Alert archive / Pennsylvania / Severe Thunderstorm Warnings in 2011

Severe Thunderstorm Warning 27, NWS Philadelphia/Mount Holly

April 28, 20118 counties in Pennsylvania; Hunterdon County, Warren County, New Jersey; New Castle County, Delaware

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Apr 28, 2011, 6:56 AM EDT for 8 counties in Pennsylvania; Hunterdon County, Warren County, New Jersey; New Castle County, Delaware. It was in force for 34 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: Apr 28, 2011, 6:56 AM EDT (10:56 UTC)
Expired: Apr 28, 2011, 7:30 AM EDT
In force: 34 min
Issued by: NWS Philadelphia/Mount Holly
Area: Storm-based polygon

Counties New Castle County, DE, Hunterdon County, NJ, Warren County, NJ, Berks County, PA, Bucks County, PA, Chester County, PA, Delaware County, PA, Lehigh County, PA, Montgomery County, PA, Northampton County, PA, Philadelphia County, PA

The radar

The Philadelphia radar (KDIX), 94 km from the middle of the area, began a volume at 10:56 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 watch it was issued in

The SPC watch in force over the same counties when this warning went out.

Issued	Product	Office	Lasted
Apr 28, 4:05 AM EDT	Severe Thunderstorm Watch	SPC	6 hr

The nearest sounding before it

Brookhaven, NY (KOKX), launched 00:00Z, 10.9 hours before the alert went out and 217 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: 172 J/kg
Mixed-layer CIN: -34 J/kg
Mixed-layer LCL: 447 m above ground
0-6 km bulk shear: 32 kt
0-1 km storm-relative helicity: 207 m²/s²
0-3 km storm-relative helicity: 246 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.

900 
WUUS51 KPHI 281056
SVRPHI
DEC003-NJC019-041-PAC011-017-029-045-077-091-095-101-281200-
/O.NEW.KPHI.SV.W.0027.110428T1056Z-110428T1200Z/

BULLETIN - EAS ACTIVATION REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
656 AM EDT THU APR 28 2011

THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  SOUTHEASTERN BERKS COUNTY IN EASTERN PENNSYLVANIA...
  SOUTHEASTERN LEHIGH COUNTY IN EASTERN PENNSYLVANIA...
  THIS INCLUDES THE CITY OF ALLENTOWN...
  NORTHAMPTON COUNTY IN EASTERN PENNSYLVANIA...
  THIS INCLUDES THE CITY OF EASTON...
  NORTHERN NEW CASTLE COUNTY IN NORTHERN DELAWARE...
  THIS INCLUDES THE CITIES OF...WILMINGTON...NEWARK...
  WESTERN HUNTERDON COUNTY IN NORTHWEST NEW JERSEY...
  WARREN COUNTY IN NORTHWEST NEW JERSEY...
  WESTERN BUCKS COUNTY IN SOUTHEAST PENNSYLVANIA...
  EASTERN CHESTER COUNTY IN SOUTHEAST PENNSYLVANIA...
  THIS INCLUDES THE CITY OF WEST CHESTER...
  DELAWARE COUNTY IN SOUTHEAST PENNSYLVANIA...
  MONTGOMERY COUNTY IN SOUTHEAST PENNSYLVANIA...
  NORTHWESTERN PHILADELPHIA COUNTY IN SOUTHEAST PENNSYLVANIA...

* UNTIL 800 AM EDT

* AT 652 AM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
  LINE OF SEVERE THUNDERSTORMS CAPABLE OF PRODUCING DAMAGING WINDS UP TO
  60 MPH. THESE STORMS WERE LOCATED ALONG A LINE EXTENDING
  FROM GILBERTSVILLE TO PUGHTOWN TO GLENMOORE TO LADENBERG...OR ALONG
  A LINE EXTENDING FROM 14 MILES EAST OF READING TO 16 MILES NORTH OF
  WEST CHESTER TO 11 MILES NORTHWEST OF WEST CHESTER TO NEWARK...AND
  MOVING NORTHEAST AT 70 MPH.

* SEVERE THUNDERSTORMS WILL BE NEAR...
  BALLY...ASHLAND...MARSHALLTON AND LIONVILLE AROUND 700 AM EDT...
  ZIONSVILLE...EMMAUS...ELAM AND CHELSEA AROUND 705 AM EDT...
  ALLENTOWN AND ROYERSFORD AROUND 710 AM 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.

A SEVERE THUNDERSTORM WATCH REMAINS IN EFFECT UNTIL 1000 AM EDT
THURSDAY MORNING FOR DELAWARE AND NORTHEASTERN MARYLAND AND WESTERN
NEW JERSEY AND EASTERN PENNSYLVANIA.

&&

LAT...LON 4090 7495 4074 7488 4032 7501 3969 7556
      3960 7578 4003 7583 4025 7583 4045 7568
      4102 7506
TIME...MOT...LOC 1055Z 220DEG 63KT 4036 7561 4023 7565
          4012 7571 3979 7575

$$

HEAVENER

2 follow-up statements

697 
WWUS51 KPHI 281114
SVSPHI

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
714 AM EDT THU APR 28 2011

PAC011-281124-
/O.CAN.KPHI.SV.W.0027.000000T0000Z-110428T1200Z/
BERKS PA-
714 AM EDT THU APR 28 2011

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

A SEVERE THUNDERSTORM WATCH REMAINS IN EFFECT UNTIL 1000 AM EDT
THURSDAY MORNING FOR DELAWARE AND NORTHEASTERN MARYLAND AND WESTERN
NEW JERSEY AND EASTERN PENNSYLVANIA.

LAT...LON 3967 7561 4011 7556 4032 7554 4049 7549
      4102 7506 4090 7495 4074 7488 4032 7501
      3971 7554
TIME...MOT...LOC 1114Z 220DEG 63KT 4061 7532 4048 7536
          4037 7543 4004 7547

$$

DEC003-NJC019-041-PAC017-029-045-077-091-095-101-281200-
/O.CON.KPHI.SV.W.0027.000000T0000Z-110428T1200Z/
WARREN NJ-HUNTERDON NJ-DELAWARE PA-PHILADELPHIA PA-CHESTER PA-
MONTGOMERY PA-LEHIGH PA-NORTHAMPTON PA-BUCKS PA-NEW CASTLE DE-
714 AM EDT THU APR 28 2011

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 800 AM EDT
FOR NORTHEASTERN NEW CASTLE...WESTERN BUCKS...EASTERN NORTHAMPTON...
SOUTHEASTERN LEHIGH...MONTGOMERY...EAST CENTRAL CHESTER...
NORTHWESTERN PHILADELPHIA...DELAWARE...WESTERN HUNTERDON AND WARREN
COUNTIES...

AT 710 AM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR CONTINUED TO
INDICATE A LINE OF SEVERE THUNDERSTORMS CAPABLE OF PRODUCING DAMAGING
WINDS UP TO 60 MPH.  THESE STORMS WERE LOCATED ALONG A LINE
EXTENDING FROM HELLERTOWN TO TRUMBAUERSVILLE TO GREEN LANE TO WEST
GOSHEN...OR ALONG A LINE EXTENDING FROM 6 MILES SOUTHEAST OF
ALLENTOWN TO 12 MILES SOUTH OF ALLENTOWN TO 19 MILES SOUTH OF
ALLENTOWN TO WEST CHESTER...MOVING NORTHEAST AT 70 MPH.

SEVERE THUNDERSTORMS WILL BE NEAR...
  FORKS...PALMER HEIGHTS...TATAMY AND STOCKERTOWN BY 720 AM EDT...
  FORT WASHINGTON...FLOURTOWN...HARMONY AND SPRING HOUSE BY 725 AM
  EDT...
  MAPLE GLEN AND HORSHAM BY 730 AM EDT...

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A SEVERE THUNDERSTORM WATCH REMAINS IN EFFECT UNTIL 1000 AM EDT
THURSDAY MORNING FOR DELAWARE AND NORTHEASTERN MARYLAND AND WESTERN
NEW JERSEY AND EASTERN PENNSYLVANIA.

&&

LAT...LON 3967 7561 4011 7556 4032 7554 4049 7549
      4102 7506 4090 7495 4074 7488 4032 7501
      3971 7554
TIME...MOT...LOC 1114Z 220DEG 63KT 4061 7532 4048 7536
          4037 7543 4004 7547

$$

HEAVENER

762 
WWUS51 KPHI 281130
SVSPHI

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
730 AM EDT THU APR 28 2011

DEC003-NJC019-041-PAC017-029-045-077-091-095-101-281140-
/O.CAN.KPHI.SV.W.0027.000000T0000Z-110428T1200Z/
WARREN NJ-HUNTERDON NJ-DELAWARE PA-PHILADELPHIA PA-CHESTER PA-
MONTGOMERY PA-LEHIGH PA-NORTHAMPTON PA-BUCKS PA-NEW CASTLE DE-
730 AM EDT THU APR 28 2011

...THE SEVERE THUNDERSTORM WARNING FOR NORTHEASTERN NEW CASTLE...
WESTERN BUCKS...EASTERN NORTHAMPTON...SOUTHEASTERN LEHIGH...
MONTGOMERY...EAST CENTRAL CHESTER...NORTHWESTERN PHILADELPHIA...
DELAWARE...WESTERN HUNTERDON AND WARREN COUNTIES IS CANCELLED...

A SEVERE THUNDERSTORM WATCH REMAINS IN EFFECT UNTIL 1000 AM EDT
THURSDAY MORNING FOR DELAWARE AND NORTHEASTERN MARYLAND AND WESTERN
NEW JERSEY AND EASTERN PENNSYLVANIA.

LAT...LON 3967 7561 4011 7556 4032 7554 4049 7549
      4102 7506 4090 7495 4074 7488 4032 7501
      3971 7554
TIME...MOT...LOC 1130Z 220DEG 63KT 4083 7509 4070 7513
          4059 7519 4026 7523

$$

HEAVENER

The office that day

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

Issued	Product	Office	Counties	Lasted
Apr 28, 4:24 AM EDT	Special Weather Statement	PHI	Berks, Carbon, Lehigh, Northampton	66 min
Apr 28, 4:36 AM EDT	Severe Thunderstorm Warning	PHI	Berks, Carbon, Lehigh, Monroe, Northampton	54 min
Apr 28, 5:31 AM EDT	Special Weather Statement	PHI	Carbon, Monroe	59 min
Apr 28, 5:49 AM EDT	Special Weather Statement	PHI	Carbon	56 min
Apr 28, 5:58 AM EDT	Areal Flood Advisory	PHI	Berks, Carbon, Lehigh, Monroe, Northampton	3 hr
Apr 28, 6:12 AM EDT	Special Weather Statement	PHI	Chester, Delaware, Philadelphia	63 min
Apr 28, 6:18 AM EDT	Severe Thunderstorm Warning	PHI	Carbon, Monroe	57 min
Apr 28, 6:23 AM EDT	Special Weather Statement	PHI	Berks, Chester, Lehigh, Montgomery	52 min
Apr 28, 7:06 AM EDT	Flash Flood Warning	PHI	Carbon, Monroe	6 hr
Apr 28, 7:35 AM EDT	Special Weather Statement	PHI	Bucks	55 min
Apr 28, 8:17 AM EDT	Special Weather Statement	PHI	Berks	58 min
Apr 28, 8:55 AM EDT	Severe Thunderstorm Warning	PHI	Berks, Lehigh	65 min
Apr 28, 8:59 AM EDT	Areal Flood Advisory	PHI	Berks, Lehigh	4 hr
Apr 28, 9:11 AM EDT	Special Weather Statement	PHI	Carbon, Monroe	49 min
Apr 28, 9:33 AM EDT	Severe Thunderstorm Warning	PHI	Carbon, Lehigh, Monroe, Northampton	57 min
Apr 28, 10:00 AM EDT	Severe Thunderstorm Warning	PHI	Berks, Bucks, Chester, Lehigh, Montgomery	60 min
Apr 28, 10:25 AM EDT	Severe Thunderstorm Warning	PHI	Bucks, Carbon, Lehigh, Monroe, Northampton	50 min
Apr 28, 10:48 AM EDT	Areal Flood Advisory	PHI	Bucks, Chester, Montgomery, Northampton	3 hr
Apr 28, 10:57 AM EDT	Severe Thunderstorm Warning	PHI	Berks, Bucks, Chester, Lehigh, Montgomery, Northampton	63 min
Apr 28, 10:58 AM EDT	Tornado Warning	PHI	Bucks, Northampton	32 min
Apr 28, 11:11 AM EDT	Severe Thunderstorm Warning	PHI	Northampton	64 min
Apr 28, 12:03 PM EDT	Special Weather Statement	PHI	Montgomery, Philadelphia	57 min
Apr 28, 12:11 PM EDT	Severe Thunderstorm Warning	PHI	Bucks, Chester, Delaware, Montgomery	31 min
Apr 28, 12:42 PM EDT	Special Weather Statement	PHI	Delaware	63 min
Apr 28, 12:45 PM EDT	Special Weather Statement	PHI	Bucks, Delaware, Montgomery, Philadelphia	60 min
Apr 28, 1:23 PM EDT	Areal Flood Advisory	PHI	Philadelphia	103 min
Apr 28, 9:00 AM EDT	Special Weather Statement	PHI	Monmouth	60 min
Apr 28, 9:02 AM EDT	Special Marine Warning	PHI		26 min
Apr 28, 10:10 AM EDT	Gale Warning	PHI		5 hr
Apr 28, 11:15 AM EDT	Areal Flood Advisory	PHI	Mercer, Middlesex, Morris, Somerset	4 hr
Apr 28, 11:22 AM EDT	Tornado Warning	PHI	Hunterdon, Morris, Sussex, Warren	23 min
Apr 28, 11:45 AM EDT	Tornado Warning	PHI	Morris	30 min
Apr 28, 12:06 PM EDT	Special Marine Warning	PHI		43 min
Apr 28, 12:29 PM EDT	Special Weather Statement	PHI	Camden, Gloucester, Salem	61 min
Apr 28, 12:34 PM EDT	Special Weather Statement	PHI	Cumberland	56 min
Apr 28, 12:38 PM EDT	Special Weather Statement	PHI	Hunterdon, Morris, Somerset	52 min
Apr 28, 1:13 PM EDT	Special Weather Statement	PHI	Atlantic, Cape May	62 min
Apr 28, 1:44 PM EDT	Special Marine Warning	PHI		91 min
Apr 28, 2:02 PM EDT	Severe Thunderstorm Warning	PHI	Atlantic, Burlington, Camden, Gloucester	41 min
Apr 28, 2:11 PM EDT	Areal Flood Advisory	PHI	Burlington, Monmouth, Ocean	94 min
Apr 28, 2:27 PM EDT	Severe Thunderstorm Warning	PHI	Burlington, Monmouth, Ocean	41 min
Apr 28, 2:42 PM EDT	Special Marine Warning	PHI		63 min
Apr 28, 2:55 PM EDT	Special Weather Statement	PHI	Monmouth	65 min
Apr 28, 5:04 PM EDT	Special Weather Statement	PHI	Cape May	56 min
Apr 28, 6:03 PM EDT	Special Marine Warning	PHI		57 min
Apr 28, 6:22 PM EDT	Special Weather Statement	PHI	Cape May	53 min
Apr 28, 6:37 PM EDT	Special Marine Warning	PHI		53 min
Apr 28, 11:32 AM EDT	Special Weather Statement	PHI	Kent	58 min
Apr 28, 11:37 AM EDT	Severe Thunderstorm Warning	PHI	Kent, New Castle	53 min
Apr 28, 5:38 PM EDT	Severe Thunderstorm Warning	PHI	Sussex	39 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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.