Alert archive / Pennsylvania / Severe Thunderstorm Warnings in 2013

Severe Thunderstorm Warning 77, NWS Philadelphia/Mount Holly

July 20, 2013Montgomery County, Philadelphia County, Pennsylvania; Burlington County, Camden County, New Jersey

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Jul 20, 2013, 9:59 PM EDT for Montgomery County, Philadelphia County, Pennsylvania; Burlington County, Camden County, New Jersey. It was in force for 61 min. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued
Jul 20, 2013, 9:59 PM EDT (01:59 UTC)
Expired
Jul 20, 2013, 11:00 PM EDT
In force
61 min
Issued by
NWS Philadelphia/Mount Holly
Area
Storm-based polygon

Counties Burlington County, NJ, Camden County, NJ, Montgomery County, PA, Philadelphia County, PA

The radar

The Philadelphia radar (KDIX), 56 km from the middle of the area, began a volume at 01:59 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.

The nearest sounding before it

Brookhaven, NY (KOKX), launched 00:00Z, 2.0 hours before the alert went out and 208 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, Brookhaven, NY at 00:00Z on 2013-07-21Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1732 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, Brookhaven, NY at 00:00Z on 2013-07-21The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 21 square meters per square second.193958Sfc1 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
1732 J/kg
Mixed-layer CIN
-38 J/kg
Mixed-layer LCL
1353 m above ground
0-6 km bulk shear
35 kt
0-1 km storm-relative helicity
21 m²/s²
0-3 km storm-relative helicity
34 m²/s²
Significant tornado parameter
0.1
Supercell composite
0.9

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

513 
WUUS51 KPHI 210159
SVRPHI
NJC005-007-PAC091-101-210300-
/O.NEW.KPHI.SV.W.0077.130721T0159Z-130721T0300Z/

BULLETIN - EAS ACTIVATION REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
959 PM EDT SAT JUL 20 2013

THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  NORTHWESTERN CAMDEN COUNTY IN SOUTHERN NEW JERSEY...
  SOUTHEASTERN MONTGOMERY COUNTY IN SOUTHEAST PENNSYLVANIA...
  PHILADELPHIA COUNTY IN SOUTHEAST PENNSYLVANIA...
  NORTHWESTERN BURLINGTON COUNTY IN SOUTHERN NEW JERSEY...

* UNTIL 1100 PM EDT

* AT 955 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
  SEVERE THUNDERSTORM. THE STORM WAS NEAR BRYN MAWR...MOVING EAST AT
  15 MPH. THIS STORM IS CAPABLE OF PRODUCING DAMAGING WINDS IN EXCESS
  OF 60 MPH. 

* THE SEVERE THUNDERSTORM WILL BE NEAR...
  CHESTNUT HILL AROUND 1005 PM EDT...
  GERMANTOWN AND ROXBOROUGH AROUND 1010 PM EDT...
  JENKINTOWN AROUND 1020 PM EDT...
  PHILADELPHIA AND KENSINGTON AROUND 1025 PM EDT...
  CAMDEN AROUND 1030 PM EDT...
  WISSINOMING AND TACONY AROUND 1035 PM EDT...

PRECAUTIONARY/PREPAREDNESS ACTIONS...

SEVERE THUNDERSTORMS PRODUCE WINDS OF MORE THAN 57 MPH...OR HAIL ONE
INCH OR LARGER.

FREQUENT CLOUD TO GROUND LIGHTNING IS OCCURRING WITH THIS SEVERE
THUNDERSTORM. WHEN THUNDER ROARS...MOVE INDOORS! REMEMBER...IF YOU
CAN HEAR THUNDER...YOU ARE CLOSE ENOUGH TO BE STRUCK BY LIGHTNING.

&&

LAT...LON 3989 7499 3999 7529 4002 7532 4014 7524
      4008 7496 4007 7498 4005 7497 4007 7494
      4006 7487
TIME...MOT...LOC 0158Z 283DEG 15KT 4004 7526

$$

FORECASTER: HEAVENER
2 follow-up statements
832 
WWUS51 KPHI 210220
SVSPHI

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
1020 PM EDT SAT JUL 20 2013

PAC091-210230-
/O.CAN.KPHI.SV.W.0077.000000T0000Z-130721T0300Z/
MONTGOMERY PA-
1020 PM EDT SAT JUL 20 2013

...THE SEVERE THUNDERSTORM WARNING FOR SOUTHEASTERN MONTGOMERY COUNTY
IS CANCELLED...

THE STORM THAT PROMPTED THE SEVERE THUNDERSTORM WARNING HAS MOVED OUT
OF THE AREA...THEREFORE THE SEVERE THUNDERSTORM WARNING HAS BEEN
CANCELLED.

LAT...LON 4003 7489 3989 7499 3992 7509 3997 7517
      4005 7511 4006 7509 4007 7510 4008 7509
      4008 7508
TIME...MOT...LOC 0220Z 283DEG 15KT 4002 7514

$$

NJC005-007-PAC101-210300-
/O.CON.KPHI.SV.W.0077.000000T0000Z-130721T0300Z/
CAMDEN NJ-PHILADELPHIA PA-BURLINGTON NJ-
1020 PM EDT SAT JUL 20 2013

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 1100 PM EDT
FOR WEST CENTRAL BURLINGTON...CENTRAL PHILADELPHIA AND NORTHWESTERN
CAMDEN COUNTIES...

AT 1016 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR CONTINUED TO
INDICATE A SEVERE THUNDERSTORM CAPABLE OF PRODUCING DAMAGING WINDS IN
EXCESS OF 60 MPH. THIS STORM WAS LOCATED NEAR PHILADELPHIA...MOVING
EAST AT 15 MPH.

THE SEVERE THUNDERSTORM WILL BE NEAR...
PHILADELPHIA AND KENSINGTON AROUND 1025 PM EDT...
CAMDEN AROUND 1030 PM EDT...
WISSINOMING AND TACONY AROUND 1035 PM EDT...
PALMYRA AND PENNSAUKEN AROUND 1040 PM EDT...
RIVERTON AROUND 1045 PM EDT...
CINNAMINSON AND MAPLE SHADE AROUND 1050 PM EDT...

LAT...LON 4003 7489 3989 7499 3992 7509 3997 7517
      4005 7511 4006 7509 4007 7510 4008 7509
      4008 7508
TIME...MOT...LOC 0220Z 283DEG 15KT 4002 7514

$$

FORECASTER: HEAVENER
624 
WWUS51 KPHI 210236
SVSPHI

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
1036 PM EDT SAT JUL 20 2013

NJC005-007-PAC101-210246-
/O.CAN.KPHI.SV.W.0077.000000T0000Z-130721T0300Z/
CAMDEN NJ-PHILADELPHIA PA-BURLINGTON NJ-
1036 PM EDT SAT JUL 20 2013

...THE SEVERE THUNDERSTORM WARNING FOR WEST CENTRAL BURLINGTON...
CENTRAL PHILADELPHIA AND NORTHWESTERN CAMDEN COUNTIES IS CANCELLED...

THE STORM HAS WEAKENED TO BELOW SEVERE LIMITS...THEREFORE THE SEVERE
THUNDERSTORM WARNING HAS BEEN CANCELLED.

LAT...LON 4003 7489 3989 7499 3992 7509 3997 7517
      4005 7511 4006 7509 4007 7510 4008 7509
      4008 7508
TIME...MOT...LOC 0236Z 283DEG 15KT 4000 7506

$$

FORECASTER: HEAVENER

The office that day

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

IssuedProductOfficeCountiesLasted
Jul 20, 8:39 PM EDTSpecial Weather StatementPHIDelaware66 min
Jul 20, 8:49 PM EDTSevere Thunderstorm WarningPHIDelaware, Philadelphia56 min
Jul 21, 3:44 PM EDTSpecial Weather StatementPHIDelaware, Philadelphia2 hr
Jul 21, 5:03 PM EDTAreal Flood AdvisoryPHIBucks3 hr
Jul 20, 8:33 PM EDTSpecial Weather StatementPHICamden57 min
Jul 20, 9:13 PM EDTSpecial Weather StatementPHIOcean32 min
Jul 20, 9:38 PM EDTSevere Thunderstorm WarningPHIBurlington67 min
Jul 20, 9:51 PM EDTSevere Thunderstorm WarningPHIAtlantic, Burlington, Ocean54 min
Jul 20, 10:07 PM EDTSpecial Marine WarningPHI83 min
Jul 20, 10:46 PM EDTSpecial Weather StatementPHIBurlington59 min
Jul 20, 10:52 PM EDTSpecial Weather StatementPHIAtlantic53 min
Jul 20, 11:10 PM EDTSpecial Marine WarningPHI95 min
Jul 21, 3:10 PM EDTSpecial Weather StatementPHIOcean65 min
Jul 21, 3:17 PM EDTCoastal Flood AdvisoryPHIMiddlesex, Monmouth, Ocean6 hr
Jul 21, 4:16 PM EDTSpecial Weather StatementPHIBurlington89 min
Jul 21, 4:20 PM EDTAreal Flood AdvisoryPHIBurlington3 hr
Jul 21, 4:44 PM EDTSpecial Weather StatementPHIBurlington61 min
Jul 21, 5:18 PM EDTSevere Thunderstorm WarningPHIBurlington57 min
Jul 21, 5:28 PM EDTAreal Flood AdvisoryPHIBurlington3 hr
Jul 21, 5:52 PM EDTSpecial Weather StatementPHIOcean53 min
Jul 21, 6:20 PM EDTSpecial Weather StatementPHIAtlantic55 min
Jul 21, 6:33 PM EDTAreal Flood AdvisoryPHIBurlington, Ocean3 hr
Jul 21, 7:02 PM EDTSpecial Weather StatementPHIAtlantic88 min
Jul 21, 7:04 PM EDTSpecial Marine WarningPHI56 min
Jul 21, 7:25 PM EDTAreal Flood AdvisoryPHIAtlantic, Burlington3 hr

Nearby

Severe Thunderstorm Warnings in Pennsylvania, 2013Severe Thunderstorm Warnings in New Jersey, 2013Every severe thunderstorm warning in 2013

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.