Alert archive / Pennsylvania / Flash Flood Warnings in 1989

Flash Flood Warning 17, NWS Philadelphia/Mount Holly

June 22, 1989Chester County, Montgomery County, Pennsylvania

NWS Philadelphia/Mount Holly issued this flash flood warning at Jun 22, 1989, 4:30 PM EDT for Chester County, Montgomery County, Pennsylvania. It was in force for 2 hr.

The area

The counties it named.

The facts

Issued
Jun 22, 1989, 4:30 PM EDT (20:30 UTC)
Expired
Jun 22, 1989, 6:30 PM EDT
In force
2 hr
Issued by
NWS Philadelphia/Mount Holly
Area
Whole counties

Counties Chester County, PA, Montgomery County, PA

The radar

The WSR-88D network and its archive begin in 1991, so there is no radar volume for this alert.

The nearest sounding before it

Atlantic City In, NJ (KACY), launched 12:00Z, 8.5 hours before the alert went out and 115 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, Atlantic City In, NJ at 12:00Z on 1989-06-22Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1253 joules per kilogram.LCLLFCEL10008507005003002001001 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, Atlantic City In, NJ at 12:00Z on 1989-06-22The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 7 square meters per square second.1939Sfc1 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
1253 J/kg
Mixed-layer CIN
-4 J/kg
Mixed-layer LCL
599 m above ground
0-6 km bulk shear
7 kt
0-1 km storm-relative helicity
7 m²/s²
0-3 km storm-relative helicity
0 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 222030
FFWPHL
PAC029-091-222230-

BULLETIN - IMMEDIATE BROADCAST REQUESTED/EBS ACTIVATION REQUESTED 
URBAN AND SMALL STREAM FLOOD WARNING 
NATIONAL WEATHER SERVICE PHILADELPHIA PA
430 PM EDT THU JUN 22 1989

THE NATIONAL WEATHER SERVICE HAS ISSUED A URBAN AND SMALL 
STREAM FLOOD WARNING EFFECTIVE UNTIL 630 PM EDT FOR PEOPLE IN 
THE FOLLOWING COUNTIES

   IN THE SOUTHEAST PART OF PENNSYLVANIA
      CHESTER...WESTERN MONTGOMERY

AT 430 PM EDT NATIONAL WEATHER SERVICE RADAR INDICATED THAT A
THUNDERSTORM WITH HEAVY RAIN WAS NEARLY STATIONARY ON THE BORDER
OF CHESTER AND LANCASTER COUNTIES.  ANOTHER THUNDERSTORM WITH
VERY HEAVY RAIN WAS ON THE BORDER OF CHESTER AND MONTGOMERY
COUNTIES.  THIS STORM IS MOVING SLOWLY NORTHWEST AND MAY MERGE
WITH THE ONE IN WESTERN CHESTER COUNTY.  FLOODING OF SMALL STREAMS
AND POOR DRAINAGE AREAS CAN BE EXPECTED IN THE WARNED AREA.

IF YOU ARE IN THE WARNED COUNTY IN AN AREA SUBJECT TO FLOODING
MOVE TO HIGHER GROUND. DO NOT DRIVE THROUGH FLOOD WATERS. CLIMBING
ATOP YOUR STALLED VEHICLE WILL NOT PREVENT YOU FROM BEING SWEPT
INTO DANGEROUS STREAM CONDITIONS AS WATER LEVELS RISE.

 DPG

The office that day

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

IssuedProductOfficeCountiesLasted
Jun 22, 2:09 PM EDTFlash Flood WarningPHIBucks, Montgomery, Philadelphia2 hr
Jun 22, 3:15 PM EDTFlash Flood WarningPHIDelaware3 hr
Jun 22, 3:50 PM EDTFlash Flood WarningPHIBucks, Delaware, Montgomery, Philadelphia115 min
Jun 22, 5:42 PM EDTFlash Flood WarningPHIBucks75 min

Nearby

Flash Flood Warnings in Pennsylvania, 1989Every flash flood warning in 1989

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.