidance, thus the thinking is that the severe weather potential
(primarily in the form of damaging winds) could be a bit more
widespread than originally expected. This will also play a role in
the second round of convection (more details on this follow). SPC
has increased the severe risk to Slight for portions of the area.
Given that the best mid-level flow will not have arrived early in
the event this afternoon, the convection may train over the same
locations as outflow boundaries interact with the initial boundary
forcing the convection. This will probably result in the greatest
flash flooding threat area wherever this activity sets up as
Precipitable Water values will be near 2". Rainfall rates may
locally exceed 2"/hour. WPC continues to highlight portions of the
area in a moderate risk for excessive rainfall and the Flash Flood
Watch continues for the urban corridor and all locations north of
there.
The greatest forcing associated with the shortwave trough is
forecast to arrive later in the afternoon and into the evening.
The approaching shortwave will also result in stronger mid-level
flow with effective deep shear increasing closer to 30 kts. This
should result in convection generally becoming more organized into
the evening. Many of the CAM guidance solutions indicate a line or
broken line of convection developing and moving offshore in the 6-10
PM timeframe. This secondary round of activity would also bring
primarily a damaging wind threat, but could also produce additional
heavy rainfall over areas that may have already received a good
drenching from the first round of activity.
Long story short, widespread convection is expected in the forecast
area, especially along and north/west of I-95. Temperatures will
once again rise into the low to mid 90s with low 70s dewpoints. The
Heat Advisory remains in effect today with maximum Heat Indicies
rising to near 100 degrees near and south of Philly. Values nearing
105 degrees across the eastern shore of Maryland have prompted an
expansion of the advisory into this area.
The showers and thunderstorms should linger for some time into the
overnight period, but should generally wane in intensity and
coverage after midnight, especially after the more organized line
moves offshore. Expect another muggy night with lows in the low
70s.
&&
.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
Sunday morning an area of low pressure will be located across New
York with a surface cold front extending south over eastern PA, MD,
and VA. Latest guidance continues to push the cold front offshore by
Sunday afternoon as mid-level low pressure nudges east. As the cold
front crosses the area late Sunday morning, there is a slight chance
of showers with the frontal passage, but chances look low as dry air
rapidly filters in from the west. Forecast soundings also show a
potent inversion forming in the 700/800 MB layer (helping to
suppress convective initiation). Behind the cold front, much drier
mid-level air will wash over the region with PWATs falling towards
1.15" (slightly below median values for this time of year). At the
surface, temperatures will be about 5 to 10 degrees cooler than
Saturday, or near normal for this time of year. Towards the Poconos
expect highs in the mid 70s, with the warmest places being along the
coastal zones with highs in the mid to upper 80s (thanks to a
westerly wind preventing a sea breeze from moving inland).
By Monday, the closed low that was over New York Sunday will
continue to slowly progress east towards Maine. Mostly dry
conditions are forecast as the region falls on the ageostrophic
convergent region of the trough axis. Expect high temperatures
in the mid 80s as 850 MB temperatures hold around 13 degrees C.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
For the remainder of the work week, a long wave trough axis will
center across the eastern United States as a potent mid-level ridge
amplifies over the western United States. Expect temperatures mostly
near normal for the period with the best chance of precipitation
being Wednesday night in association with a surface cold front
passage.
On Tuesday, the mid-level low will be shunted east off the coast of
the United States as a stronger mid-level wave heads southeast out
of Quebec. A surface cold front will dive southeast in association
with the wave bringing the next chance of showers and thunderstorms
to the region Wednesday evening. Ahead of the front Wednesday,
temperatures will approach 90 degrees. The front will clear the
coast Thursday morning and bring temperatures back down towards
normal for Thursday and Friday.
&&
.AVIATION /15Z SATURDAY THROUGH WEDNESDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE,
KRDG, KILG, KMIV, KACY and surrounding areas.
Today...Prevailing VFR, but thunderstorms with heavy rain and gusty
winds are expected to develop after 18Z, especially near and
north/west of the I-95 corridor. Restrictions likely in these areas
associated with convection, but the exact timing and placement of
thunderstorms locally at each terminal is not certain. Therefore,
have kept a prevailing VCTS group and TEMPO +TSRA group for all
terminals with the most likely period of restrictions. The TEMPO
groups will probably need to be adjusted in future TAF issuances.
Winds initially light and variable will increase to near 10 kts from
the south after 15Z. Some gusts of 15-20 kts possible along and
south/east of I-95 terminals. High confidence overall on
thunderstorm potential and winds, but low confidence on exact timing
of restrictions due to thunderstorms.
Tonight...Initially prevailing VFR with lingering showers after 03Z,
but ceilings will lower to MVFR at some terminals. Winds south to
southwesterly around 5 kts. Moderate confidence.
Outlook...
Sunday...Some low clouds and fog are possible in the morning.
Showers and possibly a thunderstorm could occur along a cold front
as it crosses the terminals. VFR clouds persisting through the
afternoon with winds turning from the west. Gusts of 15 to 20 knots
possible. Medium confidence.
Monday and Tuesday...Mainly VFR. Westerly winds 5 to 10 knots.
Medium confidence.
Wednesday... Another cold front will approach the area from the
northwest Wednesday evening. Showers and thunderstorms possible.
Mainly VFR conditions with lower cigs and vsbys possible with the
frontal passage. Medium confidence.
&&
.MARINE...
Saturday...Sub-advisory conditions expected with southwesterly winds
around 15 kts increasing to around 20 kts late. Showers and
thunderstorms expected this evening with heavy rain and locally
higher winds and seas possible. Seas 3-4 feet.
Outlook...
Sunday through Wednesday...Mostly sub-sca conditions. Seas 2 to 4 ft
are expected on the ocean and 1 to 2 ft for the Delaware Bay. A cold
front will cross the waters Wednesday night bringing a chance of
showers and thunderstorms.
Rip Currents...
Southerly winds and swell will increase today with winds around 20
mph by this afternoon. Winds will become more southwesterly on
Sunday with speeds around 10-15 mph. Breaking waves are forecast to
be 2 to 3 feet with a medium period southerly swell today. Breaking
waves decrease to around 1 to 2 feet for Sunday. As a result, the
rip current risk is MODERATE today for the more southerly facing
beaches of Cape May, Atlantic, and Ocean Counties, but will be low
for Monmouth and Sussex County beaches. For Sunday, we'll maintain
MODERATE for Cape May and Atlantic County beaches with low
elsewhere, but the risk will generally decrease throughout the day
as the southerly swell wanes.
&&
.PHI WATCHES/WARNINGS/ADVISORIES...
PA...Heat Advisory until 8 PM EDT this evening for PAZ070-071-
101>106.
Flash Flood Watch from 2 PM EDT this afternoon through late
tonight for PAZ054-055-060>062-070-071-101>106.
NJ...Heat Advisory until 8 PM EDT this evening for NJZ008>010-
012>020-027.
Flash Flood Watch from 2 PM EDT this afternoon through late
tonight for NJZ001-007>010-012>020-026-027.
DE...Heat Advisory until 8 PM EDT this evening for DEZ001.
Flash Flood Watch from 2 PM EDT this afternoon through late
tonight for DEZ001.
MD...Heat Advisory until 8 PM EDT this evening for MDZ012-015-019-
020.
MARINE...None.
&&
Synopsis...Haines
Near Term...Staarmann/po
Short Term...Haines
Long Term...Haines
Aviation...Haines/Staarmann
Marine...Haines/StaarmannHazardous Weather Outlook National Weather Service Mount Holly NJ 1102 AM EDT Sat Jul 17 2021 DEZ001-181502- New Castle- 1102 AM EDT Sat Jul 17 2021 This Hazardous Weather Outlook is for New Castle County in Delaware. .DAY ONE...Through tonight. Please listen to NOAA Weather Radio or go to weather.gov on the Internet for more information about the following hazards. Heat Advisory. Flash Flood Watch. .DAYS TWO THROUGH SEVEN...Sunday through Friday. The probability for widespread hazardous weather is low. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures. DEZ002-181502- Kent- 1102 AM EDT Sat Jul 17 2021 This Hazardous Weather Outlook is for Kent County in Delaware. .DAY ONE...Through tonight. Several instances of flooding are possible, especially in urban and poor-drainage areas and near vulnerable small creeks and streams. Scattered severe thunderstorms are possible. Please go to weather.gov/phi/ehwo for more information on potential weather hazards. .DAYS TWO THROUGH SEVEN...Sunday through Friday. Minor coastal flooding is possible on Tuesday. Please go to weather.gov/phi/ehwo for more information on potential weather hazards. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures. DEZ003-181502- Inland Sussex- 1102 AM EDT Sat Jul 17 2021 This Hazardous Weather Outlook is for inland portions of Sussex County in Delaware. .DAY ONE...Through tonight. There is a low probability of widespread hazardous weather. .DAYS TWO THROUGH SEVEN...Sunday through Friday. Minor coastal flooding is possible on Tuesday. Please go to weather.gov/phi/ehwo for more information on potential weather hazards. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures. DEZ004-181502- Delaware Beaches- 1102 AM EDT Sat Jul 17 2021 This Hazardous Weather Outlook is for the Atlantic coastal portions of Sussex County in Delaware. .DAY ONE...Through tonight. There is a low probability of widespread hazardous weather. .DAYS TWO THROUGH SEVEN...Sunday through Friday. Minor coastal flooding is possible on Tuesday. Please go to weather.gov/phi/ehwo for more information on potential weather hazards. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures. PAZ054-181502- Carbon- 1102 AM EDT Sat Jul 17 2021 This Hazardous Weather Outlook is for Carbon County in Pennsylvania. .DAY ONE...Through tonight. Please listen to NOAA Weather Radio or go to weather.gov on the Internet for more information about the following hazards. Flash Flood Watch. .DAYS TWO THROUGH SEVEN...Sunday through Friday. The probability for widespread hazardous weather is low. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures. PAZ055-181502- Monroe- 1102 AM EDT Sat Jul 17 2021 This Hazardous Weather Outlook is for Monroe County in Pennsylvania. .DAY ONE...Through tonight. Please listen to NOAA Weather Radio or go to weather.gov on the Internet for more information about the following hazards. Flash Flood Watch. .DAYS TWO THROUGH SEVEN...Sunday through Friday. The probability for widespread hazardous weather is low. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures. PAZ060-181502- Berks- 1102 AM EDT Sat Jul 17 2021 This Hazardous Weather Outlook is for Berks County in Pennsylvania. .DAY ONE...Through tonight. Please listen to NOAA Weather Radio or go to weather.gov on the Internet for more information about the following hazards. Flash Flood Watch. .DAYS TWO THROUGH SEVEN...Sunday through Friday. The probability for widespread hazardous weather is low. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures. PAZ061-181502- Lehigh- 1102 AM EDT Sat Jul 17 2021 This Hazardous Weather Outlook is for Lehigh County in Pennsylvania. .DAY ONE...Through tonight. Please listen to NOAA Weather Radio or go to weather.gov on the Internet for more information about the following hazards. Flash Flood Watch. .DAYS TWO THROUGH SEVEN...Sunday through Friday. The probability for widespread hazardous weather is low. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures. PAZ062-181502- Northampton- 1102 AM EDT Sat Jul 17 2021 This Hazardous Weather Outlook is for Northampton County in Pennsylvania. .DAY ONE...Through tonight. Please listen to NOAA Weather Radio or go to weather.gov on the Internet for more information about the following hazards. Flash Flood Watch. .DAYS TWO THROUGH SEVEN...Sunday through Friday. The probability for widespread hazardous weather is low. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures. PAZ070-181502- Delaware- 1102 AM EDT Sat Jul 17 2021 This Hazardous Weather Outlook is for Delaware County in Pennsylvania. .DAY ONE...Through tonight. Please listen to NOAA Weather Radio or go to weather.gov on the Internet for more information about the following hazards. Heat Advisory. Flash Flood Watch. .DAYS TWO THROUGH SEVEN...Sunday through Friday. The probability for widespread hazardous weather is low. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures. PAZ071-181502- Philadelphia- 1102 AM EDT Sat Jul 17 2021 This Hazardous Weather Outlook is for Philadelphia County in Pennsylvania. .DAY ONE...Through tonight. Please listen to NOAA Weather Radio or go to weather.gov on the Internet for more information about the following hazards. Heat Advisory. Flash Flood Watch. .DAYS TWO THROUGH SEVEN...Sunday through Friday. The probability for widespread hazardous weather is low. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures. PAZ101-181502- Western Chester- 1102 AM EDT Sat Jul 17 2021 This Hazardous Weather Outlook is for western Chester County in Pennsylvania. .DAY ONE...Through tonight. Please listen to NOAA Weather Radio or go to weather.gov on the Internet for more information about the following hazards. Heat Advisory. Flash Flood Watch. .DAYS TWO THROUGH SEVEN...Sunday through Friday. The probability for widespread hazardous weather is low. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures. PAZ102-181502- Eastern Chester- 1102 AM EDT Sat Jul 17 2021 This Hazardous Weather Outlook is for eastern Chester County in Pennsylvania. .DAY ONE...Through tonight. Please listen to NOAA Weather Radio or go to weather.gov on the Internet for more information about the following hazards. Heat Advisory. Flash Flood Watch. .DAYS TWO THROUGH SEVEN...Sunday through Friday. The probability for widespread hazardous weather is low. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures. PAZ103-181502- Western Montgomery- 1102 AM EDT Sat Jul 17 2021 This Hazardous Weather Outlook is for western Montgomery County in Pennsylvania. .DAY ONE...Through tonight. Please listen to NOAA Weather Radio or go to weather.gov on the Internet for more information about the following hazards. Heat Advisory. Flash Flood Watch. .DAYS TWO THROUGH SEVEN...Sunday through Friday. The probability for widespread hazardous weather is low. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures. PAZ104-181502- Eastern Montgomery- 1102 AM EDT Sat Jul 17 2021 This Hazardous Weather Outlook is for eastern Montgomery County in Pennsylvania. .DAY ONE...Through tonight. Please listen to NOAA Weather Radio or go to weather.gov on the Internet for more information about the following hazards. Heat Advisory. Flash Flood Watch. .DAYS TWO THROUGH SEVEN...Sunday through Friday. The probability for widespread hazardous weather is low. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures. PAZ105-181502- Upper Bucks- 1102 AM EDT Sat Jul 17 2021 This Hazardous Weather Outlook is for upper Bucks County in Pennsylvania. .DAY ONE...Through tonight. Please listen to NOAA Weather Radio or go to weather.gov on the Internet for more information about the following hazards. Heat Advisory. Flash Flood Watch. .DAYS TWO THROUGH SEVEN...Sunday through Friday. The probability for widespread hazardous weather is low. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures. PAZ106-181502- Lower Bucks- 1102 AM EDT Sat Jul 17 2021 This Hazardous Weather Outlook is for lower Bucks County in Pennsylvania. .DAY ONE...Through tonight. Please listen to NOAA Weather Radio or go to weather.gov on the Internet for more information about the following hazards. Heat Advisory. Flash Flood Watch. .DAYS TWO THROUGH SEVEN...Sunday through Friday. The probability for widespread hazardous weather is low. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures. NJZ001-181502- Sussex- 1102 AM EDT Sat Jul 17 2021 This Hazardous Weather Outlook is for Sussex County in New Jersey. .DAY ONE...Through tonight. Please listen to NOAA Weather Radio or go to weather.gov on the Internet for more information about the following hazards. Flash Flood Watch. .DAYS TWO THROUGH SEVEN...Sunday through Friday. The probability for widespread hazardous weather is low. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures. NJZ007-181502- Warren- 1102 AM EDT Sat Jul 17 2021 This Hazardous Weather Outlook is for Warren County in New Jersey. .DAY ONE...Through tonight. Please listen to NOAA Weather Radio or go to weather.gov on the Internet for more information about the following hazards. Flash Flood Watch. .DAYS TWO THROUGH SEVEN...Sunday through Friday. The probability for widespread hazardous weather is low. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures. NJZ008-181502- Morris- 1102 AM EDT Sat Jul 17 2021 This Hazardous Weather Outlook is for Morris County in New Jersey. .DAY ONE...Through tonight. Please listen to NOAA Weather Radio or go to weather.gov on the Internet for more information about the following hazards. Heat Advisory. Flash Flood Watch. .DAYS TWO THROUGH SEVEN...Sunday through Friday. The probability for widespread hazardous weather is low. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures. NJZ009-181502- Hunterdon- 1102 AM EDT Sat Jul 17 2021 This Hazardous Weather Outlook is for Hunterdon County in New Jersey. .DAY ONE...Through tonight. Please listen to NOAA Weather Radio or go to weather.gov on the Internet for more information about the following hazards. Heat Advisory. Flash Flood Watch. .DAYS TWO THROUGH SEVEN...Sunday through Friday. The probability for widespread hazardous weather is low. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures. NJZ010-181502- Somerset- 1102 AM EDT Sat Jul 17 2021 This Hazardous Weather Outlook is for Somerset County in New Jersey. .DAY ONE...Through tonight. Please listen to NOAA Weather Radio or go to weather.gov on the Internet for more information about the following hazards. Heat Advisory. Flash Flood Watch. .DAYS TWO THROUGH SEVEN...Sunday through Friday. The probability for widespread hazardous weather is low. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures. NJZ012-181502- Middlesex- 1102 AM EDT Sat Jul 17 2021 This Hazardous Weather Outlook is for Middlesex County in New Jersey. .DAY ONE...Through tonight. Please listen to NOAA Weather Radio or go to weather.gov on the Internet for more information about the following hazards. Heat Advisory. Flash Flood Watch. .DAYS TWO THROUGH SEVEN...Sunday through Friday. The probability for widespread hazardous weather is low. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures. NJZ013-181502- Western Monmouth- 1102 AM EDT Sat Jul 17 2021 This Hazardous Weather Outlook is for western Monmouth County in New Jersey. .DAY ONE...Through tonight. Please listen to NOAA Weather Radio or go to weather.gov on the Internet for more information about the following hazards. Heat Advisory. Flash Flood Watch. .DAYS TWO THROUGH SEVEN...Sunday through Friday. The probability for widespread hazardous weather is low. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures. NJZ014-181502- Eastern Monmouth- 1102 AM EDT Sat Jul 17 2021 This Hazardous Weather Outlook is for eastern Monmouth County in New Jersey. .DAY ONE...Through tonight. Please listen to NOAA Weather Radio or go to weather.gov on the Internet for more information about the following hazards. Heat Advisory. Flash Flood Watch. .DAYS TWO THROUGH SEVEN...Sunday through Friday. Minor coastal flooding is possible on Tuesday. Please go to weather.gov/phi/ehwo for more information on potential weather hazards. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures. NJZ015-181502- Mercer- 1102 AM EDT Sat Jul 17 2021 This Hazardous Weather Outlook is for Mercer County in New Jersey. .DAY ONE...Through tonight. Please listen to NOAA Weather Radio or go to weather.gov on the Internet for more information about the following hazards. Heat Advisory. Flash Flood Watch. .DAYS TWO THROUGH SEVEN...Sunday through Friday. The probability for widespread hazardous weather is low. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures. NJZ016-181502- Salem- 1102 AM EDT Sat Jul 17 2021 This Hazardous Weather Outlook is for Salem County in New Jersey. .DAY ONE...Through tonight. Please listen to NOAA Weather Radio or go to weather.gov on the Internet for more information about the following hazards. Heat Advisory. Flash Flood Watch. .DAYS TWO THROUGH SEVEN...Sunday through Friday. The probability for widespread hazardous weather is low. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures. NJZ017-181502- Gloucester- 1102 AM EDT Sat Jul 17 2021 This Hazardous Weather Outlook is for Gloucester County in New Jersey. .DAY ONE...Through tonight. Please listen to NOAA Weather Radio or go to weather.gov on the Internet for more information about the following hazards. Heat Advisory. Flash Flood Watch. .DAYS TWO THROUGH SEVEN...Sunday through Friday. The probability for widespread hazardous weather is low. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures. NJZ018-181502- Camden- 1102 AM EDT Sat Jul 17 2021 This Hazardous Weather Outlook is for Camden County in New Jersey. .DAY ONE...Through tonight. Please listen to NOAA Weather Radio or go to weather.gov on the Internet for more information about the following hazards. Heat Advisory. Flash Flood Watch. .DAYS TWO THROUGH SEVEN...Sunday through Friday. The probability for widespread hazardous weather is low. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures. NJZ019-181502- Northwestern Burlington- 1102 AM EDT Sat Jul 17 2021 This Hazardous Weather Outlook is for northwestern Burlington County in New Jersey. .DAY ONE...Through tonight. Please listen to NOAA Weather Radio or go to weather.gov on the Internet for more information about the following hazards. Heat Advisory. Flash Flood Watch. .DAYS TWO THROUGH SEVEN...Sunday through Friday. The probability for widespread hazardous weather is low. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures. NJZ020-181502- Ocean- 1102 AM EDT Sat Jul 17 2021 This Hazardous Weather Outlook is for inland portions of Ocean County in New Jersey. .DAY ONE...Through tonight. Please listen to NOAA Weather Radio or go to weather.gov on the Internet for more information about the following hazards. Heat Advisory. Flash Flood Watch. .DAYS TWO THROUGH SEVEN...Sunday through Friday. Minor coastal flooding is possible on Tuesday. Please go to weather.gov/phi/ehwo for more information on potential weather hazards. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures. NJZ021-181502- Cumberland- 1102 AM EDT Sat Jul 17 2021 This Hazardous Weather Outlook is for Cumberland County in New Jersey. .DAY ONE...Through tonight. Several instances of flooding are possible, especially in urban and poor-drainage areas and near vulnerable small creeks and streams. Scattered severe thunderstorms are possible. Please go to weather.gov/phi/ehwo for more information on potential weather hazards. .DAYS TWO THROUGH SEVEN...Sunday through Friday. The probability for widespread hazardous weather is low. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures. NJZ022-181502- Atlantic- 1102 AM EDT Sat Jul 17 2021 This Hazardous Weather Outlook is for inland portions of Atlantic County in New Jersey. .DAY ONE...Through tonight. Several instances of flooding are possible, especially in urban and poor-drainage areas and near vulnerable small creeks and streams. Please go to weather.gov/phi/ehwo for more information on potential weather hazards. .DAYS TWO THROUGH SEVEN...Sunday through Friday. The probability for widespread hazardous weather is low. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures. NJZ023-181502- Cape May- 1102 AM EDT Sat Jul 17 2021 This Hazardous Weather Outlook is for Cape May County excluding the Atlantic coast in New Jersey. .DAY ONE...Through tonight. There is a low probability of widespread hazardous weather. .DAYS TWO THROUGH SEVEN...Sunday through Friday. Minor coastal flooding is possible on Tuesday. Please go to weather.gov/phi/ehwo for more information on potential weather hazards. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures. NJZ024-181502- Atlantic Coastal Cape May- 1102 AM EDT Sat Jul 17 2021 This Hazardous Weather Outlook is for the Atlantic coastal portions of Cape May County in New Jersey. .DAY ONE...Through tonight. There is a moderate risk of rip currents. Please go to weather.gov/phi/ehwo for more information on potential weather hazards. .DAYS TWO THROUGH SEVEN...Sunday through Friday. Minor coastal flooding is possible on Tuesday. There is a moderate risk of rip currents on Sunday. Please go to weather.gov/phi/ehwo for more information on potential weather hazards. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures. NJZ025-181502- Coastal Atlantic- 1102 AM EDT Sat Jul 17 2021 This Hazardous Weather Outlook is for coastal portions of Atlantic County in New Jersey. .DAY ONE...Through tonight. Please listen to NOAA Weather Radio or go to weather.gov on the Internet for more information about the following hazards. Flash Flood Watch. .DAYS TWO THROUGH SEVEN...Sunday through Friday. There is a moderate risk of rip currents on Sunday. Please go to weather.gov/phi/ehwo for more information on potential weather hazards. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures. NJZ026-181502- Coastal Ocean- 1102 AM EDT Sat Jul 17 2021 This Hazardous Weather Outlook is for coastal portions of Ocean County in New Jersey. .DAY ONE...Through tonight. Please listen to NOAA Weather Radio or go to weather.gov on the Internet for more information about the following hazards. Flash Flood Watch. .DAYS TWO THROUGH SEVEN...Sunday through Friday. Minor coastal flooding is possible on Tuesday. Please go to weather.gov/phi/ehwo for more information on potential weather hazards. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures. NJZ027-181502- Southeastern Burlington- 1102 AM EDT Sat Jul 17 2021 This Hazardous Weather Outlook is for southeastern Burlington County in New Jersey. .DAY ONE...Through tonight. Please listen to NOAA Weather Radio or go to weather.gov on the Internet for more information about the following hazards. Heat Advisory. Flash Flood Watch. .DAYS TWO THROUGH SEVEN...Sunday through Friday. The probability for widespread hazardous weather is low. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures. MDZ012-181502- Kent MD- 1102 AM EDT Sat Jul 17 2021 This Hazardous Weather Outlook is for Kent County in Maryland. .DAY ONE...Through tonight. Please listen to NOAA Weather Radio or go to weather.gov on the Internet for more information about the following hazards. Heat Advisory. .DAYS TWO THROUGH SEVEN...Sunday through Friday. The probability for widespread hazardous weather is low. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures. MDZ015-181502- Queen Annes- 1102 AM EDT Sat Jul 17 2021 This Hazardous Weather Outlook is for Queen Annes County in Maryland. .DAY ONE...Through tonight. Please listen to NOAA Weather Radio or go to weather.gov on the Internet for more information about the following hazards. Heat Advisory. .DAYS TWO THROUGH SEVEN...Sunday through Friday. The probability for widespread hazardous weather is low. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures. MDZ019-181502- Talbot- 1102 AM EDT Sat Jul 17 2021 This Hazardous Weather Outlook is for Talbot County in Maryland. .DAY ONE...Through tonight. Please listen to NOAA Weather Radio or go to weather.gov on the Internet for more information about the following hazards. Heat Advisory. .DAYS TWO THROUGH SEVEN...Sunday through Friday. The probability for widespread hazardous weather is low. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures. MDZ020-181502- Caroline- 1102 AM EDT Sat Jul 17 2021 This Hazardous Weather Outlook is for Caroline County in Maryland. .DAY ONE...Through tonight. Please listen to NOAA Weather Radio or go to weather.gov on the Internet for more information about the following hazards. Heat Advisory. .DAYS TWO THROUGH SEVEN...Sunday through Friday. The probability for widespread hazardous weather is low. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures. ANZ430-181502- Delaware Bay waters north of East Point NJ to Slaughter Beach DE- 1102 AM EDT Sat Jul 17 2021 This Hazardous Weather Outlook is for upper Delaware Bay. .DAY ONE...Through tonight. Scattered severe thunderstorms are possible. Please go to weather.gov/phi/ehwo for more information on potential weather hazards. .DAYS TWO THROUGH SEVEN...Sunday through Friday. The probability for widespread hazardous weather is low. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures. ANZ431-181502- Delaware Bay waters south of East Point NJ to Slaughter Beach DE- 1102 AM EDT Sat Jul 17 2021 This Hazardous Weather Outlook is for lower Delaware Bay. .DAY ONE...Through tonight. The probability for widespread hazardous weather is low. .DAYS TWO THROUGH SEVEN...Sunday through Friday. The probability for widespread hazardous weather is low. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures. ANZ450-181502- Coastal waters from Sandy Hook to Manasquan Inlet NJ out 20 nm- 1102 AM EDT Sat Jul 17 2021 This Hazardous Weather Outlook is for the Atlantic coastal waters adjacent to Monmouth County out 20 nm. .DAY ONE...Through tonight. The probability for widespread hazardous weather is low. .DAYS TWO THROUGH SEVEN...Sunday through Friday. The probability for widespread hazardous weather is low. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures. ANZ451-181502- Coastal waters from Manasquan Inlet to Little Egg Inlet NJ out 20 nm- 1102 AM EDT Sat Jul 17 2021 This Hazardous Weather Outlook is for the Atlantic coastal waters adjacent to Ocean County out 20 nm. .DAY ONE...Through tonight. The probability for widespread hazardous weather is low. .DAYS TWO THROUGH SEVEN...Sunday through Friday. The probability for widespread hazardous weather is low. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures. ANZ452-181502- Coastal waters from Little Egg Inlet to Great Egg Inlet NJ out 20 nm- 1102 AM EDT Sat Jul 17 2021 This Hazardous Weather Outlook is for the Atlantic coastal waters adjacent to Atlantic County out 20 nm. .DAY ONE...Through tonight. The probability for widespread hazardous weather is low. .DAYS TWO THROUGH SEVEN...Sunday through Friday. The probability for widespread hazardous weather is low. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures. ANZ453-181502- Coastal waters from Great Egg Inlet to Cape May NJ out 20 nm- 1102 AM EDT Sat Jul 17 2021 This Hazardous Weather Outlook is for the Atlantic coastal waters adjacent to Cape May County out 20 nm. .DAY ONE...Through tonight. The probability for widespread hazardous weather is low. .DAYS TWO THROUGH SEVEN...Sunday through Friday. The probability for widespread hazardous weather is low. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures. ANZ454-181502- Coastal waters from Cape May NJ to Cape Henlopen DE out 20 nm- 1102 AM EDT Sat Jul 17 2021 This Hazardous Weather Outlook is for the Atlantic coastal waters adjacent to the mouth of Delaware Bay out 20 nm. .DAY ONE...Through tonight. The probability for widespread hazardous weather is low. .DAYS TWO THROUGH SEVEN...Sunday through Friday. The probability for widespread hazardous weather is low. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures. ANZ455-181502- Coastal waters from Cape Henlopen to Fenwick Island DE out 20 nm- 1102 AM EDT Sat Jul 17 2021 This Hazardous Weather Outlook is for the Atlantic coastal waters adjacent to Sussex County out 20 nm. .DAY ONE...Through tonight. The probability for widespread hazardous weather is low. .DAYS TWO THROUGH SEVEN...Sunday through Friday. The probability for widespread hazardous weather is low. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures.
Special Weather Statement
National Weather Service Mount Holly NJ
1255 PM EDT Sat Jul 17 2021
NJZ009-015-PAZ103>106-171745-
Hunterdon-Mercer-Lower Bucks-Upper Bucks-Eastern Montgomery-Western
Montgomery-
1255 PM EDT Sat Jul 17 2021
...A STRONG THUNDERSTORM WILL AFFECT SOUTHEASTERN HUNTERDON...
NORTHWESTERN MERCER...CENTRAL MONTGOMERY AND CENTRAL BUCKS
COUNTIES...
At 1255 PM EDT, a strong thunderstorm was located over Lumberville,
or 18 miles northwest of Trenton, moving northeast at 55 mph.
Wind gusts up to 40 mph and pea size hail are possible with this
storm.
Locations impacted include...
Lansdale, Perkasie, Doylestown, Byram, Souderton, Bedminster,
Flemington, Chalfont, Tinicum, Hatfield, New Hope, Dublin, Hopewell,
Stockton, Fricks, Lumberville, Sergeantsville, Pipersville,
Gardenville and Sand Brook.
This includes Northeast Extension between mile markers 25 and 35.
If outdoors, consider seeking shelter inside a building.
Torrential rainfall is also occurring with this storm, and may cause
localized flooding. Do not drive your vehicle through flooded
roadways.
Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.
LAT...LON 4016 7529 4029 7544 4059 7487 4047 7477
4041 7474 4040 7474
TIME...MOT...LOC 1655Z 238DEG 48KT 4039 7504
DavisThe Philadelphia radar (KDIX), 72 km away, was scanning. The volume nearest the first event began at 17:14 UTC.
21 thunderstorm wind, 2 hail, 1 funnel cloud, 1 tornado. Local standard time, as filed.
A tree was downed on NJ-29. All lanes were closed. Time estimated from radar.
Trees were reported down around Delaware Twp. Time estimated from radar.
Trees were reported down around Raritan Twp. Time estimated from radar.
Trees were reported down in Lebanon and Clinton Twps. Time estimated from radar.
Trees were reported down in Tewksbury Twp. Time estimated from radar.
Pictures and video were received of a funnel cloud and well-defined mesocyclone. No damage was reported from the area and there were no indications a tornado touchdown occurred.
A tree and wires were downed across a road in Flemington. Time estimated from radar.
A downed tree blocked a road. Time estimated from radar.
A tree and wires were downed. Time estimated from radar.
A few trees were snapped. Time estimated from radar.
A tree was blown down into a house. Time estimated from radar.
A tree was downed on I-78. Time estimated from radar.
Several large trees were downed. Time estimated from radar.
Several trees were blown down. Time estimated from radar.
Measured by cwop station ew8027.
A few trees were blown down in a Cherry Hill neighborhood.
Several large limbs were blown down. Time estimated from radar.
Numerous tree limbs were down with power outages reported in Edgewater Park. Time estimated from radar. Public report relayed by off duty NWS employee.
An mPing report of a tree or large limbs down.
Several large tree limbs were downed in Burlington.
A narrow, discontinuous, path of tree damage began just east of |the Route 206 and Columbus-Jobstown Road intersection. This is 1 |mile northeast of the Burlington County Fairgrounds. Significant |tree damage was observed in a neighborhood north of Columbus-|Jobstown Road. From there, several large limbs were snapped off on|Island Road. One tree was uprooted and one was snapped on |Juliustown-Georgetown Road. An additional tree was snapped on NJ |Route 68. Numerous large limbs were blown on powerlines on Monmouth|Road near Tilghmans Corner. Scattered tree damage was observed in|Jacobstown in North Hanover Township. The tornado dissipated |before the Ocean County line.
Several trees were downed in Evesham Twp. Time estimated from radar.
A large tree was snapped and several large limbs were downed. Time estimated from radar.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in New Jersey in 2021Every state in 2021This day in weather historyThe tornado archive for New Jersey, 2021Warnings in New Jersey, July 2021
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: 961963, 961964, 961965, 961966, 961967, 961959, 961960, 961968, 961969, 961970, 961961, 961973, 961971, 961974, 961982, 961972, 961962, 961980, 961976, 961977, 961975, 961981, 961983, 961979, 961978.