Alert archive / Pennsylvania / Severe Thunderstorm Warnings in 1999
Severe Thunderstorm Warning 57, NWS Philadelphia/Mount Holly
NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Aug 14, 1999, 4:54 PM EDT for Delaware County, Philadelphia County, Pennsylvania. It was in force for 46 min. 2 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
- Aug 14, 1999, 4:54 PM EDT (20:54 UTC)
- Expired
- Aug 14, 1999, 5:40 PM EDT
- In force
- 46 min
- Issued by
- NWS Philadelphia/Mount Holly
- Area
- Whole counties
Counties Delaware County, PA, Philadelphia County, PA
The radar
The Philadelphia radar (KDIX), 73 km from the middle of the area, began a volume at 20:57 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.
What was reported inside it
| Time | Report | Where | Remark |
|---|---|---|---|
| Aug 14, 4:55 PM EDT | Thunderstorm Wind | Countywide, PA | |
| Aug 14, 5:05 PM EDT | Thunderstorm Wind | Countywide, 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 nearest sounding before it
Washington/Dulle, VA (KIAD), launched 12:00Z, 8.9 hours before the alert went out and 215 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.
- Mixed-layer CAPE
- 379 J/kg
- Mixed-layer CIN
- -157 J/kg
- Mixed-layer LCL
- 930 m above ground
- 0-6 km bulk shear
- 29 kt
- 0-1 km storm-relative helicity
- -56 m²/s²
- 0-3 km storm-relative helicity
- 22 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- -1.8
The text
As transmitted, in the capitals the NWS used until 2016.
000 TTAA00 KPHL 142057 RRA SVRPHL PAC045-101-142140- BULLETIN - EAS ACTIVATION REQUESTED SEVERE THUNDERSTORM WARNING NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 454 PM EDT SAT AUG 14 1999 THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ HAS ISSUED A * SEVERE THUNDERSTORM WARNING FOR... DELAWARE COUNTY IN PENNSYLVANIA. PHILADELPHIA COUNTY IN PENNSYLVANIA. * UNTIL 540 PM EDT. * AT 452 PM EDT... NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A SEVERE THUNDERSTORM IN THE VICINITY OF BROOMALL... MOVING EAST AT 30 MPH. * THE SEVERE THUNDERSTORM IS EXPECTED TO BE NEAR... DARBY AT 500 PM EDT. MANAYUNK AT 505 PM EDT. WEST PHILADELPHIA AT 510 PM EDT. CENTER CITY PHILADELPHIA AT 510 PM EDT. THIS IS A DANGEROUS STORM. MOVE INSIDE A STRONG BUILDING AND DO NOT STAND NEAR WINDOWS. FOR YOUR PROTECTION MOVE TO AN INTERIOR ROOM ON THE LOWEST FLOOR OF YOUR HOME OR BUSINESS. DO NOT DRIVE YOUR CAR WHERE WATER COVERS THE ROADWAY. THE WATER MAY BE DEEPER THAN YOU THINK. IF CAUGHT IN RISING FLOOD WATERS... ABANDON YOUR CAR QUICKLY AND MOVE TO HIGHER GROUND. FOR THE LATEST STORM INFORMATION...PLEASE TUNE TO NOAA WEATHER RADIO...YOUR LOCAL RADIO OR TELEVISION STATIONS...OR YOUR CABLE TELEVISION OUTLET. .END GS/DI
The office that day
Everything else NWS Philadelphia/Mount Holly issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 13, 8:54 PM EDT | Severe Thunderstorm Warning | PHI | Carbon, Monroe | 46 min |
| Aug 13, 9:42 PM EDT | Severe Thunderstorm Warning | PHI | Carbon | 33 min |
| Aug 13, 9:54 PM EDT | Severe Thunderstorm Warning | PHI | Monroe, Northampton | 61 min |
| Aug 13, 10:29 PM EDT | Severe Thunderstorm Warning | PHI | Berks | 61 min |
| Aug 14, 2:14 AM EDT | Flash Flood Warning | PHI | Bucks | 3 hr |
| Aug 14, 5:19 PM EDT | Severe Thunderstorm Warning | PHI | Bucks | 51 min |
Nearby
Severe Thunderstorm Warnings in Pennsylvania, 1999Every severe thunderstorm warning in 1999
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.