Alert archive / Pennsylvania / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 247, NWS Philadelphia/Mount Holly

August 10, 2021Gloucester County, Salem County, New Jersey; Chester County, Delaware County, Montgomery County, Pennsylvania; New Castle County, Delaware

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Aug 10, 2021, 8:18 PM EDT for Gloucester County, Salem County, New Jersey; Chester County, Delaware County, Montgomery County, Pennsylvania; New Castle County, Delaware. It was in force for 42 min. 6 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 10, 2021, 8:18 PM EDT (00:18 UTC)
Expired: Aug 10, 2021, 9:00 PM EDT
In force: 42 min
Issued by: NWS Philadelphia/Mount Holly
Area: Storm-based polygon
Hail: 0.75 in
Wind: 60.0 mph

Counties New Castle County, DE, Gloucester County, NJ, Salem County, NJ, Chester County, PA, Delaware County, PA, Montgomery County, PA

The radar

The Philadelphia radar (KDIX), 95 km from the middle of the area, began a volume at 00:21 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
Aug 10, 8:20 PM EDT	TSTM WND DMG	2 E Birmingham Twp, PA	DOWNED TREE LIMBS BLOCKING BRINTONS BRIDGE RD AT DILWORTHTOWN RD. TIME ESTIMATED FROM RADAR.
Aug 10, 8:22 PM EDT	TSTM WND DMG	Malvern, PA	TREE LIMBS AND OTHER STORM DEBRIS DOWN ON LANCASTER AVE AT WOODVIEW DR. TIME ESTIMATED FROM RADAR.
Aug 10, 8:23 PM EDT	TSTM WND DMG	1 Ne Pennsville, NJ	WIRES DOWN NEAR NEW JERSEY AVE. TIME ESTIMATED FROM RADAR.
Aug 10, 8:25 PM EDT	TSTM WND DMG	Swarthmore, PA	TREE AND WIRES DOWN NEAR THE INTERSECTION OF RUTGERS AVE AT HARVARD AVE. TIME ESTIMATED FROM RADAR.
Aug 10, 8:27 PM EDT	TSTM WND DMG	1 Nne Woodlyn, PA	DOWNED TREE AND WIRES NEAR EISENHOWER AVE AT CATHERINE AVE. TIME ESTIMATED FROM RADAR.
Aug 10, 8:30 PM EDT	TSTM WND DMG	Primos, PA	TREE AND WIRES DOWN NEAR THE INTERSECTION OF BISHOP AVE AND BROADWAY AVE. 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

Washington/Dulle, VA (KIAD), launched 00:00Z, 0.3 hours before the alert went out and 191 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: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 1735 m above ground
0-6 km bulk shear: 22 kt
0-1 km storm-relative helicity: 142 m²/s²
0-3 km storm-relative helicity: 210 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

342 
WUUS51 KPHI 110018
SVRPHI
DEC003-NJC015-033-PAC029-045-091-110100-
/O.NEW.KPHI.SV.W.0247.210811T0018Z-210811T0100Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Mount Holly NJ
818 PM EDT Tue Aug 10 2021

The National Weather Service in Mount Holly NJ has issued a

* Severe Thunderstorm Warning for...
  Northeastern New Castle County in northern Delaware...
  Northwestern Salem County in southern New Jersey...
  Northwestern Gloucester County in southern New Jersey...
  South central Montgomery County in southeastern Pennsylvania...
  Southeastern Chester County in southeastern Pennsylvania...
  Delaware County in southeastern Pennsylvania...

* Until 900 PM EDT.

* At 818 PM EDT, a severe thunderstorm was located over Talleyville,
  or near Wilmington, moving east at 15 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...
  Wilmington, West Chester, Chester, Pennsville, Westtown, Carneys
  Point, Conshohocken, Swarthmore, Elsmere, New Castle, Penns Grove,
  Salem, Narberth, Alloway, Quinton, Newport, Arden, Stanton, Cheyney
  and Talleyville.

This includes the following highways...
 New Jersey Turnpike near exit 1.
 Interstate 95 in Pennsylvania between mile markers 0 and 8.
 Interstate 95 in Delaware between mile markers 6 and 23.
 Interstate 76 in Pennsylvania between mile markers 329 and 335.
 Interstate 295 in New Jersey between mile markers 0 and 13.
 Interstate 476 in Pennsylvania between mile markers 0 and 19.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4001 7563 4012 7524 3952 7540 3967 7570
TIME...MOT...LOC 0018Z 277DEG 13KT 3982 7559 

HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...0.75 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH

$$

SFJ

2 follow-up statements

811 
WWUS51 KPHI 110046
SVSPHI

Severe Weather Statement
National Weather Service Mount Holly NJ
846 PM EDT Tue Aug 10 2021

DEC003-NJC015-033-PAC029-045-091-110100-
/O.CON.KPHI.SV.W.0247.000000T0000Z-210811T0100Z/
New Castle DE-Salem NJ-Gloucester NJ-Montgomery PA-Chester PA-
Delaware PA-
846 PM EDT Tue Aug 10 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 900 PM EDT
FOR NORTHEASTERN NEW CASTLE...NORTHWESTERN SALEM...NORTHWESTERN
GLOUCESTER...SOUTH CENTRAL MONTGOMERY...SOUTHEASTERN CHESTER AND
DELAWARE COUNTIES...

At 845 PM EDT, a severe thunderstorm was located over Arden, or near
Wilmington, moving east at 15 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...
Wilmington, West Chester, Chester, Pennsville, Westtown, Carneys
Point, Conshohocken, Swarthmore, Elsmere, New Castle, Penns Grove,
Salem, Narberth, Alloway, Quinton, Newport, Arden, Stanton, Cheyney
and Talleyville.

This includes the following highways...
 New Jersey Turnpike near exit 1.
 Interstate 95 in Pennsylvania between mile markers 0 and 8.
 Interstate 95 in Delaware between mile markers 6 and 23.
 Interstate 76 in Pennsylvania between mile markers 329 and 335.
 Interstate 295 in New Jersey between mile markers 0 and 13.
 Interstate 476 in Pennsylvania between mile markers 0 and 19.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4001 7563 4012 7524 3952 7540 3967 7570
TIME...MOT...LOC 0045Z 277DEG 13KT 3981 7546 

HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...0.75 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH

$$

SFJ

015 
WWUS51 KPHI 110056
SVSPHI

Severe Weather Statement
National Weather Service Mount Holly NJ
856 PM EDT Tue Aug 10 2021

DEC003-NJC015-033-PAC029-045-091-110106-
/O.EXP.KPHI.SV.W.0247.000000T0000Z-210811T0100Z/
New Castle DE-Salem NJ-Gloucester NJ-Montgomery PA-Chester PA-
Delaware PA-
856 PM EDT Tue Aug 10 2021

...THE SEVERE THUNDERSTORM WARNING FOR NORTHEASTERN NEW CASTLE...
NORTHWESTERN SALEM...NORTHWESTERN GLOUCESTER...SOUTH CENTRAL
MONTGOMERY...SOUTHEASTERN CHESTER AND DELAWARE COUNTIES WILL EXPIRE
AT 900 PM EDT...
        
The storm which prompted the warning has moved out of the area.
Therefore, the warning will be allowed to expire.  However gusty
winds are still possible in the wake of this thunderstorm.

LAT...LON 4001 7563 4012 7524 3952 7540 3967 7570
TIME...MOT...LOC 0056Z 277DEG 13KT 3981 7542 

$$

SFJ

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 10, 8:02 PM EDT	Severe Thunderstorm Warning	PHI	Camden, Gloucester	43 min
Aug 10, 8:23 PM EDT	Special Marine Warning	PHI		79 min
Aug 10, 8:36 PM EDT	Severe Thunderstorm Warning	PHI	Atlantic, Burlington, Camden, Cumberland, Gloucester, Salem	39 min
Aug 10, 8:43 PM EDT	Areal Flood Advisory	PHI	Burlington, Camden, Gloucester	2 hr
Aug 10, 9:07 PM EDT	Special Weather Statement	PHI	Burlington, Camden, Cumberland	23 min
Aug 11, 2:56 PM EDT	Excessive Heat Watch	PHI	Hunterdon, Morris, Warren	12 hr
Aug 11, 5:57 PM EDT	Special Weather Statement	PHI	Sussex	48 min
Aug 11, 6:32 PM EDT	Special Weather Statement	PHI	Morris, Sussex, Warren	28 min
Aug 11, 6:50 PM EDT	Areal Flood Advisory	PHI	Hunterdon, Morris, Somerset, Sussex, Warren	3 hr
Aug 11, 7:04 PM EDT	Areal Flood Advisory	PHI	Gloucester, Hunterdon, Salem	2 hr
Aug 11, 7:04 PM EDT	Severe Thunderstorm Warning	PHI	Morris, Sussex, Warren	41 min
Aug 11, 7:11 PM EDT	Severe Thunderstorm Warning	PHI	Burlington, Camden, Gloucester	49 min
Aug 11, 7:28 PM EDT	Flash Flood Warning	PHI	Morris, Warren	3 hr
Aug 11, 7:45 PM EDT	Special Weather Statement	PHI	Morris	45 min
Aug 11, 7:52 PM EDT	Special Weather Statement	PHI	Atlantic, Burlington, Camden, Gloucester, Mercer	53 min
Aug 11, 7:57 PM EDT	Special Weather Statement	PHI	Hunterdon, Middlesex, Somerset	48 min
Aug 11, 4:46 PM EDT	Special Weather Statement	PHI	Monroe	44 min
Aug 11, 4:58 PM EDT	Special Weather Statement	PHI	Berks	47 min
Aug 11, 5:20 PM EDT	Areal Flood Advisory	PHI	Carbon, Monroe	57 min
Aug 11, 5:48 PM EDT	Severe Thunderstorm Warning	PHI	Berks	57 min
Aug 11, 6:16 PM EDT	Severe Thunderstorm Warning	PHI	Berks, Lehigh, Montgomery	44 min
Aug 11, 6:26 PM EDT	Severe Thunderstorm Warning	PHI	Berks, Chester, Delaware, Montgomery	49 min
Aug 11, 6:48 PM EDT	Severe Thunderstorm Warning	PHI	Bucks, Lehigh, Montgomery, Northampton	42 min
Aug 10, 8:11 PM EDT	Special Weather Statement	PHI	New Castle	34 min
Aug 10, 9:09 PM EDT	Special Weather Statement	PHI	Sussex	36 min

Nearby

Severe Thunderstorm Warnings in Pennsylvania, 2021 Severe Thunderstorm Warnings in New Jersey, 2021 Severe Thunderstorm Warnings in Delaware, 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.