Alert archive / Pennsylvania / Severe Thunderstorm Warnings in 2002

Severe Thunderstorm Warning 78, NWS Philadelphia/Mount Holly

May 31, 2002Bucks County, Montgomery County, Philadelphia County, Pennsylvania

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at May 31, 2002, 5:30 PM EDT for Bucks County, Montgomery County, Philadelphia County, Pennsylvania. It was in force for 45 min. 5 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: May 31, 2002, 5:30 PM EDT (21:30 UTC)
Expired: May 31, 2002, 6:15 PM EDT
In force: 45 min
Issued by: NWS Philadelphia/Mount Holly
Area: Whole counties

Counties Bucks County, PA, Montgomery County, PA, Philadelphia County, PA

The radar

The Philadelphia radar (KDIX), 72 km from the middle of the area, began a volume at 21:32 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

Time	Report	Where
May 31, 5:30 PM EDT	Thunderstorm Wind 50 E	Warrington, PA
May 31, 5:30 PM EDT	Hail 0.75	Warminster, PA
May 31, 5:35 PM EDT	Thunderstorm Wind 52 E	Warminster, PA
May 31, 5:35 PM EDT	Thunderstorm Wind 50 E	Philadelphia, PA
May 31, 5:40 PM EDT	Hail 0.75	Southampton, PA

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 watch it was issued in

The SPC watch in force over the same counties when this warning went out.

Issued	Product	Office	Lasted
May 31, 5:15 PM EDT	Severe Thunderstorm Watch	SPC	6 hr

The nearest sounding before it

Brookhaven, NY (KOKX), launched 12:00Z, 9.5 hours before the alert went out and 212 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-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

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: 5 J/kg
Mixed-layer CIN: -130 J/kg
Mixed-layer LCL: 663 m above ground
0-6 km bulk shear: 21 kt
0-1 km storm-relative helicity: 45 m²/s²
0-3 km storm-relative helicity: 60 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

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

000 
WUUS51 KPHI 312130
SVRPHI
PAC017-091-101-312215-

BULLETIN - EAS ACTIVATION REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
530 PM EDT FRI MAY 31 2002

THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  SOUTHEASTERN BUCKS COUNTY IN SOUTHEAST PENNSYLVANIA.
  EAST CENTRAL MONTGOMERY COUNTY IN SOUTHEAST PENNSYLVANIA.
  EXTREME NORTHEASTERN PHILADELPHIA COUNTY IN SOUTHEAST PENNSYLVANIA.

* UNTIL 615 PM EDT.

* AT 527 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
  SEVERE THUNDERSTORM... OVER WILLOW GROVE...MOVING EAST AT 35 MPH.

* THE SEVERE THUNDERSTORM WILL BE NEAR...
  FEASTERVILLE...RICHBORO AT 535 PM.
  LANGHORNE...NEWTOWN AT 540 PM.
  LEVITTOWN...WOODSIDE AT 545 PM.

FOR THE LATEST STORM INFORMATION...PLEASE TUNE TO NOAA WEATHER
RADIO...YOUR LOCAL RADIO OR TELEVISION STATION...OR YOUR CABLE
TELEVISION OUTLET.

A SEVERE THUNDERSTORM WATCH REMAINS IN EFFECT UNTIL 1100 PM FRIDAY
EVENING FOR NORTHERN DELAWARE AND NORTHEAST MARYLAND AND NORTHWESTERN
NEW JERSEY AND EASTERN PENNSYLVANIA. A SEVERE THUNDERSTORM WATCH ALSO
REMAINS IN EFFECT UNTIL 800 PM FRIDAY EVENING FOR NORTHEAST
PENNSYLVANIA.

$$

LAT...LON 4022 7517 4008 7513 4012 7476 4025 7484

The office that day

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

Issued	Product	Office	Counties	Lasted
May 31, 4:31 PM EDT	Severe Thunderstorm Warning	PHI	Chester, Montgomery	29 min
May 31, 5:04 PM EDT	Severe Thunderstorm Warning	PHI	Bucks, Montgomery	26 min
May 31, 5:18 PM EDT	Severe Thunderstorm Warning	PHI	Monroe	27 min
May 31, 5:43 PM EDT	Severe Thunderstorm Warning	PHI	Monroe	47 min
May 31, 7:30 PM EDT	Severe Thunderstorm Warning	PHI	Northampton	45 min

Nearby

Severe Thunderstorm Warnings in Pennsylvania, 2002 Every severe thunderstorm warning in 2002

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; radar from the NEXRAD Level II archive.