Alert archive / Pennsylvania / Flash Flood Warnings in 1988

Flash Flood Warning 1, NWS Philadelphia/Mount Holly

May 19, 1988Chester County, Pennsylvania

NWS Philadelphia/Mount Holly issued this flash flood warning at May 19, 1988, 5:55 AM EDT for Chester County, Pennsylvania. It was in force for 2 hr.

The area

The counties it named.

The facts

Issued
May 19, 1988, 5:55 AM EDT (09:55 UTC)
Expired
May 19, 1988, 7:55 AM EDT
In force
2 hr
Issued by
NWS Philadelphia/Mount Holly
Area
Whole counties

County Chester 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, 9.9 hours before the alert went out and 122 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 1988-05-19Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 km2 km3 km6 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 1988-05-19The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 107 square meters per square second.193958Sfc1 km3 km6 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
714 m above ground
0-6 km bulk shear
29 kt
0-1 km storm-relative helicity
107 m²/s²
0-3 km storm-relative helicity
77 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 191013 COR
FFWPHL
PAC029-191300-

BULLETIN - EBS ACTIVATION REQUESTED
SMALL STREAM AND URBAN FLOOD WARNING...CORRECTED
NATIONAL WEATHER SERVICE PHILADELPHIA PA
555 AM EDT THU MAY 19 1988

THE NATIONAL WEATHER SERVICE IN PHILADELPHIA HAS ISSUED A
SMALL STREAM AND URBAN FLOOD WARNING EFFECTIVE UNTIL  900 AM EDT
FOR PEOPLE IN THE FOLLOWING COUNTY...

IN SOUTHEAST PENNSYLVANIA
          ...CENTRAL CHESTER

AT 530 AM...AUTOMATIC RIVER GAGE SHOWED THE BRANDYWINE CREEK AT
7.60 FEET AT DOWNINGTOWN.  FLOOD STAGE AT DOWNINGTOWN IS 7.00 FEET.
THE RAINS WILL CONTINUE THIS MORNING...BEFORE SHIFTING SLOWLY
TO THE WEST OF THE 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.

JWH

...CORRECTED TO REFERENCE DOWNINGTOWN PA

Nearby

Flash Flood Warnings in Pennsylvania, 1988Every flash flood warning in 1988

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.