Alert archive / New Jersey / Severe Thunderstorm Warnings in 2020

Severe Thunderstorm Warning 242, NWS Philadelphia/Mount Holly

August 18, 20204 counties in New Jersey; Monroe County, Northampton County, Pennsylvania

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Aug 18, 2020, 12:39 AM EDT for 4 counties in New Jersey; Monroe County, Northampton County, Pennsylvania. It was in force for 66 min. 8 reports came from inside the area while it was in force.

The area

The outline as issued, with what was reported inside it.

The facts

Issued
Aug 18, 2020, 12:39 AM EDT (04:39 UTC)
Expired
Aug 18, 2020, 1:45 AM EDT
In force
66 min
Issued by
NWS Philadelphia/Mount Holly
Area
Storm-based polygon
Hail
0.75 in
Wind
60.0 mph

Counties Hunterdon County, NJ, Morris County, NJ, Sussex County, NJ, Warren County, NJ, Monroe County, PA, Northampton County, PA

The radar

The Philadelphia radar (KDIX), 135 km from the middle of the area, began a volume at 04:40 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

What was reported inside it

TimeReportWhereRemark
Aug 18, 12:44 AM EDTTSTM WND DMG1 Nne Stormville, PADOWNED TREE BLOCKING REISH ROAD IN STROUD TOWNSHIP. TIME ESTIMATED FROM RADAR.
Aug 18, 12:48 AM EDTTSTM WND DMGAnalomink, PADOWNED TREES AND POWER LINES ON PARADISE TRAIL NEAR WOODDALE ROAD. TIME ESTIMATED FROM RADAR.
Aug 18, 12:59 AM EDTTSTM WND DMG2 N Roseto, PADOWNED TREES AND WIRES NEAR TWILIGHT TRAIL. TIME ESTIMATED FROM RADAR.
Aug 18, 1:17 AM EDTTSTM WND DMG3 Sse Upper Mount Bethe, PADOWNED TREES AND WIRES NEAR HARTZELL FERRY ROAD. TIME ESTIMATED FROM RADAR.
Aug 18, 1:27 AM EDTTSTM WND DMG2 E Hope, NJDOWNED TREES NEAR STATE PARK ROAD IN THE JENNY JUMP STATE FOREST AREA. TIME ESTIMATED FROM RADAR.
Aug 18, 1:41 AM EDTTSTM WND DMG2 S Schooleys Mountain, NJTREES AND WIRES DOWN IN WASHINGTON TWP. TIME ESTIMATED BY RADAR.
Aug 18, 1:47 AM EDTTSTM WND DMG3 Wsw Jefferson Twp, NJDOWNED TREES AND WIRES NEAR WINONA TRAIL IN WOODPORT. TIME ESTIMATED FROM RADAR.
Aug 18, 1:53 AM EDTTSTM WND DMGSchooleys Mountain, NJDOWNED POWER LINES NEAR ROUTE 24 IN SCHOOLEYS MOUNTAIN. TIME ESTIMATED FROM RADAR.

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

The nearest sounding before it

Brookhaven, NY (KOKX), launched 00:00Z, 4.7 hours before the alert went out and 178 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.

Skew-T log-pSkew-T log-p diagram, Brookhaven, NY at 00:00Z on 2020-08-18Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 116 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Brookhaven, NY at 00:00Z on 2020-08-18The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 64 square meters per square second.19395878Sfc1 km3 km6 km9 kmRMLM
The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.
Mixed-layer CAPE
116 J/kg
Mixed-layer CIN
-68 J/kg
Mixed-layer LCL
878 m above ground
0-6 km bulk shear
31 kt
0-1 km storm-relative helicity
64 m²/s²
0-3 km storm-relative helicity
88 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

387 
WUUS51 KPHI 180439
SVRPHI
NJC019-027-037-041-PAC089-095-180545-
/O.NEW.KPHI.SV.W.0242.200818T0439Z-200818T0545Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Mount Holly NJ
1239 AM EDT Tue Aug 18 2020

The National Weather Service in Mount Holly NJ has issued a

* Severe Thunderstorm Warning for...
  Western Morris County in northern New Jersey...
  Northeastern Hunterdon County in northwestern New Jersey...
  Sussex County in northwestern New Jersey...
  Warren County in northwestern New Jersey...
  Monroe County in northeastern Pennsylvania...
  Northeastern Northampton County in eastern Pennsylvania...

* Until 145 AM EDT.

* At 1238 AM EDT, severe thunderstorms were located along a line
  extending from near Skytop to near Reeders to near Rossland, moving
  east at 30 mph.

  HAZARD...60 mph wind gusts and penny size hail.

  SOURCE...Radar indicated.

  IMPACT...Damage to roofs, siding, trees, and power lines is 
           possible.

* Locations impacted include...
  Newton, Mount Pocono, Hopatcong, East Stroudsburg, Hackettstown,
  Washington, Blairstown, Bangor, Mount Arlington, Franklin, High
  Bridge, Stanhope, Pen Argyl, Hamburg, Netcong, Wind Gap, Clinton,
  Belvidere, Harmony and Oxford.

This includes the following highways...
 Interstate 78 in New Jersey between mile markers 15 and 22.
 Interstate 80 in Pennsylvania between mile markers 296 and 314.
 Interstate 80 in New Jersey between mile markers 0 and 30.
 Interstate 380 in Pennsylvania between mile markers 0 and 5.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Protecting yourself from immediate threats to life and safety shall
take priority.  Whenever possible, as long as it does not cause
greater harm, all COVID-19 protective action guidance should be
followed.

For your protection move to an interior room on the lowest floor of a
building.

In addition to large hail and damaging winds, frequent cloud to
ground lightning is occurring with these storms. Move indoors
immediately. Remember, if you can hear thunder, you are close enough
to be struck by lightning.

Torrential rainfall is occurring with these storms, and may lead to
flash flooding. Do not drive your vehicle through flooded roadways.

&&

LAT...LON 4120 7449 4086 7466 4059 7485 4089 7552
      4124 7536 4125 7513 4115 7515 4114 7509
      4108 7503 4109 7500 4116 7490 4126 7485
TIME...MOT...LOC 0438Z 289DEG 26KT 4123 7518 4100 7529 4085 7537 

HAIL...0.75IN
WIND...60MPH
 
$$

Robertson
3 follow-up statements
822 
WWUS51 KPHI 180502
SVSPHI

Severe Weather Statement
National Weather Service Mount Holly NJ
102 AM EDT Tue Aug 18 2020

NJC019-027-037-041-PAC089-095-180545-
/O.CON.KPHI.SV.W.0242.000000T0000Z-200818T0545Z/
Morris NJ-Hunterdon NJ-Sussex NJ-Warren NJ-Monroe PA-Northampton PA-
102 AM EDT Tue Aug 18 2020

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 145 AM EDT
FOR WESTERN MORRIS...NORTHEASTERN HUNTERDON...SUSSEX...WARREN...
MONROE AND NORTHEASTERN NORTHAMPTON COUNTIES...

At 102 AM EDT, severe thunderstorms were located along a line
extending from Bushkill to near Columbia to near Belfast, moving east
at 30 mph.

HAZARD...60 mph wind gusts and penny size hail.

SOURCE...Radar indicated.

IMPACT...Damage to roofs, siding, trees, and power lines is 
         possible.

Locations impacted include...
Newton, Mount Pocono, Hopatcong, East Stroudsburg, Hackettstown,
Washington, Blairstown, Bangor, Mount Arlington, Franklin, High
Bridge, Stanhope, Pen Argyl, Hamburg, Netcong, Wind Gap, Clinton,
Belvidere, Harmony and Oxford.

This includes the following highways...
 Interstate 78 in New Jersey between mile markers 15 and 22.
 Interstate 80 in Pennsylvania between mile markers 296 and 314.
 Interstate 80 in New Jersey between mile markers 0 and 30.
 Interstate 380 in Pennsylvania between mile markers 0 and 5.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Protecting yourself from immediate threats to life and safety shall
take priority.  Whenever possible, as long as it does not cause
greater harm, all COVID-19 protective action guidance should be
followed.

Remain alert for a possible tornado! Tornadoes can develop quickly
from severe thunderstorms. If you spot a tornado go at once into the
basement or small central room in a sturdy structure.

For your protection move to an interior room on the lowest floor of a
building.

Torrential rainfall is occurring with these storms, and may lead to
flash flooding. Do not drive your vehicle through flooded roadways.

&&

LAT...LON 4120 7449 4086 7466 4059 7485 4089 7552
      4124 7536 4125 7513 4115 7515 4114 7509
      4108 7503 4109 7500 4116 7490 4126 7485
TIME...MOT...LOC 0502Z 289DEG 24KT 4112 7500 4095 7511 4078 7532 

TORNADO...POSSIBLE
HAIL...0.75IN
WIND...60MPH
 
$$

Robertson
067 
WWUS51 KPHI 180509
SVSPHI

Severe Weather Statement
National Weather Service Mount Holly NJ
109 AM EDT Tue Aug 18 2020

NJC019-027-037-041-PAC089-095-180545-
/O.CON.KPHI.SV.W.0242.000000T0000Z-200818T0545Z/
Morris NJ-Hunterdon NJ-Sussex NJ-Warren NJ-Monroe PA-Northampton PA-
109 AM EDT Tue Aug 18 2020

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 145 AM EDT
FOR WESTERN MORRIS...NORTHEASTERN HUNTERDON...SUSSEX...WARREN...
SOUTHEASTERN MONROE AND NORTHEASTERN NORTHAMPTON COUNTIES...

At 109 AM EDT, severe thunderstorms were located along a line
extending from Flatbrookville to near Columbia to Belfast, moving
east at 30 mph.

HAZARD...60 mph wind gusts and penny size hail.

SOURCE...Radar indicated.

IMPACT...Damage to roofs, siding, trees, and power lines is 
         possible.

Locations impacted include...
Newton, Hopatcong, Hackettstown, Washington, Blairstown, Bangor,
Mount Arlington, Franklin, High Bridge, Stanhope, Pen Argyl, Hamburg,
Netcong, Wind Gap, Clinton, Belvidere, Harmony, Oxford, Ogdensburg
and Sussex.

This includes the following highways...
 Interstate 78 in New Jersey between mile markers 15 and 22.
 Interstate 80 in Pennsylvania near mile marker 314.
 Interstate 80 in New Jersey between mile markers 0 and 30.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Protecting yourself from immediate threats to life and safety shall
take priority.  Whenever possible, as long as it does not cause
greater harm, all COVID-19 protective action guidance should be
followed.

Remain alert for a possible tornado! Tornadoes can develop quickly
from severe thunderstorms. If you spot a tornado go at once into the
basement or small central room in a sturdy structure.

For your protection move to an interior room on the lowest floor of a
building.

Torrential rainfall is occurring with these storms, and may lead to
flash flooding. Do not drive your vehicle through flooded roadways.

&&

LAT...LON 4084 7540 4098 7515 4115 7512 4114 7509
      4108 7503 4109 7500 4116 7490 4126 7485
      4120 7449 4086 7466 4059 7485
TIME...MOT...LOC 0509Z 288DEG 26KT 4111 7494 4094 7505 4079 7524 

TORNADO...POSSIBLE
HAIL...0.75IN
WIND...60MPH
 
$$

Staarmann
966 
WWUS51 KPHI 180535
SVSPHI

Severe Weather Statement
National Weather Service Mount Holly NJ
135 AM EDT Tue Aug 18 2020

PAC089-095-180545-
/O.CAN.KPHI.SV.W.0242.000000T0000Z-200818T0545Z/
Monroe PA-Northampton PA-
135 AM EDT Tue Aug 18 2020

...THE SEVERE THUNDERSTORM WARNING FOR SOUTHEASTERN MONROE AND
NORTHEASTERN NORTHAMPTON COUNTIES IS CANCELLED...

The storms which prompted the warning have moved out of the warned 
area. Therefore, the warning has been cancelled.

LAT...LON 4118 7450 4086 7466 4059 7485 4074 7518
      4080 7510 4084 7508 4100 7491 4113 7486
TIME...MOT...LOC 0535Z 288DEG 26KT 4105 7467 4088 7482 4073 7501 

$$

NJC019-027-037-041-180545-
/O.CON.KPHI.SV.W.0242.000000T0000Z-200818T0545Z/
Morris NJ-Hunterdon NJ-Sussex NJ-Warren NJ-
135 AM EDT Tue Aug 18 2020

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 145 AM EDT
FOR WESTERN MORRIS...NORTHEASTERN HUNTERDON...SOUTHERN SUSSEX AND
WARREN COUNTIES...

At 135 AM EDT, severe thunderstorms were located along a line
extending from near Lake Mohawk to Hackettstown to Pleasant Valley,
moving east at 30 mph.

HAZARD...60 mph wind gusts and penny size hail.

SOURCE...Radar indicated.

IMPACT...Damage to roofs, siding, trees, and power lines is 
         possible.

Locations impacted include...
Newton, Hopatcong, Hackettstown, Washington, Mount Arlington,
Franklin, High Bridge, Stanhope, Hamburg, Netcong, Clinton,
Belvidere, Harmony, Oxford, Ogdensburg, Hope, Glen Gardner, Hampton,
Lebanon and Califon.

This includes the following highways...
 Interstate 78 in New Jersey between mile markers 15 and 22.
 Interstate 80 in New Jersey between mile markers 11 and 30.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Protecting yourself from immediate threats to life and safety shall
take priority.  Whenever possible, as long as it does not cause
greater harm, all COVID-19 protective action guidance should be
followed.

Remain alert for a possible tornado! Tornadoes can develop quickly
from severe thunderstorms. If you spot a tornado go at once into the
basement or small central room in a sturdy structure.

For your protection move to an interior room on the lowest floor of a
building.

Torrential rainfall is occurring with these storms, and may lead to
flash flooding. Do not drive your vehicle through flooded roadways.

&&

LAT...LON 4118 7450 4086 7466 4059 7485 4074 7518
      4080 7510 4084 7508 4100 7491 4113 7486
TIME...MOT...LOC 0535Z 288DEG 26KT 4105 7467 4088 7482 4073 7501 

TORNADO...POSSIBLE
HAIL...0.75IN
WIND...60MPH
 
$$

Staarmann

The office that day

Everything else NWS Philadelphia/Mount Holly issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Aug 17, 11:51 PM EDTCoastal Flood StatementPHIOcean4 hr
Aug 18, 12:31 AM EDTTornado WarningPHIWarren29 min
Aug 18, 12:58 AM EDTSpecial Weather StatementPHIHunterdon47 min
Aug 18, 1:13 AM EDTAreal Flood AdvisoryPHIHunterdon, Middlesex, Morris, Somerset, Sussex, Warren2 hr
Aug 18, 1:38 AM EDTSevere Thunderstorm WarningPHIHunterdon, Middlesex, Morris, Somerset, Sussex, Warren37 min
Aug 18, 2:15 AM EDTSpecial Weather StatementPHIHunterdon, Morris, Somerset30 min
Aug 17, 11:26 PM EDTSpecial Weather StatementPHIMonroe49 min
Aug 17, 11:59 PM EDTSevere Thunderstorm WarningPHICarbon, Monroe46 min

Nearby

Severe Thunderstorm Warnings in New Jersey, 2020Severe Thunderstorm Warnings in Pennsylvania, 2020Every severe thunderstorm warning in 2020

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.