Alert archive / Pennsylvania / Severe Thunderstorm Warnings in 2020

Severe Thunderstorm Warning 111, NWS Philadelphia/Mount Holly

July 6, 2020Montgomery County, Pennsylvania

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Jul 6, 2020, 2:27 PM EDT for Montgomery County, Pennsylvania. It was in force for 48 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, 2:27 PM EDT (18:27 UTC)
Expired
Jul 6, 2020, 3:15 PM EDT
In force
48 min
Issued by
NWS Philadelphia/Mount Holly
Area
Storm-based polygon
Hail
1.0 in
Wind
60.0 mph

County Montgomery County, PA

The radar

The Philadelphia radar (KDIX), 97 km from the middle of the area, began a volume at 18:27 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, 2:28 PM EDTTSTM WND DMG2 Sse Collegeville, PADOWNED POWER LINES ON LANDIS MILL ROAD NEAR LEVEL ROAD IN COLLEGEVILLE. TIME ESTIMATED FROM RADAR.
Jul 6, 2:30 PM EDTHAIL 0.5East Norriton, PAREPORT VIA SOCIAL MEDIA WITH PHOTO.
Jul 6, 2:43 PM EDTTSTM WND DMG1 Ene Oaks, PACORRECTS PREVIOUS TSTM WND DMG REPORT FROM 1 ENE OAKS. DOWNED TREE ON EAGLEVILLE ROAD NEAR PINETOWN ROAD IN OAKS. TIME ESTIMATED FROM RADAR.
Jul 6, 2:43 PM EDTHAIL 1Plymouth Twp, PAMPING REPORT.
Jul 6, 2:45 PM EDTTSTM WND DMG1 Ese Norristown, PADOWNED TREE ON HILLSIDE AVENUE NEAR COLEMAN STREET IN NORRISTOWN. TIME ESTIMATED FROM RADAR.
Jul 6, 2:55 PM EDTHAIL 1Eagleville, PAMAINLY HALF INCH TO PENNY SIZE BUT A FEW QUARTER SIZE.
Jul 6, 3:00 PM EDTHAIL 1Upper Providence Twp, PAHAIL OF AROUND ONE INCH IN DIAMETER.
Jul 6, 3:00 PM EDTHAIL 1West Norriton, PAREPORT VIA SOCIAL MEDIA WITH A PHOTO OF HAIL TO ABOUT QUARTER SIZE. TIME ESTIMATED FROM RADAR.
Jul 6, 3:15 PM EDTHAIL 11 N Oaks, PAMULTIPLE REPORTS OF HAIL NEAR COLLEGEVILLE, WITH A PHOTO OF HAIL UP TO QUARTER SIZE.

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, 6.5 hours before the alert went out and 215 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.

094 
WUUS51 KPHI 061827
SVRPHI
PAC091-061915-
/O.NEW.KPHI.SV.W.0111.200706T1827Z-200706T1915Z/

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

The National Weather Service in Mount Holly NJ has issued a

* Severe Thunderstorm Warning for...
  Central Montgomery County in southeastern Pennsylvania...

* Until 315 PM EDT.

* At 227 PM EDT, a severe thunderstorm was located over Collegeville,
  or 18 miles northeast of West Chester, moving southeast 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...
  Norristown, West Norriton, East Norriton, Conshohocken,
  Collegeville, Royersford, Trappe, Schwenksville, King Of Prussia,
  Spring Mount, Plymouth Meeting, Skippack, Bridgeport, West
  Conshohocken, Evansburg, Audubon, Eagleville, Trooper, Kulpsville
  and Sanatoga.

This includes the following highways...
 Pennsylvania Turnpike between mile markers 328 and 333.
 Northeast Extension between mile markers 22 and 29.
 Interstate 76 in Pennsylvania between mile markers 330 and 333.
 Interstate 476 in Pennsylvania between mile markers 16 and 19.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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 4032 7558 4023 7529 4003 7528 4019 7555
      4021 7556 4020 7557 4021 7559
TIME...MOT...LOC 1827Z 293DEG 19KT 4018 7541 

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

Gorse
1 follow-up statement
274 
WWUS51 KPHI 061843
SVSPHI

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

PAC091-061915-
/O.CON.KPHI.SV.W.0111.000000T0000Z-200706T1915Z/
Montgomery PA-
243 PM EDT Mon Jul 6 2020

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 315 PM EDT
FOR CENTRAL MONTGOMERY COUNTY...

At 242 PM EDT, a severe thunderstorm was located over East Norriton,
or 13 miles northwest of Philadelphia, moving southeast 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...
Norristown, West Norriton, East Norriton, Conshohocken, Collegeville,
Royersford, Trappe, Schwenksville, King Of Prussia, Spring Mount,
Plymouth Meeting, Skippack, Bridgeport, West Conshohocken, Evansburg,
Audubon, Eagleville, Trooper, Kulpsville and Sanatoga.

This includes the following highways...
 Pennsylvania Turnpike between mile markers 328 and 333.
 Northeast Extension between mile markers 22 and 29.
 Interstate 76 in Pennsylvania between mile markers 330 and 333.
 Interstate 476 in Pennsylvania between mile markers 16 and 19.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Frequent cloud to ground lightning is occurring with this storm. 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 4032 7558 4023 7529 4003 7528 4019 7555
      4021 7556 4020 7557 4021 7559
TIME...MOT...LOC 1842Z 293DEG 19KT 4015 7531 

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

Gorse

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, 2:28 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, 3:52 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.