Alert archive / Pennsylvania / Flash Flood Warnings in 1990

Flash Flood Warning 5, NWS Philadelphia/Mount Holly

June 18, 1990Chester County, Delaware County, Montgomery County, Pennsylvania

NWS Philadelphia/Mount Holly issued this flash flood warning at Jun 18, 1990, 7:44 PM EDT for Chester County, Delaware County, Montgomery County, Pennsylvania. It was in force for 2 hr.

The area

The counties it named.

The facts

Issued
Jun 18, 1990, 7:44 PM EDT (23:44 UTC)
Expired
Jun 18, 1990, 9:45 PM EDT
In force
2 hr
Issued by
NWS Philadelphia/Mount Holly
Area
Whole counties

Counties Chester County, PA, Delaware 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, 11.7 hours before the alert went out and 108 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 1990-06-18Temperature 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, Atlantic City In, NJ at 12:00Z on 1990-06-18The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 12 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
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
1644 m above ground
0-6 km bulk shear
19 kt
0-1 km storm-relative helicity
12 m²/s²
0-3 km storm-relative helicity
53 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 182347
FFWPHL
PAC017-029-045-091-101-190145-
 
BULLETIN - EBS ACTIVATION REQUESTED
SMALL STREAM AND URBAN FLOOD WARNING
NATIONAL WEATHER SERVICE PHILADELPHIA PA
744 PM EDT MON JUN 18 1990
 
THE NATIONAL WEATHER SERVICE IN PHILADELPHIA HAS ISSUED A
SMALL STREAM AND URBAN FLOOD WARNING EFFECTIVE UNTIL  945 PM EDT
FOR PEOPLE IN THE FOLLOWING LOCATIONS...
 
IN SOUTHEAST PENNSYLVANIA
 
   ...SOUTHERN BUCKS COUNTY...CHESTER COUNTY...DELAWARE COUNTY
   ...MONTGOMERY COUNTY...PHILADELPHIA COUNTY
 
 
SEVERAL WEATHER SPOTTERS HAVE REPORTED HEAVY RAIN AND STREET FLOODING
IN MONTGOMERY COUNTY PENNSYLVANIA.  WEATHER SERVICE RADAR INDICATES
THUNDERSTORMS WITH HEAVY RAIN WILL BE MOVING THROUGH THE REST OF THE
PHILADELPHIA METROPOLITAN AREA BEFORE 9 PM.   HEAVY RAIN COULD CAUSE
SOME FLOODING OF SMALL STREAMS AND IN AREAS OF POOR DRAINAGE.
 
 
 
 
 
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.

The office that day

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

IssuedProductOfficeCountiesLasted
Jun 18, 7:44 PM EDTFlash Flood WarningPHIBucks, Philadelphia2 hr

Nearby

Flash Flood Warnings in Pennsylvania, 1990Every flash flood warning in 1990

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.