Alert archive / New Jersey / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 191, NWS Philadelphia/Mount Holly

July 17, 20215 counties in New Jersey; Bucks County, Pennsylvania

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Jul 17, 2021, 7:26 PM EDT for 5 counties in New Jersey; Bucks County, Pennsylvania. It was in force for 49 min. 2 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: Jul 17, 2021, 7:26 PM EDT (23:26 UTC)
Expired: Jul 17, 2021, 8:15 PM EDT
In force: 49 min
Issued by: NWS Philadelphia/Mount Holly
Area: Storm-based polygon
Hail: 1.0 in
Wind: 60.0 mph

Counties Hunterdon County, NJ, Mercer County, NJ, Middlesex County, NJ, Morris County, NJ, Somerset County, NJ, Bucks County, PA

The radar

The Philadelphia radar (KDIX), 63 km from the middle of the area, began a volume at 23:29 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

Time	Report	Where	Remark
Jul 17, 7:30 PM EDT	TSTM WND DMG	Ringoes, NJ	REPORT OF A TREE BLOWN DOWN INTO A HOUSE. TIME ESTIMATED FROM RADAR.
Jul 17, 7:35 PM EDT	TSTM WND DMG	1 Wsw Clinton, NJ	TREE DOWN ON INTERSTATE 78. TIME ESTIMATED FROM RADAR.

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

The watch it was issued in

The SPC watch in force over the same counties when this warning went out.

Issued	Product	Office	Lasted
Jul 17, 1:13 PM EDT	Severe Thunderstorm Watch	SPC	10 hr

The nearest sounding before it

Brookhaven, NY (KOKX), launched 12:00Z, 11.4 hours before the alert went out and 166 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-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

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: 1203 J/kg
Mixed-layer CIN: -55 J/kg
Mixed-layer LCL: 1054 m above ground
0-6 km bulk shear: 24 kt
0-1 km storm-relative helicity: 35 m²/s²
0-3 km storm-relative helicity: 46 m²/s²
Significant tornado parameter: 0.2
Supercell composite: 1.0

Open this sounding in Storm Lab

The text

As transmitted.

060 
WUUS51 KPHI 172326
SVRPHI
NJC019-021-023-027-035-PAC017-180015-
/O.NEW.KPHI.SV.W.0191.210717T2326Z-210718T0015Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Mount Holly NJ
726 PM EDT Sat Jul 17 2021

The National Weather Service in Mount Holly NJ has issued a

* Severe Thunderstorm Warning for...
  Eastern Hunterdon County in northwestern New Jersey...
  Southern Morris County in northern New Jersey...
  Mercer County in central New Jersey...
  Somerset County in northern New Jersey...
  Northwestern Middlesex County in northern New Jersey...
  East central Bucks County in southeastern Pennsylvania...

* Until 815 PM EDT.

* At 725 PM EDT, a severe thunderstorm was located over Cloverhill,
  or 10 miles southwest of Somerville, moving northeast at 30 mph.

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

  SOURCE...Radar indicated.

  IMPACT...Minor damage to vehicles is possible. Wind damage to 
           roofs, siding, trees, and power lines is possible.

* Locations impacted include...
  Trenton, Somerville, Somerset, Bridgewater, South Brunswick, Ewing,
  Middlesex, Princeton, Bound Brook, Manville, Flemington, High
  Bridge, Clinton, Pennington, Peapack And Gladstone, New Hope,
  Hopewell, Lebanon, Far Hills and Rocky Hill.

This includes the following highways...
 Interstate 78 in New Jersey between mile markers 15 and 40.
 Interstate 295 in New Jersey between mile markers 65 and 76.
 Interstate 287 in New Jersey between mile markers 8 and 27.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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 this storm. Move indoors
immediately. Remember, if you can hear thunder, you are close enough
to be struck by lightning.

&&

LAT...LON 4027 7501 4068 7495 4071 7447 4054 7447
      4023 7463
TIME...MOT...LOC 2325Z 245DEG 25KT 4048 7478 

HAIL...1.00IN
WIND...60MPH
 
$$

JEO

2 follow-up statements

319 
WWUS51 KPHI 172348
SVSPHI

Severe Weather Statement
National Weather Service Mount Holly NJ
748 PM EDT Sat Jul 17 2021

NJC019-021-023-027-035-PAC017-180015-
/O.CON.KPHI.SV.W.0191.000000T0000Z-210718T0015Z/
Hunterdon NJ-Morris NJ-Mercer NJ-Somerset NJ-Middlesex NJ-Bucks PA-
748 PM EDT Sat Jul 17 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 815 PM EDT
FOR SOUTHEASTERN HUNTERDON...SOUTHERN MORRIS...MERCER...SOMERSET...
NORTHWESTERN MIDDLESEX AND EAST CENTRAL BUCKS COUNTIES...

At 748 PM EDT, a severe thunderstorm was located over Manville, or
over Somerville, moving northeast at 30 mph.

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

SOURCE...Radar indicated.

IMPACT...Minor damage to vehicles is possible. Wind damage to roofs, 
         siding, trees, and power lines is possible.

Locations impacted include...
Trenton, Somerville, Somerset, Bridgewater, South Brunswick, Ewing,
Middlesex, Princeton, Bound Brook, Manville, Flemington, Pennington,
New Hope, Hopewell, Far Hills, Rocky Hill, Stockton, Millstone,
Washington Crossing and Skillman.

This includes the following highways...
 Interstate 78 in New Jersey between mile markers 25 and 40.
 Interstate 295 in New Jersey between mile markers 65 and 76.
 Interstate 287 in New Jersey between mile markers 8 and 27.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Frequent cloud to ground lightning is occurring with this storm. Move
indoors immediately. Lightning is one of nature's leading killers.
Remember, if you can hear thunder, you are close enough to be struck
by lightning.

&&

LAT...LON 4027 7501 4040 7497 4050 7492 4057 7482
      4069 7475 4071 7447 4054 7447 4023 7463
TIME...MOT...LOC 2348Z 245DEG 25KT 4055 7459 

HAIL...1.00IN
WIND...60MPH
 
$$

JEO

232 
WWUS51 KPHI 180009
SVSPHI

Severe Weather Statement
National Weather Service Mount Holly NJ
809 PM EDT Sat Jul 17 2021

NJC019-021-023-027-035-PAC017-180019-
/O.EXP.KPHI.SV.W.0191.000000T0000Z-210718T0015Z/
Hunterdon NJ-Morris NJ-Mercer NJ-Somerset NJ-Middlesex NJ-Bucks PA-
809 PM EDT Sat Jul 17 2021

...THE SEVERE THUNDERSTORM WARNING FOR SOUTHEASTERN HUNTERDON...
SOUTHERN MORRIS...MERCER...SOMERSET...NORTHWESTERN MIDDLESEX AND EAST
CENTRAL BUCKS COUNTIES WILL EXPIRE AT 815 PM EDT...
                
The storm which prompted the warning has weakened below severe
limits, and no longer poses an immediate threat to life or property.
Therefore, the warning will be allowed to expire.  However gusty
winds are still possible with this thunderstorm.

A Severe Thunderstorm Watch remains in effect until 1100 PM EDT for
central, northern and northwestern New Jersey...and southeastern
Pennsylvania.

LAT...LON 4027 7501 4040 7497 4050 7492 4057 7482
      4069 7475 4071 7447 4054 7447 4023 7463
TIME...MOT...LOC 0009Z 245DEG 25KT 4061 7442 

$$

JEO

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 17, 12:55 PM EDT	Special Weather Statement	PHI	Hunterdon	50 min
Jul 17, 1:05 PM EDT	Severe Thunderstorm Warning	PHI	Hunterdon, Mercer	40 min
Jul 17, 1:31 PM EDT	Areal Flood Advisory	PHI	Hunterdon	97 min
Jul 17, 1:50 PM EDT	Special Marine Warning	PHI		40 min
Jul 17, 1:56 PM EDT	Severe Thunderstorm Warning	PHI	Hunterdon, Morris, Somerset, Warren	36 min
Jul 17, 2:02 PM EDT	Areal Flood Advisory	PHI	Monmouth, Ocean	92 min
Jul 17, 2:56 PM EDT	Severe Thunderstorm Warning	PHI	Middlesex, Somerset	49 min
Jul 17, 3:06 PM EDT	Severe Thunderstorm Warning	PHI	Warren	39 min
Jul 17, 3:09 PM EDT	Tornado Warning	PHI	Middlesex	21 min
Jul 17, 3:38 PM EDT	Areal Flood Advisory	PHI	Middlesex	40 min
Jul 17, 3:51 PM EDT	Severe Thunderstorm Warning	PHI	Middlesex	24 min
Jul 17, 4:55 PM EDT	Severe Thunderstorm Warning	PHI	Hunterdon, Somerset	50 min
Jul 17, 5:13 PM EDT	Areal Flood Advisory	PHI	Hunterdon	4 hr
Jul 17, 5:19 PM EDT	Tornado Warning	PHI	Hunterdon	14 min
Jul 17, 5:25 PM EDT	Flash Flood Warning	PHI	Hunterdon	6 hr
Jul 17, 5:30 PM EDT	Severe Thunderstorm Warning	PHI	Hunterdon, Warren	19 min
Jul 17, 5:52 PM EDT	Areal Flood Advisory	PHI	Somerset	2 hr
Jul 17, 6:02 PM EDT	Severe Thunderstorm Warning	PHI	Hunterdon, Mercer, Somerset	43 min
Jul 17, 6:15 PM EDT	Flash Flood Warning	PHI	Morris, Somerset	5 hr
Jul 17, 6:39 PM EDT	Severe Thunderstorm Warning	PHI	Hunterdon, Mercer, Middlesex, Morris, Somerset	51 min
Jul 17, 6:51 PM EDT	Severe Thunderstorm Warning	PHI	Burlington	39 min
Jul 17, 6:59 PM EDT	Small Craft Advisory	PHI		7 hr
Jul 17, 7:01 PM EDT	Severe Thunderstorm Warning	PHI	Hunterdon, Somerset	44 min
Jul 17, 7:12 PM EDT	Areal Flood Advisory	PHI	Mercer, Somerset	3 hr
Jul 16, 8:14 PM EDT	Special Weather Statement	PHI	Montgomery	31 min
Jul 16, 8:41 PM EDT	Special Weather Statement	PHI	Bucks	34 min
Jul 16, 9:07 PM EDT	Special Weather Statement	PHI	Lehigh	23 min
Jul 16, 9:29 PM EDT	Special Weather Statement	PHI	Lehigh	31 min
Jul 16, 10:21 PM EDT	Special Weather Statement	PHI	Lehigh	24 min
Jul 17, 2:30 PM EDT	Special Weather Statement	PHI	Berks	45 min
Jul 17, 2:36 PM EDT	Severe Thunderstorm Warning	PHI	Berks	39 min
Jul 17, 7:36 PM EDT	Special Weather Statement	PHI	Carbon	54 min

Nearby

Severe Thunderstorm Warnings in New Jersey, 2021 Severe Thunderstorm Warnings in Pennsylvania, 2021 Every severe thunderstorm warning in 2021

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.