Alert archive / Pennsylvania / Severe Thunderstorm Warnings in 2011

Severe Thunderstorm Warning 249, NWS Philadelphia/Mount Holly

August 18, 2011Delaware County, Philadelphia County, Pennsylvania; Gloucester County, Salem County, New Jersey; New Castle County, Delaware

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Aug 18, 2011, 7:37 PM EDT for Delaware County, Philadelphia County, Pennsylvania; Gloucester County, Salem County, New Jersey; New Castle County, Delaware. It was in force for 53 min. 4 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: Aug 18, 2011, 7:37 PM EDT (23:37 UTC)
Expired: Aug 18, 2011, 8:30 PM EDT
In force: 53 min
Issued by: NWS Philadelphia/Mount Holly
Area: Storm-based polygon

Counties New Castle County, DE, Gloucester County, NJ, Salem County, NJ, Delaware County, PA, Philadelphia County, PA

The radar

The Philadelphia radar (KDIX), 72 km from the middle of the area, began a volume at 23:40 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

Time	Report	Where
Aug 18, 7:40 PM EDT	HAIL 1	Boothwyn, PA
Aug 18, 7:40 PM EDT	HAIL 1	Claymont, DE
Aug 18, 7:45 PM EDT	HAIL 1	Claymont, DE
Aug 18, 8:02 PM EDT	TSTM WND GST 62	Philadelphia Intl Airpo, PA

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

The nearest sounding before it

Phillips Aaf/Abe, MD (KAPG), launched 12:00Z, 11.6 hours before the alert went out and 83 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-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

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: 780 J/kg
Mixed-layer CIN: -64 J/kg
Mixed-layer LCL: 1022 m above ground
0-6 km bulk shear: 16 kt
0-1 km storm-relative helicity: 83 m²/s²
0-3 km storm-relative helicity: 143 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

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

762 
WUUS51 KPHI 182337
SVRPHI
DEC003-NJC015-033-PAC045-101-190030-
/O.NEW.KPHI.SV.W.0249.110818T2337Z-110819T0030Z/

BULLETIN - EAS ACTIVATION REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
737 PM EDT THU AUG 18 2011

THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  NORTHEASTERN NEW CASTLE COUNTY IN NORTHERN DELAWARE...
  THIS INCLUDES THE CITY OF WILMINGTON...
  SOUTHEASTERN DELAWARE COUNTY IN SOUTHEAST PENNSYLVANIA...
  SOUTHWESTERN PHILADELPHIA COUNTY IN SOUTHEAST PENNSYLVANIA...
  NORTHWESTERN GLOUCESTER COUNTY IN SOUTHERN NEW JERSEY...
  NORTH CENTRAL SALEM COUNTY IN SOUTHERN NEW JERSEY...

* UNTIL 830 PM EDT

* AT 736 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
  SEVERE THUNDERSTORM CAPABLE OF PRODUCING QUARTER SIZE HAIL...AND
  DAMAGING WINDS IN EXCESS OF 60 MPH.  THIS STORM WAS LOCATED NEAR
  TALLEYVILLE...OR NEAR WILMINGTON...AND MOVING NORTHEAST AT 20 MPH.

* THE SEVERE THUNDERSTORM WILL BE NEAR...
  ARDEN AROUND 745 PM EDT...
  CHESTER AROUND 810 PM EDT...
  GIBBSTOWN AROUND 820 PM EDT...
  FOLCROFT...PHILADELPHIA INTERNATIONAL AIRPORT AND 6 MILES NORTHWEST
  OF PAULSBORO AROUND 825 PM EDT...
  SOUTH PHILADELPHIA AND 6 MILES NORTHWEST OF NATIONAL PARK AROUND
  830 PM EDT...

PRECAUTIONARY/PREPAREDNESS ACTIONS...

THIS IS A DANGEROUS STORM. IF YOU ARE IN ITS PATH...PREPARE
IMMEDIATELY FOR DAMAGING WINDS...DESTRUCTIVE 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.

&&

LAT...LON 3967 7507 3971 7556 3980 7560 3993 7515
      3990 7513 3988 7514 3986 7512
TIME...MOT...LOC 2337Z 239DEG 17KT 3979 7555

$$

HEAVENER

1 follow-up statement

221 
WWUS51 KPHI 190013
SVSPHI

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
813 PM EDT THU AUG 18 2011

DEC003-NJC033-190023-
/O.CAN.KPHI.SV.W.0249.000000T0000Z-110819T0030Z/
SALEM NJ-NEW CASTLE DE-
813 PM EDT THU AUG 18 2011

...THE SEVERE THUNDERSTORM WARNING FOR NORTHEASTERN NEW CASTLE AND
NORTH CENTRAL SALEM COUNTIES IS CANCELLED...

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.

LAT...LON 3974 7531 3988 7532 3993 7515 3990 7513
      3988 7514 3986 7512 3975 7509
TIME...MOT...LOC 0013Z 239DEG 17KT 3988 7536

$$

NJC015-PAC045-101-190030-
/O.CON.KPHI.SV.W.0249.000000T0000Z-110819T0030Z/
GLOUCESTER NJ-DELAWARE PA-PHILADELPHIA PA-
813 PM EDT THU AUG 18 2011

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 830 PM EDT
FOR SOUTHWESTERN PHILADELPHIA...SOUTHEASTERN DELAWARE AND NORTH
CENTRAL GLOUCESTER COUNTIES...

AT 810 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR CONTINUED TO
INDICATE A SEVERE THUNDERSTORM CAPABLE OF PRODUCING QUARTER SIZE
HAIL...AND DAMAGING WINDS IN EXCESS OF 60 MPH.  THIS STORM WAS
LOCATED NEAR NORWOOD...OR 13 MILES NORTHEAST OF WILMINGTON...MOVING
NORTHEAST AT 20 MPH.

THE SEVERE THUNDERSTORM WILL BE NEAR...
  GIBBSTOWN BY 820 PM EDT...
  NORWOOD...FOLCROFT AND 6 MILES NORTHWEST OF PAULSBORO BY 825 PM
  EDT...
  PHILADELPHIA INTERNATIONAL AIRPORT...SOUTH PHILADELPHIA...6 MILES
  NORTHWEST OF NATIONAL PARK AND 7 MILES NORTHWEST OF WEST DEPTFORD
  BY 830 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.

&&

LAT...LON 3974 7531 3988 7532 3993 7515 3990 7513
      3988 7514 3986 7512 3975 7509
TIME...MOT...LOC 0013Z 239DEG 17KT 3988 7536

$$

HEAVENER

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 18, 2:57 AM EDT	Special Weather Statement	PHI	Berks	63 min
Aug 18, 3:53 AM EDT	Special Weather Statement	PHI	Berks	52 min
Aug 18, 4:48 AM EDT	Special Weather Statement	PHI	Chester, Montgomery	57 min
Aug 18, 5:45 AM EDT	Special Weather Statement	PHI	Delaware, Montgomery, Philadelphia	60 min
Aug 18, 6:04 AM EDT	Special Weather Statement	PHI	Berks, Chester	41 min
Aug 18, 6:35 AM EDT	Areal Flood Advisory	PHI	Berks, Bucks, Chester, Delaware, Lehigh, Montgomery and 2 more	3 hr
Aug 18, 7:29 AM EDT	Special Weather Statement	PHI	Bucks, Delaware, Montgomery, Philadelphia	61 min
Aug 18, 8:16 AM EDT	Special Weather Statement	PHI	Philadelphia	59 min
Aug 18, 9:29 AM EDT	Areal Flood Advisory	PHI	Delaware	2 hr
Aug 18, 3:12 PM EDT	Flash Flood Watch	PHI	Berks, Carbon, Delaware, Lehigh, Monroe, Northampton and 1 more	29 hr
Aug 18, 5:30 PM EDT	Special Weather Statement	PHI	Monroe	60 min
Aug 18, 5:48 PM EDT	Severe Thunderstorm Warning	PHI	Chester	57 min
Aug 18, 6:18 PM EDT	Special Weather Statement	PHI	Chester	57 min
Aug 18, 6:39 PM EDT	Severe Thunderstorm Warning	PHI	Chester	66 min
Aug 18, 6:59 PM EDT	Flash Flood Warning	PHI	Chester	2 hr
Aug 18, 7:14 PM EDT	Severe Thunderstorm Warning	PHI	Chester, Delaware	50 min
Aug 18, 7:28 PM EDT	Special Weather Statement	PHI	Chester	62 min
Aug 18, 7:31 PM EDT	Special Weather Statement	PHI	Monroe	59 min
Aug 18, 7:47 PM EDT	Areal Flood Advisory	PHI	Carbon, Monroe, Northampton	3 hr
Aug 18, 7:58 PM EDT	Severe Thunderstorm Warning	PHI	Bucks, Montgomery	31 min
Aug 18, 7:59 PM EDT	Severe Thunderstorm Warning	PHI	Bucks, Delaware, Montgomery, Philadelphia	61 min
Aug 18, 4:53 AM EDT	Special Weather Statement	PHI	Morris, Somerset, Sussex	52 min
Aug 18, 8:57 AM EDT	Areal Flood Advisory	PHI	Atlantic, Burlington, Camden, Cumberland, Gloucester, Monmouth and 1 more	3 hr
Aug 18, 3:32 PM EDT	Special Weather Statement	PHI	Burlington	58 min
Aug 18, 3:50 PM EDT	Areal Flood Advisory	PHI	Burlington, Camden	51 min
Aug 18, 4:17 PM EDT	Special Weather Statement	PHI	Monmouth	58 min
Aug 18, 4:55 PM EDT	Special Weather Statement	PHI	Burlington	65 min
Aug 18, 5:20 PM EDT	Severe Thunderstorm Warning	PHI	Burlington, Monmouth, Ocean	33 min
Aug 18, 6:12 PM EDT	Special Weather Statement	PHI	Middlesex	63 min
Aug 18, 6:33 PM EDT	Special Weather Statement	PHI	Mercer	57 min
Aug 18, 7:34 PM EDT	Special Weather Statement	PHI	Monmouth	56 min
Aug 18, 7:43 PM EDT	Severe Thunderstorm Warning	PHI	Morris, Sussex, Warren	62 min
Aug 18, 6:44 PM EDT	Special Weather Statement	PHI	New Castle	61 min

Nearby

Severe Thunderstorm Warnings in Pennsylvania, 2011 Severe Thunderstorm Warnings in New Jersey, 2011 Severe Thunderstorm Warnings in Delaware, 2011 Every severe thunderstorm warning in 2011

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.