Alert archive / Pennsylvania / Severe Thunderstorm Warnings in 2012

Severe Thunderstorm Warning 85, NWS Philadelphia/Mount Holly

July 7, 2012Chester County, Delaware County, Pennsylvania

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Jul 7, 2012, 9:05 PM EDT for Chester County, Delaware County, Pennsylvania. It was in force for 32 min. 2 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 7, 2012, 9:05 PM EDT (01:05 UTC)
Expired
Jul 7, 2012, 9:37 PM EDT
In force
32 min
Issued by
NWS Philadelphia/Mount Holly
Area
Storm-based polygon

Counties Chester County, PA, Delaware County, PA

The radar

The Philadelphia radar (KDIX), 114 km from the middle of the area, began a volume at 01:05 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 7, 9:18 PM EDTHAIL 0.88Coatesville, PA
Jul 7, 9:22 PM EDTHAIL 1Coatesville, PA

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 7, 6:14 PM EDTSevere Thunderstorm WatchSPC3 hr

The nearest sounding before it

Washington/Dulle, VA (KIAD), launched 00:00Z, 1.1 hours before the alert went out and 179 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 00:00Z on 2012-07-08Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 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 00:00Z on 2012-07-08The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 39 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
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
0 m above ground
0-6 km bulk shear
32 kt
0-1 km storm-relative helicity
39 m²/s²
0-3 km storm-relative helicity
75 m²/s²
Significant tornado parameter
0.0
Supercell composite
2.4

Open this sounding in Storm Lab

The text

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

873 
WUUS51 KPHI 080105
SVRPHI
PAC029-045-080200-
/O.NEW.KPHI.SV.W.0085.120708T0105Z-120708T0200Z/

BULLETIN - EAS ACTIVATION REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
905 PM EDT SAT JUL 7 2012

THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  CHESTER COUNTY IN SOUTHEAST PENNSYLVANIA...
  THIS INCLUDES THE CITY OF WEST CHESTER...
  DELAWARE COUNTY IN SOUTHEAST PENNSYLVANIA...

* UNTIL 1000 PM EDT

* AT 901 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
  LINE OF SEVERE THUNDERSTORMS CAPABLE OF PRODUCING DAMAGING WINDS IN
  EXCESS OF 60 MPH.  THESE STORMS WERE LOCATED ALONG A LINE EXTENDING
  FROM 7 MILES WEST OF HONEY BROOK TO 6 MILES WEST OF PARKESBURG TO
  11 MILES WEST OF MOUNT VERNON...OR ALONG A LINE EXTENDING FROM 14
  MILES EAST OF LANCASTER TO 15 MILES EAST OF LANCASTER TO 14 MILES
  SOUTH OF LANCASTER...AND MOVING EAST AT 45 MPH.

* SEVERE THUNDERSTORMS WILL BE NEAR...
  MOUNT VERNON...HOMEVILLE...COCHRANVILLE AND COATESVILLE AROUND 915
  PM EDT...
  GLENMOORE AND OXFORD AROUND 920 PM EDT...
  DOWNINGTOWN AROUND 925 PM EDT...
  CHESTER SPRINGS...WEST GROVE AND MARSHALLTON AROUND 930 PM EDT...

PRECAUTIONARY/PREPAREDNESS ACTIONS...

THIS IS A DANGEROUS STORM. IF YOU ARE IN ITS PATH...PREPARE
IMMEDIATELY FOR DAMAGING WINDS...LARGE HAIL...AND DEADLY CLOUD TO
GROUND LIGHTNING. PEOPLE OUTSIDE SHOULD MOVE TO A SHELTER...
PREFERABLY INSIDE A STRONG BUILDING BUT AWAY FROM WINDOWS.

PLEASE REPORT HAIL OR STRONG WINDS TO THE NATIONAL WEATHER SERVICE BY
CALLING TOLL FREE...1-877-633-6772...WHEN YOU CAN DO SO SAFELY.

A SEVERE THUNDERSTORM WATCH REMAINS IN EFFECT UNTIL MIDNIGHT EDT
SUNDAY MORNING FOR NORTHERN DELAWARE AND NORTHEAST MARYLAND AND
SOUTHERN NEW JERSEY AND SOUTHEAST PENNSYLVANIA.

&&

LAT...LON 3985 7603 3988 7600 3996 7600 4003 7594
      4011 7595 4012 7593 4008 7540 4001 7530
      4000 7530 3985 7540 3983 7552 3984 7560
      3979 7576 3978 7605
TIME...MOT...LOC 0106Z 267DEG 40KT 4008 7597 3996 7596
          3984 7615

$$

HAYES
2 follow-up statements
601 
WWUS51 KPHI 080123
SVSPHI

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
923 PM EDT SAT JUL 7 2012

PAC029-045-080200-
/O.CON.KPHI.SV.W.0085.000000T0000Z-120708T0200Z/
DELAWARE PA-CHESTER PA-
923 PM EDT SAT JUL 7 2012

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 1000 PM EDT
FOR CENTRAL CHESTER AND DELAWARE COUNTIES...

AT 922 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR CONTINUED TO
INDICATE A LINE OF SEVERE THUNDERSTORMS CAPABLE OF PRODUCING DAMAGING
WINDS IN EXCESS OF 60 MPH.  THESE STORMS WERE LOCATED ALONG A LINE
EXTENDING FROM GLENMOORE TO MODENA...OR ALONG A LINE EXTENDING FROM
11 MILES NORTHWEST OF WEST CHESTER TO 9 MILES WEST OF WEST CHESTER...
MOVING EAST AT 40 MPH.

SEVERE THUNDERSTORMS WILL BE NEAR...
  MARSHALLTON AND LIONVILLE BY 930 PM EDT...
  WEST CHESTER AND EXTON BY 935 PM EDT...
  ELAM...WESTTOWN...CONCORDVILLE AND CHEYNEY BY 940 PM EDT...
  CHESTERBROOK AND CHELSEA BY 945 PM EDT...

PRECAUTIONARY/PREPAREDNESS ACTIONS...

PLEASE REPORT HAIL OR STRONG WINDS TO THE NATIONAL WEATHER SERVICE BY
CALLING TOLL FREE...1-877-633-6772...WHEN YOU CAN DO SO SAFELY.

A SEVERE THUNDERSTORM WATCH REMAINS IN EFFECT UNTIL MIDNIGHT EDT
SUNDAY MORNING FOR NORTHERN DELAWARE AND NORTHEAST MARYLAND AND
SOUTHERN NEW JERSEY AND SOUTHEAST PENNSYLVANIA.

&&

LAT...LON 3996 7595 4009 7589 4008 7541 4001 7530
      3985 7540 3983 7552 3984 7561 3982 7567
      3981 7593 3988 7597
TIME...MOT...LOC 0123Z 269DEG 36KT 4007 7575 3996 7577

$$

HAYES
307 
WWUS51 KPHI 080137
SVSPHI

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
937 PM EDT SAT JUL 7 2012

PAC029-045-080147-
/O.CAN.KPHI.SV.W.0085.000000T0000Z-120708T0200Z/
DELAWARE PA-CHESTER PA-
937 PM EDT SAT JUL 7 2012

...THE SEVERE THUNDERSTORM WARNING FOR CENTRAL CHESTER AND DELAWARE
COUNTIES IS CANCELLED...

THE STORM THAT PROMPTED THE WARNING HAS WEAKENED AND IS NO LONGER 
EXPECTED TO PRODUCE SEVERE WEATHER.

PLEASE REPORT HAIL OR STRONG WINDS TO THE NATIONAL WEATHER SERVICE BY
CALLING TOLL FREE...1-877-633-6772...WHEN YOU CAN DO SO SAFELY.

A SEVERE THUNDERSTORM WATCH REMAINS IN EFFECT UNTIL MIDNIGHT EDT
SUNDAY MORNING FOR NORTHERN DELAWARE AND NORTHEAST MARYLAND AND
SOUTHERN NEW JERSEY AND SOUTHEAST PENNSYLVANIA.

LAT...LON 3996 7595 4009 7589 4008 7541 4001 7530
      3985 7540 3983 7552 3984 7561 3982 7567
      3981 7593 3988 7597
TIME...MOT...LOC 0137Z 267DEG 40KT 4009 7552 3997 7551
          3985 7570

$$

HAYES

The office that day

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

IssuedProductOfficeCountiesLasted
Jul 7, 8:45 PM EDTSpecial Weather StatementPHIChester60 min
Jul 7, 10:50 PM EDTSpecial Weather StatementPHIMonroe, Northampton55 min
Jul 7, 11:36 PM EDTSpecial Weather StatementPHICarbon, Monroe, Northampton54 min
Jul 8, 1:06 AM EDTSpecial Weather StatementPHINorthampton54 min

Nearby

Severe Thunderstorm Warnings in Pennsylvania, 2012Every severe thunderstorm warning in 2012

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.