Alert archive / Pennsylvania / Severe Thunderstorm Warnings in 2008

Severe Thunderstorm Warning 151, NWS Philadelphia/Mount Holly

July 23, 2008Chester County, Delaware County, Pennsylvania; New Castle County, Delaware

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Jul 23, 2008, 4:27 PM EDT for Chester County, Delaware County, Pennsylvania; New Castle County, Delaware. It was in force for 38 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
Jul 23, 2008, 4:27 PM EDT (20:27 UTC)
Expired
Jul 23, 2008, 5:05 PM EDT
In force
38 min
Issued by
NWS Philadelphia/Mount Holly
Area
Storm-based polygon

Counties New Castle County, DE, Chester County, PA, Delaware County, PA

The radar

The Philadelphia radar (KDIX), 115 km from the middle of the area, began a volume at 20:27 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
Jul 23, 2:34 PM EDTSevere Thunderstorm WatchSPC7 hr

The nearest sounding before it

Phillips Aaf/Abe, MD (KAPG), launched 12:00Z, 8.5 hours before the alert went out and 62 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 2008-07-23Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1012 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, Phillips Aaf/Abe, MD at 12:00Z on 2008-07-23The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -61 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
1012 J/kg
Mixed-layer CIN
-98 J/kg
Mixed-layer LCL
980 m above ground
0-6 km bulk shear
43 kt
0-1 km storm-relative helicity
-61 m²/s²
0-3 km storm-relative helicity
-48 m²/s²
Significant tornado parameter
-0.4
Supercell composite
-7.5

Open this sounding in Storm Lab

The text

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

000 
WUUS51 KPHI 232028
SVRPHI
DEC003-PAC029-045-232130-
/O.NEW.KPHI.SV.W.0151.080723T2027Z-080723T2130Z/

BULLETIN - EAS ACTIVATION REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
427 PM EDT WED JUL 23 2008

THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  NORTHWESTERN NEW CASTLE COUNTY IN NORTHERN DELAWARE...
  CENTRAL CHESTER COUNTY IN SOUTHEAST PENNSYLVANIA...
  SOUTHWESTERN DELAWARE COUNTY IN SOUTHEAST PENNSYLVANIA...

* UNTIL 530 PM EDT

* AT 425 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 
  KEMBLESVILLE...AND MOVING NORTH AT 25 MPH.

* THE SEVERE THUNDERSTORM WILL BE NEAR...
  WEST GROVE AND ASHLAND BY 435 PM...
  KENNETT SQUARE BY 440 PM...
  MARSHALLTON...COATESVILLE AND WEST CHESTER BY 500 PM...
  DOWNINGTOWN BY 510 PM...
  GLENMOORE AND LIONVILLE BY 520 PM...
  CHESTER SPRINGS BY 525 PM...

IN ADDITION TO LARGE HAIL 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.

A SEVERE THUNDERSTORM WATCH REMAINS IN EFFECT UNTIL 1000 PM WEDNESDAY
EVENING FOR DELAWARE AND NORTHEASTERN MARYLAND AND NEW JERSEY AND
SOUTHEAST PENNSYLVANIA.

LAT...LON 4013 7589 4008 7550 3972 7561 3973 7591
TIME...MOT...LOC 2027Z 192DEG 20KT 3978 7580

$$

IOVINO
1 follow-up statement
000 
WWUS51 KPHI 232105
SVSPHI

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
505 PM EDT WED JUL 23 2008

DEC003-PAC029-045-232115-
/O.CAN.KPHI.SV.W.0151.000000T0000Z-080723T2130Z/
DELAWARE PA-CHESTER PA-NEW CASTLE DE-
505 PM EDT WED JUL 23 2008

...THE SEVERE THUNDERSTORM WARNING FOR NORTHWESTERN NEW CASTLE...
CENTRAL CHESTER AND SOUTHWESTERN DELAWARE COUNTIES IS CANCELLED...

THE THUNDERSTORM THAT PROMPTED THE WARNING TO BE ISSUED HAS WEAKENED.
THE SEVERE THUNDERSTORM WARNING IS CANCELLED.

A SEVERE THUNDERSTORM WATCH REMAINS IN EFFECT UNTIL 1000 PM EDT
WEDNESDAY EVENING FOR DELAWARE AND NORTHEASTERN MARYLAND AND NEW
JERSEY AND SOUTHEAST PENNSYLVANIA.

LAT...LON 4013 7589 4008 7550 3972 7561 3973 7591
TIME...MOT...LOC 2105Z 192DEG 20KT 3999 7574

$$

IOVINO

The office that day

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

IssuedProductOfficeCountiesLasted
Jul 23, 3:51 AM EDTFlash Flood WatchPHIBerks, Carbon, Delaware, Lehigh, Monroe, Northampton and 1 more25 hr
Jul 23, 4:23 AM EDTAreal Flood AdvisoryPHIBucks, Chester, Montgomery3 hr
Jul 23, 2:55 PM EDTSevere Thunderstorm WarningPHIBucks35 min
Jul 23, 2:58 PM EDTSevere Thunderstorm WarningPHIBucks47 min
Jul 23, 3:30 PM EDTSevere Thunderstorm WarningPHIDelaware, Philadelphia60 min
Jul 23, 3:58 PM EDTSevere Thunderstorm WarningPHIChester, Delaware, Montgomery62 min
Jul 23, 4:47 PM EDTSevere Thunderstorm WarningPHIBerks, Bucks, Lehigh, Montgomery, Northampton58 min
Jul 23, 5:03 PM EDTSevere Thunderstorm WarningPHIBucks57 min
Jul 23, 5:13 PM EDTSevere Thunderstorm WarningPHIBucks62 min
Jul 23, 7:00 PM EDTSevere Thunderstorm WarningPHIDelaware60 min
Jul 23, 7:48 PM EDTSevere Thunderstorm WarningPHIBucks, Delaware, Montgomery, Philadelphia57 min
Jul 23, 1:11 AM EDTSevere Thunderstorm WarningPHINew Castle64 min
Jul 23, 6:11 PM EDTSevere Thunderstorm WarningPHIKent64 min

Nearby

Severe Thunderstorm Warnings in Pennsylvania, 2008Severe Thunderstorm Warnings in Delaware, 2008Every severe thunderstorm warning in 2008

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.