Alert archive / Pennsylvania / Flash Flood Warnings in 1995

Flash Flood Warning 11, NWS Philadelphia/Mount Holly

July 21, 1995Delaware County, Montgomery County, Philadelphia County, Pennsylvania

NWS Philadelphia/Mount Holly issued this flash flood warning at Jul 21, 1995, 6:05 AM EDT for Delaware County, Montgomery County, Philadelphia County, Pennsylvania. It was in force for 55 min.

The area

The counties it named.

The facts

Issued
Jul 21, 1995, 6:05 AM EDT (10:05 UTC)
Expired
Jul 21, 1995, 7:00 AM EDT
In force
55 min
Issued by
NWS Philadelphia/Mount Holly
Area
Whole counties

Counties Delaware County, PA, Montgomery County, PA, Philadelphia County, PA

The radar

The Philadelphia radar (KDIX), 77 km from the middle of the area, began a volume at 10:04 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 00:00Z, 10.1 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 00:00Z on 1995-07-21Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 774 joules per kilogram.LCLEL10008507005003002001001 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 00:00Z on 1995-07-21The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 35 square meters per square second.19395878Sfc1 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
774 J/kg
Mixed-layer CIN
-4 J/kg
Mixed-layer LCL
1170 m above ground
0-6 km bulk shear
44 kt
0-1 km storm-relative helicity
35 m²/s²
0-3 km storm-relative helicity
67 m²/s²
Significant tornado parameter
0.1
Supercell composite
1.1

Open this sounding in Storm Lab

The text

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

000 
TTAA00 KPHL 211010
FFWPHL
PAC045-091-101-211100-
 
BULLETIN - EBS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE PHILADELPHIA/MOUNT HOLLY NJ
605 AM EDT FRI JUL 21 1995
 
THE NATIONAL WEATHER SERVICE IN PHILADELPHIA/MOUNT HOLLY HAS ISSUED A
FLASH FLOOD WARNING EFFECTIVE UNTIL  700 AM EDT
FOR PEOPLE IN THE FOLLOWING LOCATIONS...
 
IN  PENNSYLVANIA
 
   ...NORTHERN DELAWARE COUNTY...SOUTHERN MONTGOMERY COUNTY
   ...PHILADELPHIA COUNTY
 
AT 605 AM...NATIONAL WEATHER SERVICE RADAR INDICATED A THUNDERSTORM
MOVING EAST FROM CHESTER COUNTY INTO SOUTHERN MONTGOMERY...NORTHERN
DELAWARE AND PHILADELPHIA COUNTIES IN PENNSYLVANIA. RADAR SHOWED
POTENTIAL RAINFALL OF 2 INCHES WITHIN AN HOUR FROM THIS THUNDERSTORM.
 
URBAN ROADWAYS NEAR ROUTE 202 AND THE SCHUYLKILL EXPRESSWAY IN
PHILADELPHIA...MONTGOMERY AND DELAWARE COUNTIES WILL LIKELY BECOME FLOOD
. 
DO NOT ATTEMPT TO DRIVE THROUGH FLOODED AREAS.  THE DEPTH OF THE
WATER MAY BE HIGHER THAN YOU THINK.  RAPIDLY RISING WATERS CAN
QUICKLY ENGULF YOUR VEHICLE AND ITS OCCUPANTS...WASHING THEM AWAY.
REMEMBER...MOST FLASH FLOOD DEATHS OCCUR IN AUTOMOBILES.
 
 
RNS

The office that day

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

IssuedProductOfficeCountiesLasted
Jul 21, 5:00 AM EDTFlash Flood WarningPHIChester60 min
Jul 21, 5:00 AM EDTSevere Thunderstorm WarningPHIChester60 min

Nearby

Flash Flood Warnings in Pennsylvania, 1995Every flash flood warning in 1995

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.