Alert archive / Pennsylvania / Flash Flood Warnings in 1999

Flash Flood Warning 48, NWS Philadelphia/Mount Holly

September 16, 19995 counties in Pennsylvania

NWS Philadelphia/Mount Holly issued this flash flood warning at Sep 16, 1999, 2:41 PM EDT for 5 counties in Pennsylvania. It was in force for 6 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, 2:41 PM EDT (18:41 UTC)
Expired
Sep 16, 1999, 8:35 PM EDT
In force
6 hr
Issued by
NWS Philadelphia/Mount Holly
Area
Whole counties

Counties Bucks County, PA, Chester County, PA, Delaware County, PA, Montgomery County, PA, Philadelphia County, PA

The radar

The Philadelphia radar (KDIX), 82 km from the middle of the area, began a volume at 18:40 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, 6.7 hours before the alert went out and 217 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 1999-09-16Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 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 1999-09-16The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 131 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
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

Open this sounding in Storm Lab

The text

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

000 
TTAA00 KPHL 161839
FFWPHL
DEC003-NJC005-007-015-033-PAC017-029-045-091-101-170035-

BULLETIN - EAS ACTIVATION REQUESTED
SEVERE FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
241 PM EDT THU SEP 16 1999

THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ HAS ISSUED A

* SEVERE FLASH FLOOD WARNING FOR...
  CHESTER COUNTY IN PENNSYLVANIA.
  MONTGOMERY COUNTY IN PENNSYLVANIA.
  BUCKS COUNTY IN PENNSYLVANIA.
  DELAWARE COUNTY IN PENNSYLVANIA.
  PHILADELPHIA COUNTY IN PENNSYLVANIA.
  SALEM COUNTY IN NEW JERSEY.
  GLOUCESTER COUNTY IN NEW JERSEY.
  CAMDEN COUNTY IN NEW JERSEY.
  WESTERN BURLINGTON COUNTY IN NEW JERSEY.
  NEW CASTLE COUNTY IN DELAWARE.

* UNTIL 835 PM EDT.

* RAINFALL AMOUNTS OF 4 TO 8 INCHES HAVE FALLEN THROUGHOUT THE
AREA. MANY STREAMS AND CREEKS ARE OVERFLOWING THEIR BANKS AND
NUMEROUS ROADS ARE WATER COVERED AND IMPASSABLE. ANOTHER AREA
OF VERY HEAVY RAIN WILL OVERSPREAD THE PHILADELPHIA METROPOLITAN
AREA AS FLOYD MOVES UP THE EAST COAST. TRAVEL THROUGH THE
REMAINDER OF THE AFTERNOON AND EVENING HOURS SHOULD BE RESTRICTED
UNLESS ABSOLUTELY NECESSARY. THE RAIN WILL BEGIN TO TAPER OFF
FROM SOUTH TO NORTH LATER THIS EVENING.

  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
  RPW/WN

The office that day

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

IssuedProductOfficeCountiesLasted
Sep 16, 8:37 AM EDTFlash Flood WarningPHIChester, Delaware, Philadelphia4 hr
Sep 16, 9:25 AM EDTFlash Flood WarningPHIBucks, Montgomery6 hr
Sep 16, 11:25 AM EDTFlash Flood WarningPHIDelaware, Philadelphia6 hr
Sep 16, 11:25 AM EDTFlash Flood WarningPHIChester6 hr
Sep 16, 12:11 PM EDTFlash Flood WarningPHIBerks, Lehigh5 hr
Sep 16, 12:11 PM EDTFlash Flood WarningPHINorthampton5 hr
Sep 16, 3:21 PM EDTFlash Flood WarningPHICarbon, Monroe6 hr
Sep 16, 4:21 PM EDTFlash Flood WarningPHINorthampton5 hr
Sep 16, 4:21 PM EDTFlash Flood WarningPHIBerks, Lehigh5 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.