Alert archive / Pennsylvania / Severe Thunderstorm Warnings in 2020

Severe Thunderstorm Warning 215, NWS Philadelphia/Mount Holly

August 7, 2020Chester County, Pennsylvania

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Aug 7, 2020, 5:00 PM EDT for Chester County, Pennsylvania. It was in force for 60 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 7, 2020, 5:00 PM EDT (21:00 UTC)
Expired: Aug 7, 2020, 6:00 PM EDT
In force: 60 min
Issued by: NWS Philadelphia/Mount Holly
Area: Storm-based polygon
Hail: 0.75 in
Wind: 60.0 mph

County Chester County, PA

The radar

The Dover AFB radar (KDOX), 127 km from the middle of the area, began a volume at 21:00 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 7, 5:02 PM EDT	TSTM WND DMG	2 Nnw Sadsburyville, PA	DOWN TREE IN WIRES ON OLD WILMINGTON ROAD AND OAK STREET. TIME ESTIMATED FROM RADAR.
Aug 7, 5:03 PM EDT	TSTM WND DMG	Mount Vernon, PA	DOWNED TREE INTO WIRES ON PA 472 NEAR OXFORD. TIME ESTIMATED FROM RADAR.
Aug 7, 5:05 PM EDT	TSTM WND DMG	Cochranville, PA	TREE BLOWN DOWN BLOCKING SOUTHBOUND LANE AT THE INTERSECTION OF LIMESTONE RD AND GAP NEWPORT PIKE. TIME ESTIMATED FROM RADAR.
Aug 7, 5:08 PM EDT	TSTM WND DMG	1 Ne Londonderry Twp, PA	SEVERAL TREES DOWN ALONG PORTIONS OF ROUTE 41. TIME ESTIMATED FROM RADAR.
Aug 7, 5:12 PM EDT	TSTM WND DMG	1 Ssw East Brandywine T, PA	SEVERAL TREES AND POLES DOWN JUST NORTH OF FISHERVILLE ROAD. TIME ESTIMATED FROM RADAR.
Aug 7, 5:25 PM EDT	TSTM WND GST 52	2 E Londonderry Twp, PA	52 MPH WIND GUST MEASURED AT WEST GROVE DEOS (DSCR) MESONET.

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 12:00Z, 9.0 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: 301 J/kg
Mixed-layer CIN: -67 J/kg
Mixed-layer LCL: 665 m above ground
0-6 km bulk shear: 22 kt
0-1 km storm-relative helicity: -37 m²/s²
0-3 km storm-relative helicity: 18 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

455 
WUUS51 KPHI 072100
SVRPHI
PAC029-072200-
/O.NEW.KPHI.SV.W.0215.200807T2100Z-200807T2200Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Mount Holly NJ
500 PM EDT Fri Aug 7 2020

The National Weather Service in Mount Holly NJ has issued a

* Severe Thunderstorm Warning for...
  Chester County in southeastern Pennsylvania...

* Until 600 PM EDT.

* At 459 PM EDT, a severe thunderstorm was located over Parkesburg,
  or 12 miles southeast of New Holland, moving east at 15 mph.

  HAZARD...60 mph wind gusts.

  SOURCE...Radar indicated.

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

* Locations impacted include...
  West Chester, Coatesville, Downingtown, Kennett Square, Oxford,
  Parkesburg, West Grove, Honey Brook, Homeville, Glen Roy,
  Cochranville, Mount Vernon, Marshallton, Lionville-Marchwood,
  Glenmoore, Paoli, Lionville, Ladenberg, Kemblesville and North
  Star.

This includes Pennsylvania Turnpike between mile markers 307 and 323.
 
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 this storm. Move indoors
immediately. Remember, if you can hear thunder, you are close enough
to be struck by lightning.

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

&&

LAT...LON 3981 7603 3983 7604 3983 7602 3985 7602
      3987 7599 3992 7600 3994 7598 3995 7600
      4004 7593 4012 7593 4008 7545 3972 7578
      3975 7608
TIME...MOT...LOC 2059Z 279DEG 13KT 3995 7594 

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

Robertson

2 follow-up statements

187 
WWUS51 KPHI 072114
SVSPHI

Severe Weather Statement
National Weather Service Mount Holly NJ
514 PM EDT Fri Aug 7 2020

PAC029-072200-
/O.CON.KPHI.SV.W.0215.000000T0000Z-200807T2200Z/
Chester PA-
514 PM EDT Fri Aug 7 2020

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 600 PM EDT
FOR SOUTHERN CHESTER COUNTY...

At 514 PM EDT, a severe thunderstorm was located near Coatesville, or
12 miles west of West Chester, moving east at 15 mph.

HAZARD...60 mph wind gusts.

SOURCE...Radar indicated.

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

Locations impacted include...
West Chester, Coatesville, Downingtown, Kennett Square, Oxford,
Parkesburg, West Grove, Homeville, Glen Roy, Cochranville, Mount
Vernon, Marshallton, Lionville-Marchwood, Paoli, Lionville,
Ladenberg, Kemblesville, North Star, Hockessin and West Goshen.

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 this storm, and may lead to
flash flooding. Do not drive your vehicle through flooded roadways.

&&

LAT...LON 3981 7603 3983 7604 3983 7602 3985 7602
      3987 7599 3992 7600 3994 7598 3995 7600
      4001 7595 4008 7545 3972 7578 3975 7608
TIME...MOT...LOC 2114Z 277DEG 15KT 3994 7584 

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

Robertson

188 
WWUS51 KPHI 072131
SVSPHI

Severe Weather Statement
National Weather Service Mount Holly NJ
531 PM EDT Fri Aug 7 2020

PAC029-072200-
/O.CON.KPHI.SV.W.0215.000000T0000Z-200807T2200Z/
Chester PA-
531 PM EDT Fri Aug 7 2020

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 600 PM EDT
FOR SOUTHEASTERN CHESTER COUNTY...

At 531 PM EDT, a severe thunderstorm was located near Kennett Square,
or 8 miles southwest of West Chester, moving east at 20 mph.

HAZARD...60 mph wind gusts.

SOURCE...Radar indicated.

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

Locations impacted include...
West Chester, Coatesville, Downingtown, Kennett Square, West Grove,
Paoli, Marshallton, Ladenberg, Kemblesville, Lionville-Marchwood,
North Star, Hockessin, West Goshen, Malvern, South Coatesville,
Avondale, Modena, Exton, Thorndale and Chesterbrook.

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 this storm, and may lead to
flash flooding. Do not drive your vehicle through flooded roadways.

&&

LAT...LON 4000 7584 4001 7584 4008 7545 3972 7578
      3974 7594
TIME...MOT...LOC 2131Z 287DEG 19KT 3988 7574 

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

Robertson

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 7, 6:49 AM EDT	Areal Flood Advisory	PHI	Berks	4 hr
Aug 7, 9:22 AM EDT	Areal Flood Advisory	PHI	Bucks	3 hr
Aug 7, 10:34 AM EDT	Severe Thunderstorm Warning	PHI	Carbon, Lehigh	56 min
Aug 7, 11:28 AM EDT	Special Weather Statement	PHI	Carbon, Lehigh	47 min
Aug 7, 2:34 PM EDT	Areal Flood Advisory	PHI	Berks	4 hr
Aug 7, 3:46 PM EDT	Areal Flood Advisory	PHI	Carbon, Lehigh, Northampton	4 hr
Aug 7, 4:10 PM EDT	Flash Flood Warning	PHI	Berks	2 hr
Aug 7, 4:20 PM EDT	Areal Flood Advisory	PHI	Chester, Montgomery	4 hr
Aug 7, 4:32 PM EDT	Flash Flood Warning	PHI	Chester	3 hr
Aug 7, 4:47 PM EDT	Special Weather Statement	PHI	Chester	28 min
Aug 7, 5:03 PM EDT	Flash Flood Warning	PHI	Chester, Delaware	5 hr
Aug 7, 5:15 PM EDT	Areal Flood Advisory	PHI	Bucks	3 hr
Aug 7, 5:25 PM EDT	Areal Flood Advisory	PHI	Bucks, Montgomery, Philadelphia	3 hr
Aug 7, 5:38 PM EDT	Severe Thunderstorm Warning	PHI	Chester, Delaware, Montgomery, Philadelphia	52 min
Aug 7, 5:43 PM EDT	Flash Flood Warning	PHI	Montgomery, Philadelphia	4 hr
Aug 7, 5:49 PM EDT	Tornado Warning	PHI	Chester, Delaware	26 min
Aug 7, 5:57 PM EDT	Severe Thunderstorm Warning	PHI	Delaware, Philadelphia	48 min
Aug 7, 6:00 PM EDT	Tornado Warning	PHI	Delaware	30 min
Aug 7, 6:39 PM EDT	Severe Thunderstorm Warning	PHI	Bucks	27 min
Aug 7, 7:10 PM EDT	River Flood Warning	PHI	Delaware	7 hr
Aug 7, 7:17 PM EDT	Areal Flood Warning	PHI	Bucks, Montgomery	3 hr

Nearby

Severe Thunderstorm Warnings in Pennsylvania, 2020 Every 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.