Alert archive / Pennsylvania / Severe Thunderstorm Warnings in 1991

Severe Thunderstorm Warning 41, NWS Philadelphia/Mount Holly

August 3, 1991Philadelphia County, Pennsylvania

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Aug 3, 1991, 7:25 PM EDT for Philadelphia County, Pennsylvania. It was in force for 50 min. 1 report came from inside the area while it was in force.

The area

The counties it named, with what was reported inside it.

The facts

Issued
Aug 3, 1991, 7:25 PM EDT (23:25 UTC)
Expired
Aug 3, 1991, 8:15 PM EDT
In force
50 min
Issued by
NWS Philadelphia/Mount Holly
Area
Whole counties

County Philadelphia County, PA

What was reported inside it

TimeReportWhereRemark
Aug 3, 7:50 PM EDTThunderstorm Wind 57Philadelphia, PA

NCEI Storm Data entries that began inside the alert's area while it was in force. Before 2003 the local storm report archive is thin, so this is the record of what happened rather than what was phoned in. Storm Data before 1996 records only tornadoes, thunderstorm wind and hail.

The nearest sounding before it

Atlantic City In, NJ (KACY), launched 12:00Z, 11.4 hours before the alert went out and 82 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 1991-08-03Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 250 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 12:00Z on 1991-08-03The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 17 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
250 J/kg
Mixed-layer CIN
-186 J/kg
Mixed-layer LCL
1239 m above ground
0-6 km bulk shear
31 kt
0-1 km storm-relative helicity
17 m²/s²
0-3 km storm-relative helicity
76 m²/s²
Significant tornado parameter
-0.0
Supercell composite
-0.7

Open this sounding in Storm Lab

The text

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

000 
TTAA00 KPHL 032324 RRA
SVRPHL
PAC101-040015-
 
BULLETIN - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE PHILADELPHIA PA
725 PM EDT SAT AUG 3 1991
 
THE NATIONAL WEATHER SERVICE IN PHILADELPHIA HAS ISSUED A
SEVERE THUNDERSTORM WARNING EFFECTIVE UNTIL  815 PM EDT
FOR PEOPLE IN THE FOLLOWING LOCATION...
 
IN SOUTHEAST PENNSYLVANIA
 
   ...PHILADELPHIA COUNTY
 
AT 720 PM WEATHER SERVICE RADAR SHOWED THUNDERSTORMS IN
EASTERN CHESTER COUNTY OF PENNSYLVANIA THAT WERE MOVING EAST
TOWARD PHILADLPHIA COUNTY.  THESE THUNDERSTORMS PRODUCED HAIL
1/2 TO 1 INCH IN DIAMETER.  HAIL UP TO 1 INCH IN DIAMETER AND
GUSTY WINDS MAY ACCOMPANY THESE THUNDERSTORMS AS THEY MOVE
THROUGH PHILADELPHIA COUNTY.
 
 
THESE ARE DANGEROUS STORMS.  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 WINDOJWS.  MOBILE HOMES ARE MOST
VULNERABLE TO HIGH WINDS AND SHOULD BE AVOIDED.

The office that day

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

IssuedProductOfficeCountiesLasted
Aug 3, 7:04 PM EDTSevere Thunderstorm WarningPHIChester, Delaware26 min

Nearby

Severe Thunderstorm Warnings in Pennsylvania, 1991Every severe thunderstorm warning in 1991

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; verification from NCEI's Storm Data; the sounding from the Mesonet's radiosonde archive.