Alert archive / Pennsylvania / Flash Flood Warnings in 1999
Flash Flood Warning 34, NWS Philadelphia/Mount Holly
NWS Philadelphia/Mount Holly issued this flash flood warning at Sep 16, 1999, 8:37 AM EDT for Chester County, Delaware County, Philadelphia County, Pennsylvania. It was in force for 4 hr. No storm report in the archive falls inside the area while it was in force.
The area
The counties it named.
The facts
- Issued
- Sep 16, 1999, 8:37 AM EDT (12:37 UTC)
- Expired
- Sep 16, 1999, 12:40 PM EDT
- In force
- 4 hr
- Issued by
- NWS Philadelphia/Mount Holly
- Area
- Whole counties
Counties Chester County, PA, Delaware County, PA, Philadelphia County, PA
The radar
The Philadelphia radar (KDIX), 87 km from the middle of the area, began a volume at 12:44 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 nearest sounding before it
Washington/Dulle, VA (KIAD), launched 12:00Z, 0.6 hours before the alert went out and 204 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
- 0 J/kg
- Mixed-layer CIN
- No buoyant parcel
- Mixed-layer LCL
- 577 m above ground
- 0-6 km bulk shear
- 50 kt
- 0-1 km storm-relative helicity
- 131 m²/s²
- 0-3 km storm-relative helicity
- 268 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted, in the capitals the NWS used until 2016.
000 TTAA00 KPHL 161238 FFWPHL PAC029-045-101-161640- BULLETIN - EAS ACTIVATION REQUESTED FLASH FLOOD WARNING NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 837 AM EDT THU SEP 16 1999 THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ HAS ISSUED A * FLASH FLOOD WARNING FOR... CHESTER COUNTY IN PENNSYLVANIA. DELAWARE COUNTY IN PENNSYLVANIA. PHILADELPHIA COUNTY IN PENNSYLVANIA. * UNTIL 1240 PM EDT. * AT 830 AM EDT HEAVY RAINS WERE FALLING OVER THE AREA. RAINFALL AMOUNTS IN EXCESS OF 2.00 INCHES HAVE FALLEN AND RADAR CONTINUES TO SHOW HEAVY RAIN MOVING INTO THE AREA. * AUTOMATIC RIVER GAGES IN THE AREA SHOW SMALL STREAMS RISING RAPIDLY. DO NOT DRIVE YOUR VEHICLE INTO AREAS WHERE THE WATER COVERS THE ROADWAY. THE WATER DEPTH MAY BE TOO GREAT TO ALLOW YOUR CAR TO CROSS SAFELY. VEHICLES CAUGHT IN RISING WATER SHOULD BE ABANDONED QUICKLY. 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 WN
The office that day
Everything else NWS Philadelphia/Mount Holly issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Sep 16, 9:25 AM EDT | Flash Flood Warning | PHI | Bucks, Montgomery | 6 hr |
| Sep 16, 11:25 AM EDT | Flash Flood Warning | PHI | Delaware, Philadelphia | 6 hr |
| Sep 16, 11:25 AM EDT | Flash Flood Warning | PHI | Chester | 6 hr |
| Sep 16, 12:11 PM EDT | Flash Flood Warning | PHI | Berks, Lehigh | 5 hr |
| Sep 16, 12:11 PM EDT | Flash Flood Warning | PHI | Northampton | 5 hr |
| Sep 16, 2:41 PM EDT | Flash Flood Warning | PHI | Bucks, Chester, Delaware, Montgomery, Philadelphia | 6 hr |
| Sep 16, 3:21 PM EDT | Flash Flood Warning | PHI | Carbon, Monroe | 6 hr |
| Sep 16, 4:21 PM EDT | Flash Flood Warning | PHI | Northampton | 5 hr |
| Sep 16, 4:21 PM EDT | Flash Flood Warning | PHI | Berks, Lehigh | 5 hr |
Nearby
Flash Flood Warnings in Pennsylvania, 1999Every flash flood 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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.