Alert archive / Pennsylvania / Severe Thunderstorm Warnings in 2001

Severe Thunderstorm Warning 37, NWS Philadelphia/Mount Holly

June 11, 2001Chester County, Delaware County, Pennsylvania; New Castle County, Delaware

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Jun 11, 2001, 10:22 PM EDT for Chester County, Delaware County, Pennsylvania; New Castle County, Delaware. It was in force for 53 min. 4 reports came from inside the area while it was in force.

The area

The counties it named, with what was reported inside it.

The facts

Issued
Jun 11, 2001, 10:22 PM EDT (02:22 UTC)
Expired
Jun 11, 2001, 11:15 PM EDT
In force
53 min
Issued by
NWS Philadelphia/Mount Holly
Area
Whole counties

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

What was reported inside it

TimeReportWhereRemark
Jun 11, 10:25 PM EDTThunderstorm Wind 50 EKennett Square, PA
Jun 11, 10:30 PM EDTThunderstorm Wind 50 ECountywide, PA
Jun 11, 10:30 PM EDTThunderstorm Wind 50 EYorklyn, DE
Jun 11, 10:35 PM EDTHail 0.88Wilmington, DE

NCEI Storm Data entries that began inside the alert's area while it was in force. Before 2003 the local storm report archive is thin, so this is the record of what happened rather than what was phoned in.

The nearest sounding before it

Washington/Dulle, VA (KIAD), launched 00:00Z, 2.4 hours before the alert went out and 183 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 2001-06-12Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 2046 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, Washington/Dulle, VA at 00:00Z on 2001-06-12The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 95 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
2046 J/kg
Mixed-layer CIN
-10 J/kg
Mixed-layer LCL
1306 m above ground
0-6 km bulk shear
33 kt
0-1 km storm-relative helicity
95 m²/s²
0-3 km storm-relative helicity
200 m²/s²
Significant tornado parameter
1.1
Supercell composite
10.2

Open this sounding in Storm Lab

The text

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

000 
WUUS51 KPHI 120222
SVRPHI
DEC003-PAC029-045-120315-

BULLETIN - EAS ACTIVATION REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
1022 PM EDT MON JUN 11 2001

THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ HAS ISSUED A

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

* UNTIL 1115 PM EDT.

* AT 1020 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED
  A SEVERE THUNDERSTORM NEAR KENNETT SQUARE...MOVING SOUTHEAST AT 15
  MPH.

* SOME LOCATIONS NEAR THE PATH OF THIS STORM INCLUDE...
  SWARTHMORE...
  KENNETT SQUARE...
  DREXEL HILL...
  WILMINGTON...
  TALLEYVILLE...
  ELSMERE...

LARGE HAIL...DAMAGING WINDS...AND HEAVY RAINFALL ARE LIKELY WITH THIS
STORM. TAKE COVER IN A STURDY BUILDING UNTIL THE STORM HAS PASSED.

$$

LAT...LON 3991 7578 3984 7582 3970 7555 3995 7528

IOVINO

The office that day

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

IssuedProductOfficeCountiesLasted
Jun 11, 9:00 PM EDTSevere Thunderstorm WarningPHIMonroe45 min
Jun 11, 10:15 PM EDTSevere Thunderstorm WarningPHIBucks45 min
Jun 12, 6:45 PM EDTSevere Thunderstorm WarningPHIBerks60 min

Nearby

Severe Thunderstorm Warnings in Pennsylvania, 2001Severe Thunderstorm Warnings in Delaware, 2001Every severe thunderstorm warning in 2001

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; verification from NCEI's Storm Data; the sounding from the Mesonet's radiosonde archive.