Alert archive / Pennsylvania / Severe Thunderstorm Warnings in 2006

Severe Thunderstorm Warning 262, NWS Philadelphia/Mount Holly

August 29, 20064 counties in Pennsylvania

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Aug 29, 2006, 3:37 PM EDT for 4 counties in Pennsylvania. It was in force for 68 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
Aug 29, 2006, 3:37 PM EDT (19:37 UTC)
Expired
Aug 29, 2006, 4:45 PM EDT
In force
68 min
Issued by
NWS Philadelphia/Mount Holly
Area
Counties, with a storm outline in the text

Counties Chester County, PA, Delaware County, PA, Montgomery County, PA, Philadelphia County, PA

The radar

The Philadelphia radar (KDIX), 81 km from the middle of the area, began a volume at 19:38 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
Aug 29, 3:47 PM EDTTSTM WND DMGPhiladelphia, PATREE KNOCKED DOWN IN SOUTH PHILADELPHIA.
Aug 29, 4:37 PM EDTTSTM WND DMG5 Sw Phoenixville, PAWIRES REPORTED DOWN IN CHARLESTOWN TOWNSHIP.

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
Aug 29, 1:52 PM EDTTornado WatchSPC6 hr

The nearest sounding before it

Phillips Aaf/Abe, MD (KAPG), launched 12:00Z, 7.6 hours before the alert went out and 95 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, Phillips Aaf/Abe, MD at 12:00Z on 2006-08-29Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 21 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Phillips Aaf/Abe, MD at 12:00Z on 2006-08-29The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 98 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
21 J/kg
Mixed-layer CIN
-132 J/kg
Mixed-layer LCL
934 m above ground
0-6 km bulk shear
40 kt
0-1 km storm-relative helicity
98 m²/s²
0-3 km storm-relative helicity
185 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.2

Open this sounding in Storm Lab

The text

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

000 
WUUS51 KPHI 291938
SVRPHI
PAC029-045-091-101-292045-
/O.NEW.KPHI.SV.W.0262.060829T1937Z-060829T2045Z/

BULLETIN - EAS ACTIVATION REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
337 PM EDT TUE AUG 29 2006

THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  NORTHEASTERN CHESTER COUNTY IN SOUTHEAST PENNSYLVANIA
  NORTHEASTERN DELAWARE COUNTY IN SOUTHEAST PENNSYLVANIA
  SOUTHERN MONTGOMERY COUNTY IN SOUTHEAST PENNSYLVANIA
  NORTHERN PHILADELPHIA COUNTY IN SOUTHEAST PENNSYLVANIA
  THIS INCLUDES THE CITY OF PHILADELPHIA

* UNTIL 445 PM EDT

* AT 334 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
  LINE OF SEVERE THUNDERSTORMS CAPABLE OF PRODUCING PENNY SIZE
  HAIL...AND DAMAGING WINDS IN EXCESS OF 60 MPH.  THESE STORMS WERE
  LOCATED ALONG A LINE EXTENDING FROM COLLEGEVILLE TO 9 MILES WEST OF
  DOWNINGTOWN...AND MOVING EAST AT 25 MPH.

* SEVERE THUNDERSTORMS WILL BE NEAR...
  LIONVILLE AND DOWNINGTOWN BY 350 PM EDT...
  NORRISTOWN BY 400 PM EDT...
  PAOLI...KING OF PRUSSIA AND AMBLER BY 405 PM EDT...
  PLYMOUTH MEETING BY 410 PM EDT...
  WILLOW GROVE AND RADNOR TOWNSHIP BY 415 PM EDT...
  CHESTNUT HILL BY 420 PM EDT...

DOPPLER RADAR HAS INDICATED SOME WEAK ROTATION WITHIN THIS STORM
IN NORTHERN CHESTER COUNTY. WHILE NOT IMMEDIATELY LIKELY...A 
TORNADO MAY STILL DEVELOP. IF A TORNADO IS SPOTTED...ACT QUICKLY 
AND MOVE TO A PLACE OF SAFETY IN A STURDY STRUCTURE...SUCH AS A 
BASEMENT OR SMALL INTERIOR ROOM.

IN ADDITION TO LARGE HAIL...TORRENTIAL DOWNPOURS AND DAMAGING 
WINDS...CONTINUOUS CLOUD TO GROUND LIGHTNING IS OCCURRING 
WITH THIS STORM. MOVE INDOORS IMMEDIATELY LIGHTNING IS 
ONE OF NATURES NUMBER ONE KILLERS. REMEMBER...IF YOU CAN 
HEAR THUNDER...YOU ARE CLOSE ENOUGH TO BE
STRUCK BY LIGHTNING.

LAT...LON 4025 7544 4002 7586 3991 7529 4001 7504
      4011 7498

$$

TFG

The office that day

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

IssuedProductOfficeCountiesLasted
Aug 29, 2:14 PM EDTSevere Thunderstorm WarningPHIBerks61 min
Aug 29, 2:42 PM EDTFlash Flood WarningPHIBerks3 hr
Aug 29, 2:53 PM EDTSevere Thunderstorm WarningPHIChester, Montgomery52 min
Aug 29, 3:39 PM EDTFlash Flood WarningPHIChester3 hr
Aug 29, 3:50 PM EDTFlash Flood WarningPHIMontgomery3 hr
Aug 29, 4:15 PM EDTFlash Flood WarningPHIPhiladelphia3 hr
Aug 29, 5:43 PM EDTFlash Flood WarningPHIBerks2 hr

Nearby

Severe Thunderstorm Warnings in Pennsylvania, 2006Every severe thunderstorm warning in 2006

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.