Alert archive / Pennsylvania / Severe Thunderstorm Warnings in 2020

Severe Thunderstorm Warning 118, NWS Philadelphia/Mount Holly

July 6, 20204 counties in Pennsylvania

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Jul 6, 2020, 3:11 PM EDT for 4 counties in Pennsylvania. It was in force for 49 min. 9 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 6, 2020, 3:11 PM EDT (19:11 UTC)
Expired
Jul 6, 2020, 4:00 PM EDT
In force
49 min
Issued by
NWS Philadelphia/Mount Holly
Area
Storm-based polygon
Hail
1.0 in
Wind
60.0 mph

Counties Chester County, PA, Delaware County, PA, Montgomery County, PA, Philadelphia County, PA

The radar

The Philadelphia radar (KDIX), 89 km from the middle of the area, began a volume at 19:13 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

TimeReportWhereRemark
Jul 6, 3:15 PM EDTHAIL 11 N Oaks, PAMULTIPLE REPORTS OF HAIL NEAR COLLEGEVILLE, WITH A PHOTO OF HAIL UP TO QUARTER SIZE.
Jul 6, 3:15 PM EDTHAIL 1.25Phoenixville, PAREPORT VIA SOCIAL MEDIA WITH PHOTOS OF HAIL A LITTLE LARGER THAN QUARTER SIZE.
Jul 6, 3:29 PM EDTTSTM WND DMG1 Ssw Spring City, PASEVERAL REPORTS OF TREES AND WIRES DOWN IN SPRING CITY, ROYERSFORD, PHOENIXVILLE, AND UPPER PROVIDENCE TWP. TIME ESTIMATED FROM RADAR.
Jul 6, 3:30 PM EDTTSTM WND DMGLower Providence Townsh, PATREE DOWN ON WIRES ON PAWLINGS ROAD. TIME ESTIMATED FROM RADAR.
Jul 6, 3:30 PM EDTHAIL 1.251 E Oaks, PAREPORT VIA SOCIAL MEDIA WITH PHOTOS AND VIDEO OF HAIL UP TO ABOUT HALF DOLLAR SIZE NEAR AUDUBON. TIME ESTIMATED FROM RADAR.
Jul 6, 3:37 PM EDTTSTM WND DMG1 Wsw Valley Forge, PASEVERAL REPORTS OF TREES AND WIRES DOWN IN THE VALLEY FORGE AREA, INCLUDING NEAR OAKWOOD LANE, VALLEY PARK ROAD, JUG HOLLOW ROAD, AND DAVIS ROAD. TIME ESTIMATED FROM RADAR.
Jul 6, 3:37 PM EDTTSTM WND DMG1 Wsw Valley Forge, PASEVERAL REPORTS OF TREES AND WIRES DOWN IN VICINITY OF OAKWOOD LANE, DAVIS ROAD, JUG HOLLOW ROAD, AND VALLEY PARK ROAD. TIME ESTIMATED FROM RADAR.
Jul 6, 3:58 PM EDTTSTM WND DMG1 Ese Devault, PADOWNED TREE ON COOL VALLEY ROAD NEAR SHADOW OAK DRIVE IN DEVAULT. TIME ESTIMATED FROM RADAR.
Jul 6, 4:06 PM EDTTSTM WND DMGValley Forge, PATREE DOWN NEAR RICHARDS ROAD AND STEPHENS DRIVE, BLOCKING RICHARDS ROAD NEAR VALLEY FORGE. 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.

IssuedProductOfficeLasted
Jul 6, 1:38 PM EDTSevere Thunderstorm WatchSPC9 hr

The nearest sounding before it

Washington/Dulle, VA (KIAD), launched 12:00Z, 7.2 hours before the alert went out and 209 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-pSkew-T log-p diagram, Washington/Dulle, VA at 12:00Z on 2020-07-06Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1250 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Washington/Dulle, VA at 12:00Z on 2020-07-06The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 62 square meters per square second.1939Sfc1 km3 km6 km9 kmRMLM
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
1250 J/kg
Mixed-layer CIN
-133 J/kg
Mixed-layer LCL
1150 m above ground
0-6 km bulk shear
21 kt
0-1 km storm-relative helicity
62 m²/s²
0-3 km storm-relative helicity
57 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

588 
WUUS51 KPHI 061911
SVRPHI
PAC029-045-091-101-062000-
/O.NEW.KPHI.SV.W.0118.200706T1911Z-200706T2000Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Mount Holly NJ
311 PM EDT Mon Jul 6 2020

The National Weather Service in Mount Holly NJ has issued a

* Severe Thunderstorm Warning for...
  Southwestern Montgomery County in southeastern Pennsylvania...
  Northeastern Chester County in southeastern Pennsylvania...
  West central Philadelphia County in southeastern Pennsylvania...
  Northeastern Delaware County in southeastern Pennsylvania...

* Until 400 PM EDT.

* At 310 PM EDT, severe thunderstorms were located along a line
  extending from Phoenixville to Plymouth Meeting, moving south at 5
  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, Norristown, Phoenixville, West Norriton, East
  Norriton, Conshohocken, Collegeville, Royersford, Narberth, Trappe,
  Bryn Mawr, Trout Lake, Radnor Township, Valley Forge, Plymouth
  Meeting, Paoli, King Of Prussia, Bridgeport, Spring City and
  Malvern.

This includes the following highways...
 Pennsylvania Turnpike between mile markers 317 and 335.
 Northeast Extension between mile markers 21 and 26.
 Interstate 76 in Pennsylvania between mile markers 327 and 337.
 Interstate 476 in Pennsylvania between mile markers 10 and 19.

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 these storms. Move indoors
immediately. Remember, if you can hear thunder, you are close enough
to be struck by lightning.

&&

LAT...LON 3998 7558 4000 7523 4020 7525 4019 7559
TIME...MOT...LOC 1910Z 341DEG 5KT 4011 7552 4011 7525 

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

Robertson
1 follow-up statement
780 
WWUS51 KPHI 061934
SVSPHI

Severe Weather Statement
National Weather Service Mount Holly NJ
334 PM EDT Mon Jul 6 2020

PAC029-045-091-101-062000-
/O.CON.KPHI.SV.W.0118.000000T0000Z-200706T2000Z/
Montgomery PA-Chester PA-Philadelphia PA-Delaware PA-
334 PM EDT Mon Jul 6 2020

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 400 PM EDT
FOR SOUTHWESTERN MONTGOMERY...NORTHEASTERN CHESTER...WEST CENTRAL
PHILADELPHIA AND NORTHEASTERN DELAWARE COUNTIES...

At 334 PM EDT, severe thunderstorms were located along a line
extending from near Royersford to Conshohocken, and are nearly
stationary.
 
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, Norristown, Phoenixville, West Norriton, East Norriton,
Conshohocken, Collegeville, Royersford, Narberth, Trappe, Bryn Mawr,
Trout Lake, Radnor Township, Valley Forge, Plymouth Meeting, Paoli,
King Of Prussia, Bridgeport, Spring City and Malvern.

This includes the following highways...
 Pennsylvania Turnpike between mile markers 317 and 335.
 Northeast Extension between mile markers 21 and 26.
 Interstate 76 in Pennsylvania between mile markers 327 and 337.
 Interstate 476 in Pennsylvania between mile markers 10 and 19.

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.

Frequent cloud to ground lightning is occurring with these storms.
Move indoors immediately. Lightning is one of nature's leading
killers. Remember, if you can hear thunder, you are close enough to
be struck by lightning.

&&

LAT...LON 3998 7552 4000 7558 4019 7559 4020 7531
      4019 7525 4000 7523
TIME...MOT...LOC 1934Z 328DEG 3KT 4017 7557 4007 7531 

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

Robertson

The office that day

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

IssuedProductOfficeCountiesLasted
Jul 6, 3:16 AM EDTHeat AdvisoryPHIBucks, Chester, Delaware, Montgomery, Philadelphia12 hr
Jul 6, 12:34 PM EDTSpecial Weather StatementPHIPhiladelphia26 min
Jul 6, 12:45 PM EDTSevere Thunderstorm WarningPHIBucks, Montgomery, Philadelphia60 min
Jul 6, 12:52 PM EDTFlash Flood WatchPHIBucks, Chester, Delaware, Montgomery, Philadelphia8 hr
Jul 6, 12:57 PM EDTAreal Flood AdvisoryPHIBucks, Delaware, Montgomery, Philadelphia2 hr
Jul 6, 1:08 PM EDTFlash Flood WarningPHIBucks, Delaware, Montgomery, Philadelphia4 hr
Jul 6, 1:15 PM EDTSevere Thunderstorm WarningPHIBucks60 min
Jul 6, 1:20 PM EDTSpecial Weather StatementPHIMontgomery25 min
Jul 6, 1:24 PM EDTSpecial Weather StatementPHIMonroe36 min
Jul 6, 1:43 PM EDTSevere Thunderstorm WarningPHIBucks, Montgomery, Philadelphia62 min
Jul 6, 1:44 PM EDTSpecial Weather StatementPHIMontgomery31 min
Jul 6, 1:50 PM EDTAreal Flood AdvisoryPHIBerks, Chester, Montgomery4 hr
Jul 6, 1:50 PM EDTSevere Thunderstorm WarningPHIMonroe40 min
Jul 6, 2:02 PM EDTAreal Flood AdvisoryPHIBucks118 min
Jul 6, 2:04 PM EDTSevere Thunderstorm WarningPHIBucks, Montgomery41 min
Jul 6, 2:10 PM EDTAreal Flood AdvisoryPHIMonroe2 hr
Jul 6, 2:18 PM EDTSpecial Weather StatementPHIMontgomery27 min
Jul 6, 2:27 PM EDTSevere Thunderstorm WarningPHIMontgomery48 min
Jul 6, 2:28 PM EDTSevere Thunderstorm WarningPHIMonroe28 min
Jul 6, 2:39 PM EDTAreal Flood AdvisoryPHIBucks, Chester, Montgomery4 hr
Jul 6, 2:39 PM EDTSevere Thunderstorm WarningPHIBucks, Montgomery, Philadelphia66 min
Jul 6, 2:41 PM EDTSevere Thunderstorm WarningPHIBucks, Montgomery49 min
Jul 6, 2:48 PM EDTAreal Flood AdvisoryPHIPhiladelphia4 hr
Jul 6, 2:51 PM EDTSevere Thunderstorm WarningPHIChester, Delaware, Montgomery24 min
Jul 6, 2:57 PM EDTFlash Flood Warning EmergencyCatastrophic damage threatPHIBucks, Delaware, Montgomery, Philadelphia4 hr
Jul 6, 3:00 PM EDTSevere Thunderstorm WarningPHIBucks, Northampton45 min
Jul 6, 3:38 PM EDTSevere Thunderstorm WarningPHIBucks, Lehigh, Northampton52 min
Jul 6, 3:52 PM EDTSevere Thunderstorm WarningPHIChester, Delaware, Montgomery, Philadelphia38 min
Jul 6, 3:56 PM EDTSevere Thunderstorm WarningPHICarbon, Lehigh, Monroe, Northampton64 min
Jul 6, 4:06 PM EDTSevere Thunderstorm WarningPHILehigh24 min
Jul 6, 4:07 PM EDTFlash Flood WarningPHIChester, Delaware, Montgomery4 hr
Jul 6, 4:31 PM EDTSevere Thunderstorm WarningPHIBerks, Lehigh, Monroe, Northampton44 min
Jul 6, 4:51 PM EDTAreal Flood AdvisoryPHICarbon, Monroe114 min
Jul 6, 5:00 PM EDTSevere Thunderstorm WarningPHIBerks, Carbon, Lehigh, Monroe, Northampton45 min
Jul 6, 5:01 PM EDTAreal Flood AdvisoryPHIBerks, Carbon, Lehigh, Monroe, Northampton119 min
Jul 6, 5:14 PM EDTSevere Thunderstorm WarningPHIChester61 min
Jul 6, 5:17 PM EDTSevere Thunderstorm WarningPHIBerks, Bucks, Lehigh, Montgomery, Northampton43 min
Jul 6, 5:20 PM EDTSevere Thunderstorm WarningPHIChester, Delaware42 min
Jul 6, 5:29 PM EDTSevere Thunderstorm WarningPHIChester46 min
Jul 6, 5:43 PM EDTAreal Flood AdvisoryPHIChester, Delaware3 hr
Jul 6, 5:53 PM EDTSevere Thunderstorm WarningPHIBerks, Bucks, Chester, Lehigh, Montgomery52 min
Jul 6, 6:13 PM EDTSevere Thunderstorm WarningPHIChester48 min
Jul 6, 6:14 PM EDTAreal Flood AdvisoryPHIBerks, Chester, Montgomery3 hr
Jul 6, 6:18 PM EDTSevere Thunderstorm WarningPHIBerks, Chester, Montgomery35 min
Jul 6, 6:54 PM EDTFlash Flood WarningPHIBerks, Chester, Montgomery109 min
Jul 6, 7:18 PM EDTSevere Thunderstorm WarningPHIMonroe36 min
Jul 6, 7:36 PM EDTSevere Thunderstorm WarningPHIChester69 min

Nearby

Severe Thunderstorm Warnings in Pennsylvania, 2020Every 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.