Alert archive / Pennsylvania / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 97, NWS Philadelphia/Mount Holly

June 21, 2021Chester County, Delaware County, Pennsylvania; New Castle County, Delaware

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Jun 21, 2021, 6:21 PM EDT for Chester County, Delaware County, Pennsylvania; New Castle County, Delaware. It was in force for 54 min. 18 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: Jun 21, 2021, 6:21 PM EDT (22:21 UTC)
Expired: Jun 21, 2021, 7:15 PM EDT
In force: 54 min
Issued by: NWS Philadelphia/Mount Holly
Area: Storm-based polygon
Hail: 0.75 in
Wind: 60.0 mph

Counties New Castle County, DE, Chester County, PA, Delaware County, PA

The radar

The Dover AFB radar (KDOX), 118 km from the middle of the area, began a volume at 22:23 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
Jun 21, 6:41 PM EDT	TSTM WND DMG	2 Sse Parkesburg, PA	DOWNED TREE ON LIMESTONE ROAD. TIME ESTIMATED FROM RADAR.
Jun 21, 6:45 PM EDT	TSTM WND DMG	2 Nw Sadsburyville, PA	TREE AND WIRES DOWN.
Jun 21, 6:54 PM EDT	TSTM WND DMG	1 Sse Toughkenamon, PA	A FEW REPORTS OF TREES AND WIRES DOWN IN NEW GARDEN TOWNSHIP.
Jun 21, 6:54 PM EDT	TSTM WND DMG	Toughkenamon, PA	DOWNED TREE ON NEWARK ROAD. TIME ESTIMATED FROM RADAR.
Jun 21, 6:58 PM EDT	TSTM WND DMG	1 Se Kennett Square, PA	DOWNED TREES ON CREEK ROAD. TIME ESTIMATED FROM RADAR.
Jun 21, 6:58 PM EDT	TSTM WND DMG	1 Wsw Uwchlan Twp, PA	DOWNED TREE AND WIRES AND A DOWNED POWER POLE ON A RESIDENCE NEAR FORGE LANE. TIME ESTIMATED FROM RADAR.
Jun 21, 6:58 PM EDT	TSTM WND DMG	2 Se Exton, PA	DOWNED TREE ON BOOT ROAD. TIME ESTIMATED FROM RADAR.
Jun 21, 7:00 PM EDT	TSTM WND DMG	1 Ene Hockessin, DE	SEVERAL REPORTS OF DOWNED TREE LIMBS AND POWER LINES IN THE AREA. TIME ESTIMATED FROM RADAR.
Jun 21, 7:00 PM EDT	TSTM WND DMG	1 N Pike Creek, DE	DOWNED TREES AND WIRES NEAR NEW GRANVILLE ROAD AND OCHLETREE LANE. TIME ESTIMATED FROM RADAR.
Jun 21, 7:00 PM EDT	TSTM WND DMG	East Brandywine Twp, PA	MULTIPLE REPORTS OF TREES AND WIRES DOWN IN EAST BRANDYWINE TOWNSHIP.
Jun 21, 7:02 PM EDT	TSTM WND DMG	2 E Warwick Twp, PA	OUTFLOW WINDS DOWNED TREES AND WIRES NEAR HILL ROAD. TIME ESTIMATED FROM RADAR.
Jun 21, 7:02 PM EDT	TSTM WND DMG	Caln Twp, PA	DOWNED TREE LIMBS ON EDGE LANE. TIME ESTIMATED FROM RADAR.
Jun 21, 7:07 PM EDT	TSTM WND DMG	East Whiteland Twp, PA	DOWNED TREE ON MILL LANE. TIME ESTIMATED FROM RADAR.
Jun 21, 7:07 PM EDT	TSTM WND GST 56	New Castle County Airpo, DE
Jun 21, 7:13 PM EDT	TSTM WND DMG	1 N Paoli, PA	DOWNED TREE ON VALLEY ROAD. TIME ESTIMATED FROM RADAR.
Jun 21, 7:13 PM EDT	TSTM WND DMG	2 Nne Willistown Twp, PA	DOWNED TREE ON GOSHEN ROAD. TIME ESTIMATED FROM RADAR.
Jun 21, 7:15 PM EDT	TSTM WND DMG	Glendale, DE	SEVERAL REPORTS OF DOWNED TREE LIMBS AND POWER LINES IN THE AREA. TIME ESTIMATED FROM RADAR.
Jun 21, 7:17 PM EDT	TSTM WND DMG	1 Wsw Nottingham Manor, DE	REPORT OF A TREE DOWN ON A HOUSE ON SQUIRREL LANE IN NEWARK. 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
Jun 21, 4:33 PM EDT	Severe Thunderstorm Watch	SPC	6 hr

The nearest sounding before it

Washington/Dulle, VA (KIAD), launched 12:00Z, 10.4 hours before the alert went out and 163 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: 329 J/kg
Mixed-layer CIN: -164 J/kg
Mixed-layer LCL: 801 m above ground
0-6 km bulk shear: 11 kt
0-1 km storm-relative helicity: 33 m²/s²
0-3 km storm-relative helicity: 40 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

873 
WUUS51 KPHI 212221
SVRPHI
DEC003-PAC029-045-212315-
/O.NEW.KPHI.SV.W.0097.210621T2221Z-210621T2315Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Mount Holly NJ
621 PM EDT Mon Jun 21 2021

The National Weather Service in Mount Holly NJ has issued a

* Severe Thunderstorm Warning for...
  Northern New Castle County in northern Delaware...
  Chester County in southeastern Pennsylvania...
  Southwestern Delaware County in southeastern Pennsylvania...

* Until 715 PM EDT.

* At 619 PM EDT, a severe thunderstorm was located near Wakefield, 
  moving east at 35 mph.

  HAZARD...60 mph wind gusts.

  SOURCE...Radar indicated.

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

* Locations impacted include...
  Wilmington, Newark, West Chester, Coatesville, Westtown,
  Downingtown, Elsmere, Kennett Square, New Castle, Oxford,
  Parkesburg, West Grove, Honey Brook, Elverson, Newport, Arden, Glen
  Roy, Stanton, Cheyney and Glasgow.

This includes the following highways...
 Pennsylvania Turnpike between mile markers 301 and 321.
 Interstate 95 in Pennsylvania between mile markers 0 and 2.
 Interstate 95 in Delaware between mile markers 0 and 23.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3974 7612 3973 7610 3976 7606 3982 7604
      3983 7601 3987 7598 3995 7599 4004 7593
      4011 7593 4023 7569 4005 7546 3981 7541
      3971 7550 3954 7576 3958 7579 3972 7579
      3972 7613
TIME...MOT...LOC 2219Z 259DEG 30KT 3983 7621 

HAIL...<.75IN
WIND...60MPH
 
$$

NC

1 follow-up statement

722 
WWUS51 KPHI 212259
SVSPHI

Severe Weather Statement
National Weather Service Mount Holly NJ
659 PM EDT Mon Jun 21 2021

DEC003-PAC029-045-212315-
/O.CON.KPHI.SV.W.0097.000000T0000Z-210621T2315Z/
New Castle DE-Chester PA-Delaware PA-
659 PM EDT Mon Jun 21 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 715 PM EDT
FOR NORTHERN NEW CASTLE...CHESTER AND SOUTHWESTERN DELAWARE
COUNTIES...

At 658 PM EDT, a severe thunderstorm was located near Kennett Square,
or 8 miles southwest of West Chester, moving east at 40 mph.

HAZARD...60 mph wind gusts.

SOURCE...Radar indicated.

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

Locations impacted include...
Wilmington, Newark, West Chester, Coatesville, Westtown, Downingtown,
Elsmere, Kennett Square, New Castle, Oxford, Parkesburg, West Grove,
Newport, Arden, Glen Roy, Stanton, Cheyney, Talleyville, Elam and
Mount Vernon.

This includes the following highways...
 Interstate 95 in Pennsylvania between mile markers 0 and 2.
 Interstate 95 in Delaware between mile markers 1 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 3976 7606 3982 7603 3983 7601 3986 7598
      3994 7599 4001 7595 4007 7548 4006 7547
      3981 7541 3972 7549 3967 7556 3964 7579
      3972 7579 3972 7613
TIME...MOT...LOC 2258Z 258DEG 35KT 3990 7574 

HAIL...<.75IN
WIND...60MPH
 
$$

Fitzsimmons

The office that day

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

Issued	Product	Office	Counties	Lasted
Jun 20, 9:27 PM EDT	Special Weather Statement	PHI	Schuylkill	33 min
Jun 20, 9:55 PM EDT	Special Weather Statement	PHI	Lebanon	35 min
Jun 20, 10:04 PM EDT	Areal Flood Advisory	PHI	Berks	86 min
Jun 20, 10:27 PM EDT	Special Weather Statement	PHI	Berks	33 min
Jun 21, 4:35 AM EDT	Heat Advisory	PHI	Bucks, Chester, Delaware, Montgomery, Philadelphia	15 hr
Jun 21, 6:08 PM EDT	Severe Thunderstorm Warning	PHI	Berks, Lehigh	52 min
Jun 21, 7:02 PM EDT	Severe Thunderstorm Warning	PHI	Berks, Carbon, Lehigh, Northampton	43 min
Jun 21, 7:12 PM EDT	Severe Thunderstorm Warning	PHI	Chester, Delaware, Montgomery, Philadelphia	48 min
Jun 21, 7:38 PM EDT	Severe Thunderstorm Warning	PHI	Carbon, Lehigh, Monroe, Northampton	52 min
Jun 21, 6:47 PM EDT	Severe Thunderstorm Warning	PHI	Kent, New Castle	58 min
Jun 21, 7:43 PM EDT	Severe Thunderstorm Warning	PHI	Kent, New Castle, Sussex	47 min

Nearby

Severe Thunderstorm Warnings in Pennsylvania, 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.