Alert archive / Pennsylvania / Severe Thunderstorm Warnings in 2004

Severe Thunderstorm Warning 163, NWS Philadelphia/Mount Holly

August 11, 2004Bucks County, Pennsylvania

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Aug 11, 2004, 2:21 PM EDT for Bucks County, Pennsylvania. It was in force for 54 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
Aug 11, 2004, 2:21 PM EDT (18:21 UTC)
Expired
Aug 11, 2004, 3:15 PM EDT
In force
54 min
Issued by
NWS Philadelphia/Mount Holly
Area
Counties, with a storm outline in the text

County Bucks County, PA

The radar

The Philadelphia radar (KDIX), 61 km from the middle of the area, began a volume at 18:23 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.

IssuedProductOfficeLasted
Aug 11, 12:55 PM EDTSevere Thunderstorm WatchSPC7 hr

The nearest sounding before it

Brookhaven, NY (KOKX), launched 12:00Z, 6.4 hours before the alert went out and 188 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 12:00Z on 2004-08-11Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1077 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 12:00Z on 2004-08-11The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 72 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
1077 J/kg
Mixed-layer CIN
-31 J/kg
Mixed-layer LCL
599 m above ground
0-6 km bulk shear
25 kt
0-1 km storm-relative helicity
72 m²/s²
0-3 km storm-relative helicity
130 m²/s²
Significant tornado parameter
0.3
Supercell composite
1.2

Open this sounding in Storm Lab

The text

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

000 
WUUS51 KPHI 111821
SVRPHI
PAC017-111915-

BULLETIN - EAS ACTIVATION REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
220 PM EDT WED AUG 11 2004

THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  BUCKS COUNTY IN SOUTHEAST PENNSYLVANIA.

* UNTIL 315 PM EDT

* AT 218 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
  SEVERE THUNDERSTORM CAPABLE OF PRODUCING NICKEL SIZE HAIL...AND
  DAMAGING WINDS IN EXCESS OF 60 MPH.  THIS STORM WAS LOCATED NEAR
  CHALFONT...OR ABOUT 15 MILES NORTH OF PHILADELPHIA...AND MOVING
  NORTHEAST AT 20 MPH.

* THE SEVERE THUNDERSTORM WILL BE NEAR...
  IVYLAND BY 230 PM EDT...
  DOYLESTOWN BY 235 PM EDT...
  RICHBORO BY 240 PM EDT...
  6 MILES NORTHWEST OF NEWTOWN BY 255 PM EDT...
  NEW HOPE BY 300 PM EDT...
  7 MILES NORTHWEST OF WOODSIDE BY 305 PM EDT...

IN ADDITION ANOTHER VERY STRONG STORM WAS LOCATED JUST EAST OF 
DOYLESTOWN AND THIS TOO MIGHT PRODUCE DAMAGING WINDS AND LARGE HAIL.


LAT...LON 4032 7493 4030 7488 4027 7486 4025 7486
      4023 7481 4016 7506 4030 7527 4040 7500
      4040 7498

$$

TFG

The office that day

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

IssuedProductOfficeCountiesLasted
Aug 11, 2:40 PM EDTSevere Thunderstorm WarningPHIChester95 min
Aug 11, 3:12 PM EDTTornado WarningPHIChester78 min
Aug 11, 4:04 PM EDTSevere Thunderstorm WarningPHIBucks41 min
Aug 11, 5:09 PM EDTSpecial Marine WarningPHI81 min
Aug 11, 5:25 PM EDTSevere Thunderstorm WarningPHIBerks65 min
Aug 11, 5:28 PM EDTSevere Thunderstorm WarningPHIPhiladelphia32 min
Aug 11, 5:37 PM EDTSevere Thunderstorm WarningPHIBucks53 min
Aug 11, 5:56 PM EDTSevere Thunderstorm WarningPHIMontgomery34 min

Nearby

Severe Thunderstorm Warnings in Pennsylvania, 2004Every severe thunderstorm warning in 2004

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.