Alert archive / Pennsylvania / Severe Thunderstorm Warnings in 1989

Severe Thunderstorm Warning 4, NWS Philadelphia/Mount Holly

March 18, 1989Chester County, Pennsylvania

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Mar 18, 1989, 2:37 PM EST for Chester County, Pennsylvania. It was in force for 68 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
Mar 18, 1989, 2:37 PM EST (19:37 UTC)
Expired
Mar 18, 1989, 3:45 PM EST
In force
68 min
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.

What was reported inside it

TimeReportWhereRemark
Mar 18, 3:30 PM ESTThunderstorm Wind 78Chester, 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, 7.6 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 12:00Z on 1989-03-18Temperature 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 1989-03-18The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 7 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
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
1331 m above ground
0-6 km bulk shear
26 kt
0-1 km storm-relative helicity
7 m²/s²
0-3 km storm-relative helicity
2 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 181941
SVRPHL
PAC029-182045-
 
BULLETIN - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE PHILADELPHIA PA
237 PM EST SAT MAR 18 1989
 
THE NATIONAL WEATHER SERVICE IN PHILADELPHIA HAS ISSUED A
SEVERE THUNDERSTORM WARNING EFFECTIVE UNTIL  345 PM EST
FOR PEOPLE IN THE FOLLOWING COUNTY...
 
IN SOUTHEAST PENNSYLVANIA
          ...CHESTER
 
WEATHER SERVICE RADAR AT 240 INDICATED A SEVERE THUNDERSTORM IN
LANCASTER COUNTY WHICH WAS MOVING EAST AT 50 MILES AN HOUR. THIS STORM
SHOULD MOVE INTO THE WESTERN PORTIONS OF CHESTER COUNTY AROUND 300 PM
THIS AFTERNOON...AND MOVE EAST THROUGH THE REMAINDER OF THE COUNTY BY
400 THIS AFTERNOON.
 
 
 
THIS IS A DANGEROUS STORM.  IF YOU ARE IN THE WARNED AREA...BE
PREPARED FOR STRONG DAMAGING WINDS...LARGE HAIL...VERY HEAVY RAIN
AND DANGEROUS LIGHTNING.  SHOULD THE STORM APPROACH YOU...SEEK
IMMEDIATE SHELTER.  MOBILE HOMES ARE MOST VULNERABLE TO HIGH WINDS
AND SHOULD B=E AVOIDED.
 
WERT

Nearby

Severe Thunderstorm Warnings in Pennsylvania, 1989Every severe thunderstorm warning in 1989

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.