Alert archive / Pennsylvania / Severe Thunderstorm Warnings in 1991

Severe Thunderstorm Warning 6, NWS Philadelphia/Mount Holly

May 6, 1991Philadelphia County, Pennsylvania

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at May 6, 1991, 6:48 PM EDT for Philadelphia County, Pennsylvania. It was in force for 27 min.

The area

The counties it named.

The facts

Issued
May 6, 1991, 6:48 PM EDT (22:48 UTC)
Expired
May 6, 1991, 7:15 PM EDT
In force
27 min
Issued by
NWS Philadelphia/Mount Holly
Area
Whole counties

County Philadelphia County, PA

The nearest sounding before it

Atlantic City In, NJ (KACY), launched 12:00Z, 10.8 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 1991-05-06Temperature 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 062250
SVRPHL
PAC101-062315-
 
BULLETIN - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE PHILADELPHIA PA
648 PM EDT MON MAY 6 1991
 
THE NATIONAL WEATHER SERVICE IN PHILADELPHIA HAS ISSUED A
SEVERE THUNDERSTORM WARNING EFFECTIVE UNTIL  715 PM EDT
FOR PEOPLE IN THE FOLLOWING LOCATION...
 
IN SOUTHEAST PENNSYLVANIA
 
   ...PHILADELPHIA COUNTY
 
AT 645 PM WEATHER SERVICE RADAR SHOWED THUNDERSTORMS MOVING
THROUGH PHILADELPHIA COUNTY. SOME OF THESE THUNDERSTORMS MAY
BE ACCOMPANIED BY WIND GUSTS TO OVER 60 MPH.
 
WIND GUSTS OF 54 MPH WERE REPORTED WHEN THE THUNDERSTORMS PASSED
OVER INTERNATIONAL AIRPORT.
 
 
 
A TORNADO WATCH CONTINUES FOR SOUTHEASTERN
PENNSYLVANIA 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, 5:23 PM EDT, 1 hour 25 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, 1 hour 23 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, 1 hour 20 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
Special weather statement, May 6, 5:51 PM EDT, 57 minutes before
062145-002-004-062300

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE ATLANTIC CITY NJ
545 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.

AT 430 PM...OUR WEATRHER SEARCH RADAR INDICATED SCATTERED SHOWERS OVER
NORTHWEST AND NORTH CENTRAL NEW JERSEY. MOVEMENT WAS MOVING NORTHEAST AT
35 MILES AN HOUR.

THUNDERSTORMS...SOME WITH VERY HEAVY RAIN AND HAIL...WERE INDICATED IN THE
LOWER SUSQUEHANNA VALLEY OF PENNSYLVANIA MOVING INTO CHESTER COUNTY SOUTHEAST
PENNSYLVANIA. STORNG GUSTY WINDS AND FREQUENT LIGHTNING ARE ALSO ASSOCIATED
WITH THESE STORM AS THEY MOVE EASTNORTHEAST AT 50 MILES AN HOUR.

OTHER SHOWERS AND THUNDERSTORMS EXTENDED FROM BETWEEN WILLIAMSPORT AND
ALLENTOWN PENNSYLVANIA DWON THROUGH THE SUSQUEHANNA VALLEY OF PENNSYLVANIA

...SOUTHEAST PENNSYLVANIA AND NORTHERN INTO CENTRAL MARYLAND. THIS AREA
WAS MOVING EAST AT 30 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
IN SOUTHERN NEW JERSEY SHOULD BE ON THE LOOKOUT FOR THREATNING WEJATHER
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, 6:46 PM EDT, 2 minutes before
NJZ003-004-062355-

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

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

AT 630 PM...RADAR INDICATED A POSSIBLE SEVERE THUNDERSTORM PASSING SALEM
SOUTHWEST NEW JERSEY INTO GLOUCESTER COUNTY NEAR WILLIAMSTOWN. HAIL WAS
REPORTED WITH THIS STORM OF 3/8 INCH AS IT PASSED WILMINGTON DELAWARE.
OTHER THUNDERSTORMS WITH VERY HEAVY RAIN...POSSIBLE HAIL...STRONG GUSTY
WINDS TO 60 MPH AND FREQUENT DANGEROUS LIGHTNING EXTENDED ALONG THE NEW
JERSEY/PENNSYLVANIA BORDER FROM EASTON TO JUST NORTH OF TRENTON. MOVEMENT
WAS EAST TO EASTNORTHEAST AT 55 MILES AN HOUR. ANOTHER STORM WAS INDICATED
ON THE EASTERN SHORE OF THE CHESAPEAKE BAY MARYLANDBETWEEN CHESTERTOWN AND
CENTERVILLE.

OTHER SHOWERS AND THUNDERSTORMS EXTENDED FROM NORTHEAST PENNSYLVANIA INTO
EASTERN AND SOUTHEAST PENNSYLVANIA...PUSHING INTO EXTREME WESTERN NEW JERSEY
...NORTHERN AND CENTRAL DELAWARE INTO MARYLAND. THIS AREA WAS MOVING EAST

AT 35 MILES AN HOUR...WHILE THE STORM MOVED EASTNORTHEAST AT 50 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
IN 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
Special weather statement, May 6, 6:48 PM EDT, 0 minutes before
DEZ003-002-001-070045-

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

...THUNDERSTORMS MOVING THROUGH NORTHERN DELAWARE...AND HEADING FOR
CENTRAL AND SOUTH

The office that day

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

IssuedProductOfficeCountiesLasted
May 6, 5:43 PM EDTSevere Thunderstorm WarningPHIChester32 min
May 6, 6:06 PM EDTSevere Thunderstorm WarningPHIMontgomery54 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.