Alert archive / Pennsylvania / Severe Thunderstorm Warnings in 2008

Severe Thunderstorm Warning 225, NWS Philadelphia/Mount Holly

August 10, 2008Chester County, Montgomery County, Pennsylvania

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Aug 10, 2008, 1:47 PM EDT for Chester County, Montgomery County, Pennsylvania. It was in force for 58 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 10, 2008, 1:47 PM EDT (17:47 UTC)
Expired
Aug 10, 2008, 2:45 PM EDT
In force
58 min
Issued by
NWS Philadelphia/Mount Holly
Area
Storm-based polygon

Counties Chester County, PA, Montgomery County, PA

The radar

The Philadelphia radar (KDIX), 115 km from the middle of the area, began a volume at 17:46 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 10, 10:46 AM EDTSevere Thunderstorm WatchSPC10 hr

The nearest sounding before it

Washington/Dulle, VA (KIAD), launched 12:00Z, 5.8 hours before the alert went out and 185 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 101747
SVRPHI
PAC029-091-101845-
/O.NEW.KPHI.SV.W.0225.080810T1747Z-080810T1845Z/

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

THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ HAS ISSUED A

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

* UNTIL 245 PM EDT

* AT 142 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
  SEVERE THUNDERSTORM CAPABLE OF PRODUCING QUARTER SIZE HAIL...AND
  DAMAGING WINDS IN EXCESS OF 60 MPH.  THIS STORM WAS LOCATED NEAR
  GLENMOORE...OR ABOUT 14 MILES NORTHWEST OF WEST CHESTER...AND
  MOVING NORTHEAST AT 22 MPH.

* THE SEVERE THUNDERSTORM WILL BE NEAR...
  PUGHTOWN AND CHESTER SPRINGS BY 205 PM...
  CEDARVILLE BY 210 PM...
  PHOENIXVILLE BY 220 PM...
  COLLEGEVILLE BY 230 PM...
  SPRING MOUNT BY 240 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 700 PM SUNDAY
EVENING FOR DELAWARE AND NORTHEASTERN MARYLAND AND NEW JERSEY AND
EASTERN PENNSYLVANIA.

LAT...LON 3988 7600 3996 7601 4013 7591 4024 7571
      4036 7561 4042 7552 4023 7521 3995 7554
      3983 7570 3974 7578 3972 7613
TIME...MOT...LOC 1748Z 242DEG 19KT 4011 7575

$$

RNS

The office that day

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

IssuedProductOfficeCountiesLasted
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, 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, 5:45 PM EDTSevere Thunderstorm WarningPHIChester, Delaware75 min
Aug 10, 5:59 PM EDTAreal Flood AdvisoryPHIChester, Delaware2 hr
Aug 10, 6:45 PM EDTAreal Flood AdvisoryPHIPhiladelphia2 hr

Nearby

Severe 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.