Alert archive / Pennsylvania / Severe Thunderstorm Warnings in 2008

Severe Thunderstorm Warning 233, NWS Philadelphia/Mount Holly

August 10, 2008Cecil County, Maryland; Chester County, Delaware County, Pennsylvania; New Castle County, Delaware

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Aug 10, 2008, 5:45 PM EDT for Cecil County, Maryland; Chester County, Delaware County, Pennsylvania; New Castle County, Delaware. It was in force for 75 min. 3 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 10, 2008, 5:45 PM EDT (21:45 UTC)
Expired
Aug 10, 2008, 7:00 PM EDT
In force
75 min
Issued by
NWS Philadelphia/Mount Holly
Area
Storm-based polygon

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

The radar

The Dover AFB radar (KDOX), 106 km from the middle of the area, began a volume at 21:45 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 10, 6:35 PM EDTHAIL 0.5Newark, DE
Aug 10, 6:41 PM EDTHAIL 0.25Newark, DE
Aug 10, 6:45 PM EDTHAIL 0.88Bear, DESTRONG WINDS

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 10, 10:46 AM EDTSevere Thunderstorm WatchSPC10 hr

The nearest sounding before it

Washington/Dulle, VA (KIAD), launched 12:00Z, 9.8 hours before the alert went out and 169 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 2008-08-10Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 771 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 2008-08-10The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 3 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
771 J/kg
Mixed-layer CIN
-66 J/kg
Mixed-layer LCL
923 m above ground
0-6 km bulk shear
25 kt
0-1 km storm-relative helicity
3 m²/s²
0-3 km storm-relative helicity
85 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.8

Open this sounding in Storm Lab

The text

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

000 
WUUS51 KPHI 102145
SVRPHI
DEC003-MDC015-PAC029-045-102300-
/O.NEW.KPHI.SV.W.0233.080810T2145Z-080810T2300Z/

BULLETIN - EAS ACTIVATION REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
545 PM EDT SUN AUG 10 2008

THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  NORTHERN CECIL COUNTY IN NORTHEAST MARYLAND...
  NORTHERN NEW CASTLE COUNTY IN NORTHERN DELAWARE...
  SOUTHERN CHESTER COUNTY IN SOUTHEAST PENNSYLVANIA...
  DELAWARE COUNTY IN SOUTHEAST PENNSYLVANIA...

* UNTIL 700 PM EDT

* AT 539 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 6 MILES
  NORTH OF LOMBARD...OR ABOUT 13 MILES NORTHWEST OF NEWARK...AND   
  MOVING EAST AT 18 MPH. ADDITIONAL STRONG THUNDERSTORMS WERE DEVELOPING 
  OVER NORTHEAST MARYLAND AND THEY TOO COULD BECOME SEVERE.

* THE SEVERE THUNDERSTORM WILL BE NEAR...
  WEST GROVE BY 600 PM...
  LADENBERG BY 605 PM...
  NORTH STAR BY 615 PM...
  KENNETT SQUARE AND HOCKESSIN BY 620 PM...
  ASHLAND BY 630 PM...
  TALLEYVILLE BY 645 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.

THIS STORM HAS A HISTORY OF PRODUCING DESTRUCTIVE WINDS AND LARGE
DAMAGING HAIL. SEEK SHELTER NOW INSIDE A STURDY STRUCTURE AND STAY
AWAY FROM WINDOWS

A SEVERE THUNDERSTORM WATCH REMAINS IN EFFECT UNTIL 700 PM SUNDAY
EVENING FOR DELAWARE AND NORTHEASTERN MARYLAND AND NEW JERSEY AND
EASTERN PENNSYLVANIA.

LAT...LON 3975 7604 4002 7553 3999 7532 3965 7556
      3965 7559 3957 7562 3963 7617
TIME...MOT...LOC 2144Z 262DEG 16KT 3981 7591

$$

RNS
1 follow-up statement
000 
WWUS51 KPHI 102231
SVSPHI

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
631 PM EDT SUN AUG 10 2008

DEC003-MDC015-PAC029-045-102300-
/O.CON.KPHI.SV.W.0233.000000T0000Z-080810T2300Z/
CECIL MD-DELAWARE PA-CHESTER PA-NEW CASTLE DE-
631 PM EDT SUN AUG 10 2008

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 700 PM EDT
FOR NORTHERN NEW CASTLE...SOUTH CENTRAL CHESTER...DELAWARE AND
NORTHEASTERN CECIL COUNTIES...

AT 626 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR CONTINUED TO
INDICATE A SEVERE THUNDERSTORM CAPABLE OF PRODUCING NICKEL SIZE
HAIL...AND DAMAGING WINDS IN EXCESS OF 60 MPH.  THIS STORM WAS
LOCATED NEAR WILMINGTON...MOVING EAST AT 27 MPH. ANOTHER STORM WAS L
OVER CECIL COUNTY MARYLAND AND THAT STORM WILL MOVE INTO NEW CASTLE
COUNTY DELAWARE THROUGH 700 PM.

THE SEVERE THUNDERSTORM WILL BE NEAR...
  CLAYMONT...6 MILES SOUTH OF BOOTHWYN AND 9 MILES SOUTH OF CHELSEA
  BY 640 PM EDT...
  8 MILES SOUTH OF VILLAGE GREEN-GREEN RIDGE BY 645 PM EDT...

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 700 PM EDT SUNDAY
EVENING FOR DELAWARE AND NORTHEASTERN MARYLAND AND NEW JERSEY AND
EASTERN PENNSYLVANIA.

LAT...LON 3986 7565 4000 7535 3999 7532 3965 7556
      3965 7559 3957 7561 3961 7599
TIME...MOT...LOC 2231Z 265DEG 23KT 3974 7551

$$

RNS

The office that day

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

IssuedProductOfficeCountiesLasted
Aug 10, 5:59 PM EDTAreal Flood AdvisoryPHICecil2 hr
Aug 10, 6:14 PM EDTSevere Thunderstorm WarningPHICecil, Kent61 min
Aug 10, 6:36 PM EDTSevere Thunderstorm WarningPHICecil69 min
Aug 10, 10:18 AM EDTSevere Thunderstorm WarningPHIChester57 min
Aug 10, 10:44 AM EDTSevere Thunderstorm WarningPHIDelaware61 min
Aug 10, 11:09 AM EDTSevere Thunderstorm WarningPHIChester, Delaware, Montgomery, Philadelphia66 min
Aug 10, 11:32 AM EDTAreal Flood AdvisoryPHIChester, Delaware3 hr
Aug 10, 11:46 AM EDTSevere Thunderstorm WarningPHIDelaware59 min
Aug 10, 12:09 PM EDTTornado WarningPHIDelaware36 min
Aug 10, 12:17 PM EDTFlash Flood WarningPHIChester, Delaware, Montgomery4 hr
Aug 10, 12:21 PM EDTSevere Thunderstorm WarningPHIBerks, Bucks, Lehigh, Montgomery84 min
Aug 10, 12:40 PM EDTSevere Thunderstorm WarningPHIDelaware, Philadelphia95 min
Aug 10, 1:05 PM EDTSevere Thunderstorm WarningPHIBucks, Carbon, Lehigh, Monroe, Northampton115 min
Aug 10, 1:10 PM EDTSevere Thunderstorm WarningPHIBerks, Chester, Montgomery65 min
Aug 10, 1:47 PM EDTSevere Thunderstorm WarningPHIChester, Montgomery58 min
Aug 10, 3:05 PM EDTFlash Flood WarningPHIChester3 hr
Aug 10, 3:35 PM EDTSevere Thunderstorm WarningPHIBerks40 min
Aug 10, 4:45 PM EDTSevere Thunderstorm WarningPHIChester75 min
Aug 10, 5:25 PM EDTAreal Flood AdvisoryPHIBerks, Montgomery110 min
Aug 10, 6:45 PM EDTAreal Flood AdvisoryPHIPhiladelphia2 hr
Aug 10, 10:21 AM EDTSevere Thunderstorm WarningPHINew Castle54 min
Aug 10, 12:03 PM EDTSevere Thunderstorm WarningPHISussex57 min
Aug 10, 7:09 PM EDTSevere Thunderstorm WarningPHINew Castle66 min

Nearby

Severe Thunderstorm Warnings in Pennsylvania, 2008Severe Thunderstorm Warnings in Maryland, 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; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.