Alert archive / Delaware / Severe Thunderstorm Warnings in 2008

Severe Thunderstorm Warning 171, NWS Philadelphia/Mount Holly

July 27, 2008New Castle County, Delaware; Chester County, Pennsylvania

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Jul 27, 2008, 12:57 PM EDT for New Castle County, Delaware; Chester County, Pennsylvania. It was in force for 63 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 27, 2008, 12:57 PM EDT (16:57 UTC)
Expired
Jul 27, 2008, 2:00 PM EDT
In force
63 min
Issued by
NWS Philadelphia/Mount Holly
Area
Storm-based polygon

Counties New Castle County, DE, Chester County, PA

The radar

The Dover AFB radar (KDOX), 121 km from the middle of the area, began a volume at 16:57 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 27, 11:26 AM EDTSevere Thunderstorm WatchSPC8 hr

The nearest sounding before it

Washington/Dulle, VA (KIAD), launched 12:00Z, 5.0 hours before the alert went out and 159 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 12:00Z on 2008-07-27Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1356 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 12:00Z on 2008-07-27The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -17 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
1356 J/kg
Mixed-layer CIN
-70 J/kg
Mixed-layer LCL
1062 m above ground
0-6 km bulk shear
32 kt
0-1 km storm-relative helicity
-17 m²/s²
0-3 km storm-relative helicity
63 m²/s²
Significant tornado parameter
0.1
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 271658
SVRPHI
DEC003-PAC029-271800-
/O.NEW.KPHI.SV.W.0171.080727T1657Z-080727T1800Z/

BULLETIN - EAS ACTIVATION REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
1257 PM EDT SUN JUL 27 2008

THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ HAS ISSUED A

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

* UNTIL 200 PM EDT

* AT 1255 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
  MOUNT VERNON...AND MOVING EAST AT 22 MPH.

* THE SEVERE THUNDERSTORM WILL BE NEAR...
  COCHRANVILLE BY 110 PM...
  WEST GROVE BY 120 PM...
  LADENBERG BY 130 PM...
  KENNETT SQUARE AND HOCKESSIN BY 140 PM...
  ASHLAND BY 145 PM...
  MARSHALLTON BY 150 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 800 PM SUNDAY
EVENING FOR DELAWARE AND NORTHEASTERN MARYLAND AND NEW JERSEY AND
EASTERN PENNSYLVANIA.

LAT...LON 3981 7605 3986 7602 3988 7600 3989 7601
      3990 7601 4003 7566 3972 7559 3973 7605
      3981 7606
TIME...MOT...LOC 1657Z 259DEG 18KT 3982 7599

$$

IOVINO

The office that day

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

IssuedProductOfficeCountiesLasted
Jul 27, 2:00 PM EDTSevere Thunderstorm WarningPHINew Castle60 min
Jul 27, 2:17 PM EDTSevere Thunderstorm WarningPHINew Castle58 min
Jul 27, 2:31 PM EDTSevere Thunderstorm WarningPHIKent, New Castle59 min
Jul 27, 2:35 PM EDTSevere Thunderstorm WarningPHIKent, Sussex55 min
Jul 27, 3:38 PM EDTSevere Thunderstorm WarningPHIKent, Sussex54 min
Jul 27, 11:50 AM EDTSevere Thunderstorm WarningPHIBerks, Carbon, Lehigh, Monroe, Northampton70 min
Jul 27, 12:07 PM EDTSevere Thunderstorm WarningPHIChester53 min
Jul 27, 12:19 PM EDTSevere Thunderstorm WarningPHIBerks, Chester, Lehigh, Montgomery56 min
Jul 27, 12:25 PM EDTAreal Flood AdvisoryPHIBerks, Bucks, Chester, Lehigh, Montgomery3 hr
Jul 27, 12:38 PM EDTSevere Thunderstorm WarningPHIChester67 min
Jul 27, 12:50 PM EDTAreal Flood AdvisoryPHIBucks, Chester, Montgomery3 hr
Jul 27, 1:00 PM EDTSevere Thunderstorm WarningPHIBucks, Montgomery60 min
Jul 27, 1:34 PM EDTFlash Flood WarningPHIChester3 hr
Jul 27, 1:44 PM EDTSevere Thunderstorm WarningPHIBucks, Montgomery61 min
Jul 27, 2:11 PM EDTSevere Thunderstorm WarningPHIBucks64 min
Jul 27, 2:14 PM EDTSevere Thunderstorm WarningPHIBucks, Philadelphia61 min
Jul 27, 2:30 PM EDTAreal Flood AdvisoryPHIBucks2 hr
Jul 27, 5:04 PM EDTSevere Thunderstorm WarningPHIBerks, Chester56 min
Jul 27, 6:44 PM EDTAreal Flood AdvisoryPHIChester72 min

Nearby

Severe Thunderstorm Warnings in Delaware, 2008Severe Thunderstorm Warnings in Pennsylvania, 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.