Alert archive / Pennsylvania / Severe Thunderstorm Warnings in 2020

Severe Thunderstorm Warning 125, NWS Philadelphia/Mount Holly

July 6, 20204 counties in Pennsylvania

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Jul 6, 2020, 3:52 PM EDT for 4 counties in Pennsylvania. It was in force for 38 min. 5 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, 3:52 PM EDT (19:52 UTC)
Expired
Jul 6, 2020, 4:30 PM EDT
In force
38 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), 95 km from the middle of the area, began a volume at 19:54 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, 3:58 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.
Jul 6, 4:17 PM EDTHAIL 0.75Berwyn, PAMPING REPORT.
Jul 6, 4:24 PM EDTTSTM WND DMG1 S East Whiteland Twp, PADOWNED TREE NEAR THE INTERSECTION OF SPROUL ROAD AND THREE TUN ROAD IN EAST WHITELAND TWP. TIME ESTIMATED FROM RADAR.
Jul 6, 4:29 PM EDTTSTM WND DMG1 S Spring City, PATREE DOWN IN WIRES ON VALLEY PARK RD AT POTHOUSE RD. 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, 7.9 hours before the alert went out and 211 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.

087 
WUUS51 KPHI 061952
SVRPHI
PAC029-045-091-101-062030-
/O.NEW.KPHI.SV.W.0125.200706T1952Z-200706T2030Z/

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

The National Weather Service in Mount Holly NJ has issued a

* Severe Thunderstorm Warning for...
  Southern Montgomery County in southeastern Pennsylvania...
  Northeastern Chester County in southeastern Pennsylvania...
  Northwestern Philadelphia County in southeastern Pennsylvania...
  Northeastern Delaware County in southeastern Pennsylvania...

* Until 430 PM EDT.

* At 352 PM EDT, severe thunderstorms were located along a line
  extending from near Royersford to Valley Forge to Conshohocken,
  moving southeast 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, Pottstown, Phoenixville, West Norriton,
  East Norriton, Conshohocken, Ambler, Collegeville, Royersford,
  Jenkintown, Narberth, Trappe, East Lansdowne, Rockledge, Morris
  Park, Pughtown, Bryn Mawr, Trout Lake and Radnor Township.

This includes the following highways...
 Pennsylvania Turnpike between mile markers 313 and 339.
 Northeast Extension between mile markers 21 and 26.
 Interstate 76 in Pennsylvania between mile markers 327 and 341.
 Interstate 476 in Pennsylvania between mile markers 6 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 4024 7570 4025 7550 4020 7531 4009 7505
      3993 7529 4001 7562 4021 7575
TIME...MOT...LOC 1952Z 306DEG 5KT 4020 7560 4010 7543 4006 7529 

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, 3:11 PM EDTSevere Thunderstorm WarningPHIChester, Delaware, Montgomery, Philadelphia49 min
Jul 6, 3:38 PM EDTSevere Thunderstorm WarningPHIBucks, Lehigh, Northampton52 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.