Alert archive / Pennsylvania / Severe Thunderstorm Warnings in 1991

Severe Thunderstorm Warning 3, NWS Philadelphia/Mount Holly

May 6, 1991Chester County, Pennsylvania

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at May 6, 1991, 5:43 PM EDT for Chester County, Pennsylvania. It was in force for 32 min.

The area

The counties it named.

The facts

Issued
May 6, 1991, 5:43 PM EDT (21:43 UTC)
Expired
May 6, 1991, 6:15 PM EDT
In force
32 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 12:00Z, 9.7 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 1991-05-06Temperature 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 1991-05-06The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 224 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
574 m above ground
0-6 km bulk shear
28 kt
0-1 km storm-relative helicity
224 m²/s²
0-3 km storm-relative helicity
288 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 062145
SVRPHL
PAC029-062215-
 
BULLETIN - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE PHILADELPHIA PA
543 PM EDT MON MAY 6 1991
 
THE NATIONAL WEATHER SERVICE IN PHILADELPHIA HAS ISSUED A
SEVERE THUNDERSTORM WARNING EFFECTIVE UNTIL  615 PM EDT
FOR PEOPLE IN THE FOLLOWING LOCATION...
 
IN SOUTHEAST PENNSYLVANIA
 
   ...CHESTER COUNTY
 
AT 540 PM WEATHER SERVICE RADAR INDICATED A LINE OF
THUNDERSTORMS MOVING INTO WESTERN CHESTER COUNTY. THESE THUNDERSTORMS
PRODUCED WIND GUSTS TO OVER 60 MPH AS THEY MOVED THROUGH LANCASTER
COUNTY.  HAIL IS ALSO POSSIBLE WITH THESE THUNDERSTORMS AS THEY MOVE
THROUGH CHESTER COUNTY.
 
A TORNADO WATCH CONTINUES FOR SOUTHEASTERN
PENN6SYLVANIA AND SOUTHERN NEW JERSEY UNTIL 1000 PM EDT.  REMEMBER
SEVERE THUNDERSTORMS CAN AND OCCASIONALLY DO PRODUCE TORNADOES WITH
LITTLE OR NO ADVANCED WARNING.

What forecasters said that day

The local office's own words before this severe thunderstorm warning went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

In the hours before

Special weather statement, May 6, 4:10 PM EDT, 1 hour 33 minutes before
061955-002-004-062100

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE ATLANTIC CITY NJ
355 PM EDT MON MAY 06 1991

...TORNADO WATCH IN EFFECT FOR SOUTHERN NEW JERSEY UNTIL 10 PM EDT...

NO SEVERE WEATHER HAS BEEN DETECTED OVER SOUTHERN NEW JERSEY AT THIS TIME.

MOIST AND UNSTABLE AIR OVER THE AREA IN ADVANCE OF A COLD FRONT THIS
AFTERNOON. FRONT EXTENDED FROM LAKE ONTARIO INTO CENTRAL PENNSYLVANIA AND
EASTERN WEST VIRGINIA THEN CONTINUED SOUTH INTO THE SOUTHEAST STATES. THIS
FRON WILL CROSS SOUTHERN NEW JERSEY DURING THE EVENING.

SEVERE THUNDERSTORMS AS WELL AS POSSIBLE TORNADOES MAY BE ASSOCIATED WITH
THIS FRONT. THUNDERSTORMS MAY CONTAIN HEAVY DOWNPOURS...FREQUENT DANGEROUS
LIGHTNING...POSSIBLE HAIL AND STRONG GUSTY WINDS. RESIDENTS SHOULD BE
PREPARED TO SEEK SHELTER IF THREATNING APPROACHES. LIGHTNING AND ACCIDENTS
ASSOCIATED WITH LIGHTNING KILL MORE PEOPLE EACH YEAR THAN ANY OTHER WEATHER
EVENT.

REMEMBER...A TORNADO WATCH MEANS CONDITIONS ARE FAVORABLE FOR TORNADOES
AND SEVERE THUNDERSTORMS TO DEVELOP IN AND CLOSE TO A WATCH AREA. PERSONS
SOUTHERN NEW JERSEY SHOULD BE ON THE LOOKOUT FOR THREATNING WEATHER
CONDITIONS AND LISTEN FOR LATER STATEMENTS AND POSSIBLE WARNINGS.
BE PREPARED TO SEEK SHELTER IF SEVERE WEATHER APPROACHES.

BUDMAN/BUBBA
Special weather statement, May 6, 4:44 PM EDT, 59 minutes before
061955-002-004-062200

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE ATLANTIC CITY NJ
435 PM EDT MON MAY 06 1991

...TORNADO WATCH IN EFFECT FOR SOUTHERN NEW JERSEY UNTIL 10 PM EDT...

NO SEVERE WEATHER HAS BEEN DETECTED OVER SOUTHERN NEW JERSEY AT THIS TIME.

SEVERE THUNDERSTORMS HAVE BEEN REPORTED IN WESTERN PENNSYLVANIA WITH WIND
GUSTS TO 62 MAH AND HAIL STONES TO 1/4 INCH.

AT 430 PM...OUR WEATRHER SEARCH RADAR INDICATED SCATTERED SHOWERS FROM
MANASQUAN COASTAL CENTRAL NEW JERSEY ACROSS TO SALEM IN SOUTHWEST NEQ JERSEY.
ALSO SHOWERE WERE SCATTERED OVER EASTERN AND SOUTHEAST PENNSYLAVNIA.

SHOWERS AND THUNDERSTORMS WERE DETECTED IN A BAND ABOUT 30 MILES WIDE FROM
CENTRAL PENNSYLVANIA INTO NORTHWEST MARYLAND. HEAVIEST STORM WERE INDICATED
IN PENNSYLVANIA JUST TO THE WEST OF GETTSBURG AND HARRISBURG. MOVEMENT WAS
TO THE NORTHEAST AT 35 MILES AN HOUR.

REMEMBER...A TORNADO WATCH MEANS CONDITIONS ARE FAVORABLE FOR TORNADOES
AND SEVERE THUNDERSTORMS TO DEVELOP IN AND CLOSE TO A WATCH AREA. PERSONS
SOUTHERN NEW JERSEY SHOULD BE ON THE LOOKOUT FOR THREATNING WEATHER
CONDITIONS AND LISTEN FOR LATER STATEMENTS AND POSSIBLE WARNINGS.
BE PREPARED TO SEEK SHELTER IF SEVERE WEATHER APPROACHES.

FXD/WS/PM
Special weather statement, May 6, 4:58 PM EDT, 45 minutes before
PAZ011-016-062200-

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE ALLENTOWN PA
445 PM EDT MON MAY 6 1991

...TORNADO WATCH IN EFFECT UNTIL 10 PM EDT FOR BERKS COUNTY...
...SEVERE THUNDERSTORM WATCH UNTIL 10 PM EDT FOR EAST CENTRAL
   PENNSYLVANIA...

THE NATIONAL WEATHER SERVICE HAS ISSUED A TORNADO WATCH FOR BERKS
COUNTY UNTIL 10 PM AND A SEVERE THUNDERSTORM WATCH FOR BERKS...
LEHIGH...NORTHAMPTON...SCHUYLKILL...CARBON...MONROE AND PIKE COUNTIES.

THE THREAT OF SEVERE THUNDERSTORMS WITH DAMAGING WINDS...LARGE HAIL
AND DANGEROUS LIGHTNING EXIT IN AND CLOSE TO THE WATCH AREA UNTIL 10
PM EDT.

AT 445 PM EDT...NATIONAL WEATHER SERVICE RADAR INDICATED A LINE OF
HEAVY THUNDERSTORMS EXTENDING FROM WILLIAMSPORT SOUTH TO HARRISBURG.
THE LINE IS MOVING EAST AT ABOUT 40 MPH AND WILL MOVE THROUGH
EASTERN PENNSYLVANIA BETWEEN 6 AND 10 PM.

REMEMBER...A TORNADO AND SEVERE THUNDERSTORM WATCH MEAN CONDITIONS
ARE FAVORABLE FOR THE DEVELOPMENT OF TORNADOES AND SEVERE
THUNDERSTORMS. PEOPLE LIVING IN EAST CENTRAL AND SOUTHEAST
PENNSYLVANIA SHOULD BE ALERT FOR THREATENING WEATHER.

STAY TUNED TO NOAA WEATHER RADIO OR YOUR LOCAL RADIO AND TELEVISION
STATIONS FOR THE LATEST INFORMATION ON THIS WEATHER SITUATION.

DOVICO
Special weather statement, May 6, 5:23 PM EDT, 20 minutes before
PAZ007>012-016-NJZ002>004-006-062300-

SEVERE WEATHER STATEMENT -
NATIONAL WEATHER SERVICE PHILADELPHIA PA
530 PM EDT MON MAY 6 1991

...TORNADO WATCH IN EFFECT FOR SOUTHEAST PENNSYLVANIA AND MOST
OF SOUTHERN NEW JERSEY TIL 10 PM EDT...

AT 5 15 PM AN AREA OF SHOWERS AND STRONG THUNDERSTORMS EXTENDED
FROM WESTERN NEW YORK STATE TO SOUTHWEST NORTH CAROLINA.  IN
PENNSYLVANIA THE LEADING EDGE OF THE STORMS EXTENDED FROM BRADFORD
COUNTY IN THE NORTH TO LANCASTER COUNTY IN THE SOUTH.

THE STORMS ARE MOVING EAST NORTHEAST AT 45 MILES AN HOUR.  SOME
INDIVIDUAL STORMS ARE MOVING AS FAST AS 55 MILES AN HOUR.

FOR THE NEXT COUPLE OF HOURS THESE STORMS WILL BE MOVING VERY
QUICKLY ACROSS CENTRAL AND EASTERN PENNSYLVANIA AND INTO NEW
JERSEY.

TORNADOES...STRONG WIND GUSTS...HAIL...AND DANGEROUS LIGHTNING
CAN BE EXPECTED WITH THESE STORMS.

STAY TUNED TO NOAA WEATHER RADIO OR YOUR LOCAL RADIO AND TELEVISION
STATIONS THIS AFTERNOON AND EVENING FOR ANY ADDITIONAL SEVERE WEATHER
WATCHES...WARNINGS OR STATEMENTS.

JEJ
Special weather statement, May 6, 5:25 PM EDT, 18 minutes before
PAZ007>012-016-NJZ002>004-006-062300-

SEVERE WEATHER STATEMENT -
NATIONAL WEATHER SERVICE PHILADELPHIA PA
530 PM EDT MON MAY 6 1991

...TORNADO WATCH IN EFFECT FOR SOUTHEAST PENNSYLVANIA AND MOST
OF SOUTHERN NEW JERSEY TIL 10 PM EDT...

AT 5 15 PM AN AREA OF SHOWERS AND STRONG THUNDERSTORMS EXTENDED
FROM WESTERN NEW YORK STATE TO SOUTHWEST NORTH CAROLINA.  IN
PENNSYLVANIA THE LEADING EDGE OF THE STORMS EXTENDED FROM BRADFORD
COUNTY IN THE NORTH TO LANCASTER COUNTY IN THE SOUTH.

THE STORMS ARE MOVING EAST NORTHEAST AT 45 MILES AN HOUR.  SOME
INDIVIDUAL STORMS ARE MOVING AS FAST AS 55 MILES AN HOUR.

FOR THE NEXT COUPLE OF HOURS THESE STORMS WILL BE MOVING VERY
QUICKLY ACROSS CENTRAL AND EASTERN PENNSYLVANIA...INCLUDING
THE PHILADELPHIA METROPOLITAN AREA...AND INTO SOUTHERN NEW JERSEY.

TORNADOES...STRONG WIND GUSTS...HAIL...AND DANGEROUS LIGHTNING
CAN BE EXPECTED WITH THESE STORMS.

STAY TUNED TO NOAA WEATHER RADIO OR YOUR LOC AL RADIO AND TELEVISION
STATIONS THIS AFTERNOON AND EVENING FOR ANY ADDITIONAL SEVERE WEATHER
WATCHES...WARNINGS OR STATEMENTS.

JEJ
Special weather statement, May 6, 5:28 PM EDT, 15 minutes before
DEZALL-062300-

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE WILMINGTON DE
528 PM EDT MON MAY 6 1991

...THUNDERSTORMS HEADING FOR THE FIRST STATE...
...TORNADO WATCH IN EFFECT UNTIL 10 PM EDT TONIGHT...

 AT 515 PM WEATHER RADAR SHOWED A LINE OF THUNDERSTORMS EXTENDING FROM
40 MILES NORTHWEST OF THE NEW CASTLE COUNTY AIRPORT TO 15 MILES WEST OF
BALTIMORE TO JUST WEST OF WASHINGTON AND SOUTHWARD INTO VIRGINIA. THESE
ARE MOVING EAST AT 30 MPH AND WILL BE REACHING NORTHERN DELAWARE AROUND
630 PM...AND A LITTLE LATER FROM 7PM TO 8PM DOWNSTATE.
 THESE THUNDERSTORMS HAVE BEEN PRODUCING SOME STRONG GUSTY WINDS AND
RADAR INDICATES THE POSSIBILITY OF HAIL IN SOME OF THESE THUNDERSTORMS.
 IN THE HARRISBURG AREA...WINDS GUSTED TO 52 MPH SHORTLY BEFORE 5PM
IN A HEAVY SHOWER...AND AT DULLES AIRPORT WINDS GUSTED TO 40 MPH.
NO TORNADOES HAVE BEEN SIGHTED AS YET...BUT A TORNADO WATCH IS IN EFFECT FOR
ALL OF DELAWARE UNTIL 10PM. SEVERE THUNDERSTORMS CAN PRODUCE TORNADOES
WITH LITTLE WARNING. PERSONS IN THE WATCH AREA SHOULD BE ALERT AND PREPARED
TO TAKE PROTECTIVE MEASURES IMMEDIATELY WHEN THE THUNDERSTORMS REACH
THE STATE.
LISTEN FOR LATER STATEMENTS OR WARNINGS ON NOAA WEATHER RADIO OR
LOCAL TV AND RADIO STATIONS.
CS

The office that day

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

IssuedProductOfficeCountiesLasted
May 6, 6:06 PM EDTSevere Thunderstorm WarningPHIMontgomery54 min
May 6, 6:48 PM EDTSevere Thunderstorm WarningPHIPhiladelphia27 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; the sounding from the Mesonet's radiosonde archive.