Alert archive / Pennsylvania / Severe Thunderstorm Warnings in 2020

Severe Thunderstorm Warning 216, NWS Philadelphia/Mount Holly

August 7, 2020New Castle County, Delaware; 4 counties in Pennsylvania

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Aug 7, 2020, 5:38 PM EDT for New Castle County, Delaware; 4 counties in Pennsylvania. It was in force for 52 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: Aug 7, 2020, 5:38 PM EDT (21:38 UTC)
Expired: Aug 7, 2020, 6:30 PM EDT
In force: 52 min
Issued by: NWS Philadelphia/Mount Holly
Area: Storm-based polygon
Tornado: Possible
Hail: 1.0 in
Wind: 60.0 mph

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

The radar

The Philadelphia radar (KDIX), 100 km from the middle of the area, began a volume at 21:41 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, 5:38 PM EDT	TSTM WND DMG	Hockessin, DE	SOME TREES DOWN IN HOCKESSIN. TIME ESTIMATED FROM RADAR.
Aug 7, 5:40 PM EDT	TSTM WND DMG	1 Se West Goshen, PA	DOWNED TREE IN WIRES ON WESTTOWN THORNTON ROAD AND FIVE POINTS ROAD. TIME ESTIMATED FROM RADAR.
Aug 7, 5:40 PM EDT	TORNADO	Ashland, DE	AN EF1 TORNADO WITH WINDS TO 105 MPH TOUCHED DOWN IN ASHLAND AND TRACKED TO MONTCHANIN IN NORTHERN DELAWARE. NUMEROUS TREES WERE DOWNED, SNAPPED OR UPROOTED. A NOTED CONVERGENT PATTERN IN THE DEBRIS WAS OBSERVED IN THE TREE DAMAGE ACROSS THE WILMINGTON COUNTRY
Aug 7, 5:41 PM EDT	TSTM WND DMG	1 W Greenville, DE	SIGNIFICANT STRAIGHT-LINE WIND DAMAGE OCCURRED DUE TO A SEVERE REAR-FLANK DOWNDRAFT WITH WINDS UP TO 95 MPH. THIS OCCURRED FROM GREENVILLE TO WILMINGTON IN NORTHERN DELAWARE. QUITE A BIT OF TREE DAMAGE OCCURRED INCLUDING A TREE SNAPPED AT ITS BASE. THE SIGNIFI
Aug 7, 5:50 PM EDT	TSTM WND DMG	1 Ne Wooddale, DE	SEVERAL TREES DOWN ALONG CENTERVILLE ROAD IN WESTERN GREENVILLE. TIME ESTIMATED FROM RADAR AND NEARBY REPORTS.
Aug 7, 5:50 PM EDT	TSTM WND DMG	1 N Montchanin, DE	TREES AND WIRES DOWN ALONG MONTCHANIN RD NORTH OF WILMINTON. TIME ESTIMATED BY RADAR.
Aug 7, 5:50 PM EDT	TSTM WND DMG	Greenville, DE	TREES DOWN IN GREENVILLE. TIME ESTIMATED BY RADAR.
Aug 7, 5:50 PM EDT	TSTM WND DMG	West Haven, DE	NUMEROUS TREES DOWN OR SNAPPED WITH SOME ONTO HOMES. TIME ESTIMATED FROM RADAR.
Aug 7, 5:52 PM EDT	TSTM WND DMG	Greenville, DE	A FEW TREES SNAPPED HALFWAY UP THE TRUNK. TIME ESTIMATED FROM RADAR AND NEARBY REPORTS.
Aug 7, 5:52 PM EDT	TSTM WND DMG	Greenville Manor, DE	TREES AND POWER POLES DOWN IN GREENVILLE. TIME ESTIMATED FROM RADAR.
Aug 7, 5:55 PM EDT	TSTM WND DMG	Phillips Heights, DE	TREE DOWN ONTO POWER LINES AT WILMINGTON WASHINGTON STREET EXTENSION AND HANOVER ROAD IN NORTH WILMINGTON. TIME ESTIMATED FROM RADAR.
Aug 7, 5:55 PM EDT	TSTM WND DMG	Rock Manor, DE	LARGE TREE UPROOTED AND BLOCKING SCHOOL ROAD IN ALAPOCAS. TIME ESTIMATED FROM RADAR.
Aug 7, 5:55 PM EDT	TSTM WND DMG	Wilmington, DE	TREES DOWN OR SNAPPED ON NORTH MADISON STREET BETWEEN WEST 9TH AND WEST 10TH STREETS IN WILMINGTON. TIME ESTIMATED FROM RADAR.
Aug 7, 5:55 PM EDT	TSTM WND DMG	Wilmington, DE	SEVERAL REPORTS OF TREES DOWN IN WILMINGTON. TIME ESTIMATED FROM RADAR.
Aug 7, 5:55 PM EDT	TSTM WND GST 54	Winterthur, DE	GREENVILLE DEOS (DGRN) MEASURED A 54 MPH WIND GUST.
Aug 7, 5:57 PM EDT	TSTM WND DMG	Edgemoor Gardens, DE	TREE ONTO A HOUSE WITH PEOPLE TRAPPED IN EDGEMOOR GARDENS. POWER LINES DOWN. TIME ESTIMATED FROM RADAR.
Aug 7, 6:09 PM EDT	TSTM WND DMG	Winterthur, DE	TREES AND WIRES DOWN AT KENNETT PIKE AND OLD KENNETT ROAD.
Aug 7, 6:15 PM EDT	TSTM WND DMG	Media, PA	SEVERAL TREES DOWN ACROSS THE SOUTHERN PORTION OF DELAWARE COUNTY. 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 12:00Z, 9.6 hours before the alert went out and 189 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.

514 
WUUS51 KPHI 072138
SVRPHI
DEC003-PAC029-045-091-101-072230-
/O.NEW.KPHI.SV.W.0216.200807T2138Z-200807T2230Z/

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

The National Weather Service in Mount Holly NJ has issued a

* Severe Thunderstorm Warning for...
  Northern New Castle County in northern Delaware...
  South central Montgomery County in southeastern Pennsylvania...
  Central Chester County in southeastern Pennsylvania...
  Northwestern Philadelphia County in southeastern Pennsylvania...
  Delaware County in southeastern Pennsylvania...

* Until 630 PM EDT.

* At 538 PM EDT, a severe thunderstorm was located over Kennett
  Square, or 7 miles southwest of West Chester, moving east 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...
  Philadelphia, Wilmington, Newark, West Chester, Chester,
  Pennsville, Westtown, Carneys Point, Downingtown, Conshohocken,
  Swarthmore, Elsmere, Kennett Square, New Castle, Penns Grove,
  Narberth, West Grove, Newport, Arden and Stanton.

This includes the following highways...
 Pennsylvania Turnpike between mile markers 316 and 317.
 Interstate 95 in Pennsylvania between mile markers 0 and 4.
 Interstate 95 in Delaware between mile markers 7 and 23.
 Interstate 76 in Pennsylvania between mile markers 328 and 337.
 Interstate 476 in Pennsylvania between mile markers 2 and 17.

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.

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 4006 7566 4010 7519 3962 7556 3975 7587
TIME...MOT...LOC 2138Z 287DEG 19KT 3987 7570 

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

Robertson

1 follow-up statement

832 
WWUS51 KPHI 072214
SVSPHI

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

DEC003-PAC029-045-091-101-072230-
/O.CON.KPHI.SV.W.0216.000000T0000Z-200807T2230Z/
New Castle DE-Montgomery PA-Chester PA-Philadelphia PA-Delaware PA-
614 PM EDT Fri Aug 7 2020

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 630 PM EDT
FOR NORTHEASTERN NEW CASTLE...SOUTH CENTRAL MONTGOMERY...EAST CENTRAL
CHESTER...NORTHWESTERN PHILADELPHIA AND DELAWARE COUNTIES...

At 614 PM EDT, a severe thunderstorm was located over Arden, or near
Wilmington, moving east 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...
Philadelphia, Wilmington, Chester, Pennsville, Carneys Point,
Conshohocken, Swarthmore, Elsmere, New Castle, Penns Grove, Narberth,
Newport, Arden, Stanton, Cheyney, Talleyville, Elam, Bryn Mawr, Trout
Lake and Chelsea.

This includes the following highways...
 Interstate 95 in Pennsylvania between mile markers 0 and 3.
 Interstate 95 in Delaware between mile markers 8 and 23.
 Interstate 76 in Pennsylvania between mile markers 328 and 336.
 Interstate 476 in Pennsylvania between mile markers 2 and 17.

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.

&&

LAT...LON 4008 7544 4010 7520 3962 7556 3966 7566
      3967 7567
TIME...MOT...LOC 2214Z 287DEG 19KT 3981 7546 

TORNADO...POSSIBLE
HAIL...1.00IN
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, 5:03 PM EDT	Flash Flood Warning	PHI	New Castle	5 hr
Aug 7, 5:49 PM EDT	Tornado Warning	PHI	New Castle	26 min
Aug 7, 5:57 PM EDT	Severe Thunderstorm Warning	PHI	New Castle	48 min
Aug 7, 6:00 PM EDT	Tornado Warning	PHI	New Castle	30 min
Aug 7, 6:12 PM EDT	Severe Thunderstorm Warning	PHI	Kent, New Castle	63 min
Aug 7, 6:43 PM EDT	Areal Flood Advisory	PHI	Kent, New Castle	4 hr
Aug 7, 7:04 PM EDT	Severe Thunderstorm Warning	PHI	Kent, New Castle	41 min
Aug 7, 7:21 PM EDT	Flash Flood Warning	PHI	Kent, New Castle	5 hr
Aug 7, 7:28 PM EDT	River Flood Warning	PHI	New Castle	2 hr
Aug 7, 7:36 PM EDT	Special Weather Statement	PHI	Kent	39 min
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, 5:00 PM EDT	Severe Thunderstorm Warning	PHI	Chester	60 min
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, 5:43 PM EDT	Flash Flood Warning	PHI	Montgomery, Philadelphia	4 hr
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 Severe Thunderstorm Warnings in Delaware, 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.