Alert archive / Pennsylvania / Flash Flood Warnings in 1987

Flash Flood Warning 5, NWS Philadelphia/Mount Holly

September 8, 1987Montgomery County, Pennsylvania

NWS Philadelphia/Mount Holly issued this flash flood warning at Sep 8, 1987, 11:11 PM EDT for Montgomery County, Pennsylvania. It was in force for 4 hr.

The area

The counties it named.

The facts

Issued
Sep 8, 1987, 11:11 PM EDT (03:11 UTC)
Expired
Sep 9, 1987, 3:00 AM EDT
In force
4 hr
Issued by
NWS Philadelphia/Mount Holly
Area
Whole counties

County 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 00:00Z, 3.2 hours before the alert went out and 112 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 1987-09-09Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 482 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 1987-09-09The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 80 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
482 J/kg
Mixed-layer CIN
-7 J/kg
Mixed-layer LCL
558 m above ground
0-6 km bulk shear
26 kt
0-1 km storm-relative helicity
80 m²/s²
0-3 km storm-relative helicity
108 m²/s²
Significant tornado parameter
0.1
Supercell composite
0.8

Open this sounding in Storm Lab

The text

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

000 
TTAA00 KPHL 090325 COR
FFWPHL
PAC091-090415-

BULLETIN - IMMEDIATE BROADCAST REQUESTED/EBS ACTIVATION REQUESTED
FLASH FLOOD WARNING...CORRECTION
NATIONAL WEATHER SERVICE PHILADELPHIA PA
1111 PM EDT TUE SEP 8 1987

THE NATIONAL WEATHER SERVICE HAS ISSUED A FLASH FLOOD WARNING
EFFECTIVE UNTIL 3 AM EDT FOR PEOPLE IN THE FOLLOWING COUNTY OF

SOUTHEAST PENNSYLVANIA...MONTGOMERY

FIVE INCHES OF RAIN WAS INDICATED BY AUTOMATIC RAIN GAGE IN
SECTIONS OF MONTGOMERY COUNTY. FLOODING IS  EXPECTED ALONG
THE PERIKIOMEN CREEK DURING THE NEXT FEW HOURS.

A FLASH FLOOD WARNING MEANS FLOODING IS IMMINENT

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.

 KWH

Nearby

Flash Flood Warnings in Pennsylvania, 1987Every flash flood warning in 1987

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.