Alert archive / Pennsylvania / Flash Flood Warnings in 1989

Flash Flood Warning 9, NWS Philadelphia/Mount Holly

June 9, 1989Delaware County, Pennsylvania

NWS Philadelphia/Mount Holly issued this flash flood warning at Jun 9, 1989, 11:09 PM EDT for Delaware County, Pennsylvania. It was in force for 3 hr.

The area

The counties it named.

The facts

Issued
Jun 9, 1989, 11:09 PM EDT (03:09 UTC)
Expired
Jun 10, 1989, 2:15 AM EDT
In force
3 hr
Issued by
NWS Philadelphia/Mount Holly
Area
Whole counties

County Delaware 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 00:00Z, 3.2 hours before the alert went out and 93 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 00:00Z on 1989-06-10Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 562 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 00:00Z on 1989-06-10The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 88 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
562 J/kg
Mixed-layer CIN
-23 J/kg
Mixed-layer LCL
594 m above ground
0-6 km bulk shear
38 kt
0-1 km storm-relative helicity
88 m²/s²
0-3 km storm-relative helicity
122 m²/s²
Significant tornado parameter
0.2
Supercell composite
1.6

Open this sounding in Storm Lab

The text

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

000 
TTAA00 KPHL 100312
FFWPHL
PAC045-100615-
 
BULLETIN - EBS ACTIVATION REQUESTED
SMALL STREAM AND URBAN FLOOD WARNING
NATIONAL WEATHER SERVICE PHILADELPHIA PA
1109 PM EDT FRI JUN 9 1989
 
THE NATIONAL WEATHER SERVICE IN PHILADELPHIA HAS ISSUED A
SMALL STREAM AND URBAN FLOOD WARNING EFFECTIVE UNTIL 215 AM EDT
FOR PEOPLE IN THE FOLLOWING COUNTY...
 
IN SOUTHEAST PENNSYLVANIA
          ...DELAWARE
 
RAINFALL TOTALS OF BETWEEN 1 AND 2 INCHES DURING THE PAST SEVERAL
HOURS HAVE CAUSED MANY SMALL STREAMS AND CREEKS IN DELAWARE COUNTY TO
RISE RAPIDLY...WITH SOME STREAMS NOW ABOVE BANKFULL. THE AUTOMATIC
STREAM GAGE ON THE CHESTER CREEK AT CHESTER REPORTED A LEVEL OF 9.93
FEET. THE FLOOD STAGE OF THE CHESTER CREEK AT CHESTER IS 9.00 FEET.
 
PRECIPITATION FREQUENCY AND DURATION IS EXPECTED TO CONTINUE TO
DECREASE DURING THE NEXT SEVERAL HOURS OVER DELAWARE COUNTY...AND
STREAM AND CREEK LEVELS SHOULD BEGIN TO SUBSIDE SHORTLY AFTER
MIDNIGHT.  THE LEVEL OF THE CHESTER CREEK IS EXPECTED TO FALL BACK
BELOW FLOOD STAGE BY 215 AM EARLY SATURDAY MORNING.
 
 
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 VEoHICLE WILL NOT PREVENT YOU FROM
BEING SWEPT INTO DANGEROUS STREAM CONDITIONS AS WATER LEVELS RISE.
 
WERT

The office that day

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

IssuedProductOfficeCountiesLasted
Jun 9, 8:17 PM EDTSevere Thunderstorm WarningPHIPhiladelphia58 min
Jun 9, 8:17 PM EDTSevere Thunderstorm WarningPHIDelaware58 min
Jun 9, 11:36 PM EDTFlash Flood WarningPHIBucks3 hr

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.