Alert archive / Pennsylvania / Severe Thunderstorm Warnings in 2007

Severe Thunderstorm Warning 238, NWS Philadelphia/Mount Holly

October 19, 2007Chester County, Pennsylvania

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Oct 19, 2007, 9:18 PM EDT for Chester County, Pennsylvania. It was in force for 27 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
Oct 19, 2007, 9:18 PM EDT (01:18 UTC)
Expired
Oct 19, 2007, 9:45 PM EDT
In force
27 min
Issued by
NWS Philadelphia/Mount Holly
Area
Storm-based polygon

County Chester County, PA

The radar

The Philadelphia radar (KDIX), 104 km from the middle of the area, began a volume at 01:19 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 nearest sounding before it

Washington/Dulle, VA (KIAD), launched 00:00Z, 1.3 hours before the alert went out and 201 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 2007-10-20Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 480 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, Washington/Dulle, VA at 00:00Z on 2007-10-20The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 98 square meters per square second.1939587897117Sfc1 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
480 J/kg
Mixed-layer CIN
-17 J/kg
Mixed-layer LCL
682 m above ground
0-6 km bulk shear
53 kt
0-1 km storm-relative helicity
98 m²/s²
0-3 km storm-relative helicity
186 m²/s²
Significant tornado parameter
0.3
Supercell composite
1.3

Open this sounding in Storm Lab

The text

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

000 
WUUS51 KPHI 200118
SVRPHI
PAC029-200145-
/O.NEW.KPHI.SV.W.0238.071020T0118Z-071020T0145Z/

BULLETIN - EAS ACTIVATION REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
918 PM EDT FRI OCT 19 2007

THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  NORTHEASTERN CHESTER COUNTY IN SOUTHEAST PENNSYLVANIA...

* UNTIL 945 PM EDT

* AT 917 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
  SEVERE THUNDERSTORM CAPABLE OF PRODUCING DAMAGING WINDS IN EXCESS
  OF 60 MPH.  THIS STORM WAS LOCATED NEAR DOWNINGTOWN...OR ABOUT 22
  MILES NORTH OF NEWARK...AND MOVING NORTHEAST AT 50 MPH.

* THE SEVERE THUNDERSTORM WILL BE NEAR...
  LIONVILLE AND DOWNINGTOWN BY 925 PM EDT...
  CHESTER SPRINGS AND 6 MILES SOUTHEAST OF PUGHTOWN BY 930 PM EDT...
  PHOENIXVILLE AND VALLEY FORGE BY 940 PM EDT...

THUNDERSTORMS ARE CAPABLE OF PRODUCING HEAVY RAINFALL WHICH MAY
RESULT IN LOCALIZED AREAS OF FLOODING. DO NOT DRIVE IN AREAS WHERE
WATER IS CROSSING THE ROAD.

LAT...LON 4023 7564 4014 7551 4012 7551 4012 7549
      4007 7542 3994 7579 4007 7586
TIME...MOT...LOC 0118Z 237DEG 44KT 4000 7579

$$

 
TFG

The office that day

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

IssuedProductOfficeCountiesLasted
Oct 19, 8:33 PM EDTSevere Thunderstorm WarningPHIBerks35 min
Oct 19, 8:55 PM EDTSevere Thunderstorm WarningPHIChester33 min

Nearby

Severe Thunderstorm Warnings in Pennsylvania, 2007Every severe thunderstorm warning in 2007

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.