Alert archive / Pennsylvania / Flash Flood Warnings in 1994

Flash Flood Warning 9, NWS Philadelphia/Mount Holly

July 27, 1994Chester County, Pennsylvania

NWS Philadelphia/Mount Holly issued this flash flood warning at Jul 27, 1994, 10:28 PM EDT for Chester County, Pennsylvania. It was in force for 62 min.

The area

The counties it named.

The facts

Issued: Jul 27, 1994, 10:28 PM EDT (02:28 UTC)
Expired: Jul 27, 1994, 11:30 PM EDT
In force: 62 min
Issued by: NWS Philadelphia/Mount Holly
Area: Whole counties

County Chester County, PA

The nearest sounding before it

Atlantic City In, NJ (KACY), launched 00:00Z, 2.5 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-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

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: 181 J/kg
Mixed-layer CIN: -23 J/kg
Mixed-layer LCL: 726 m above ground
0-6 km bulk shear: 35 kt
0-1 km storm-relative helicity: 82 m²/s²
0-3 km storm-relative helicity: 123 m²/s²
Significant tornado parameter: 0.1
Supercell composite: 1.3

Open this sounding in Storm Lab

The text

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

000 
TTAA00 KPHL 280228
FFWPHL
PAC029-280330-
 
BULLETIN - EBS ACTIVATION REQUESTED
SEVERE THUNDERSTORM AND FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE PHILADELPHIA/MOUNT HOLLY NJ
1028 PM EDT WED JUL 27 1994
 
THE NATIONAL WEATHER SERVICE IN PHILADELPHIA/MOUNT HOLLY HAS ISSUED A
SEVERE THUNDERSTORM AND FLASH FLOOD WARNING
EFFECTIVE UNTIL 1130 PM EDT FOR PEOPLE IN THE FOLLOWING LOCATION...
 
IN SOUTHEAST PENNSYLVANIA
 
   ...CHESTER COUNTY
 
AT 1025 PM...NATIONAL WEATHER SERVICE RADAR SHOWED A SEVERE THUNDERSTORM
IN NORTHERN CECIL COUNTY MARYLAND...WHICH WAS MOVING NORTHEAST AT 20 TO
30 MPH INTO SOUTHERN CHESTER COUNTY. THIS STORM HAS A HISTORY OF
PRODUCING DAMAGING WIND GUSTS AND FLOODING RAINS.
 
THIS IS A DANGEROUS STORM.  IF YOU ARE IN THE WARNED AREA...PREPARE
FOR STRONG DAMAGING WINDS...LARGE HAIL...VERY HEAVY RAIN AND DEADLY
LIGHTNING.  SHOULD THE STORM APPROACH YOU...SEEK IMMEDIATE SHELTER
INDOORS...BUT DO NOT STAND NEAR WINDOWS.  MOBILE HOMES ARE MOST
VULNERABLE TO HIGH WINDS AND SHOULD BE AVOIDED.
 
A TORNADO/SEVERE THUNDERSTORM WATCH CONTINUES FOR SOUTHEASTERN
PENNSYLVANIA AND SOUTHERN NEW JERSEY UNTIL 1100 PM EDT.  REMEMBER
SEVERE THUNDERSTORMS CAN AND OCCASIONALLY DO PRODUCE TORNADOES WITH
LITTLE OR NO ADVANCED WARNING.
 
HEAVY RAINS WITH THIS THUNDERSTORM MAY CAUSE FLOODING OF SMALL
STREAMS AND UNDERPASSES VERY QUICKLY.  DO NOT DRIVE YOUR CAR INTO
AREAS WHERE THE WATER COVERS THE ROADWAY.  THE WATER MAY BE DEEPER
THAN YOU THINK.  IF CAUGHT IN RISING WATERS...ABANDON YOUR CAR
QUICKLY.  MOVE TO HIGHER GROUND.
 
KRAUS

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 27, 10:28 PM EDT	Severe Thunderstorm Warning	PHI	Chester	62 min
Jul 27, 11:08 PM EDT	Tornado Warning	PHI	Chester	52 min
Jul 27, 11:31 PM EDT	Severe Thunderstorm Warning	PHI	Montgomery	44 min
Jul 28, 12:00 AM EDT	Tornado Warning	PHI	Montgomery	45 min

Nearby

Flash Flood Warnings in Pennsylvania, 1994 Every flash flood warning in 1994

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.