Alert archive / New Jersey / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 185, NWS Philadelphia/Mount Holly

July 17, 2021Hunterdon County, Somerset County, New Jersey

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Jul 17, 2021, 4:55 PM EDT for Hunterdon County, Somerset County, New Jersey. It was in force for 50 min. 3 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, 4:55 PM EDT (20:55 UTC)
Expired: Jul 17, 2021, 5:45 PM EDT
In force: 50 min
Issued by: NWS Philadelphia/Mount Holly
Area: Storm-based polygon
Hail: 1.0 in
Wind: 60.0 mph

Counties Hunterdon County, NJ, Somerset County, NJ

The radar

The Philadelphia radar (KDIX), 81 km from the middle of the area, began a volume at 20:56 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, 5:00 PM EDT	HAIL 0.25	Flemington, NJ
Jul 17, 5:10 PM EDT	TSTM WND DMG	Flemington, NJ	TREE AND WIRES DOWN ACROSS A ROAD IN FLEMINGTON. TIME ESTIMATED FROM RADAR.
Jul 17, 5:30 PM EDT	TSTM WND DMG	2 Ese Whitehouse Statio, NJ	TREE DOWN COMPLETELY BLOCKING THE ROAD. 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, 8.9 hours before the alert went out and 168 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.

648 
WUUS51 KPHI 172055
SVRPHI
NJC019-035-172145-
/O.NEW.KPHI.SV.W.0185.210717T2055Z-210717T2145Z/

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

The National Weather Service in Mount Holly NJ has issued a

* Severe Thunderstorm Warning for...
  Hunterdon County in northwestern New Jersey...
  Northwestern Somerset County in northern New Jersey...

* Until 545 PM EDT.

* At 455 PM EDT, a severe thunderstorm was located over
  Sergeantsville, or 18 miles northwest of Trenton, moving northeast
  at 20 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...
  Flemington, High Bridge, Clinton, Peapack And Gladstone, Glen
  Gardner, Lebanon, Califon, Far Hills, Sergeantsville, Cloverhill,
  Annandale, White House Station, Sand Brook and Bernardsville.

This includes the following highways...
 Interstate 78 in New Jersey between mile markers 13 and 30.
 Interstate 287 in New Jersey between mile markers 22 and 23.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

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

&&

LAT...LON 4038 7483 4038 7486 4037 7487 4045 7507
      4075 7493 4077 7490 4076 7484 4074 7483
      4074 7476 4072 7474 4073 7471 4070 7461
TIME...MOT...LOC 2055Z 202DEG 19KT 4045 7495 

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

JEO

2 follow-up statements

579 
WWUS51 KPHI 172116
SVSPHI

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

NJC019-035-172145-
/O.CON.KPHI.SV.W.0185.000000T0000Z-210717T2145Z/
Hunterdon NJ-Somerset NJ-
516 PM EDT Sat Jul 17 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 545 PM EDT
FOR HUNTERDON AND NORTHWESTERN SOMERSET COUNTIES...

At 516 PM EDT, a severe thunderstorm was located near Flemington, or
15 miles west of Somerville, moving north at 20 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...
Flemington, High Bridge, Clinton, Peapack And Gladstone, Glen
Gardner, Lebanon, Califon, Far Hills, Sergeantsville, Cloverhill,
Annandale, White House Station, Sand Brook and Bernardsville.

This includes the following highways...
 Interstate 78 in New Jersey between mile markers 13 and 30.
 Interstate 287 in New Jersey between mile markers 22 and 23.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

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

&&

LAT...LON 4043 7480 4042 7487 4047 7506 4075 7493
      4077 7490 4076 7484 4074 7483 4074 7476
      4072 7474 4073 7471 4070 7461
TIME...MOT...LOC 2116Z 202DEG 19KT 4055 7490 

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

JEO

387 
WWUS51 KPHI 172139 RRA
SVSPHI

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

NJC019-035-172149-
/O.EXP.KPHI.SV.W.0185.000000T0000Z-210717T2145Z/
Hunterdon NJ-Somerset NJ-
539 PM EDT Sat Jul 17 2021

...THE SEVERE THUNDERSTORM WARNING FOR HUNTERDON AND NORTHWESTERN
SOMERSET COUNTIES WILL EXPIRE AT 545 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
northern and northwestern New Jersey.

LAT...LON 4043 7480 4042 7487 4047 7506 4075 7493
      4077 7490 4076 7484 4074 7483 4074 7476
      4072 7474 4073 7471 4070 7461
TIME...MOT...LOC 2139Z 202DEG 19KT 4066 7484 

$$

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, 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 17, 7:26 PM EDT	Severe Thunderstorm Warning	PHI	Hunterdon, Mercer, Middlesex, Morris, Somerset	49 min

Nearby

Severe Thunderstorm Warnings in New Jersey, 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.