Alert archive / Pennsylvania / Severe Thunderstorm Warnings in 1991
Severe Thunderstorm Warning 34, NWS Philadelphia/Mount Holly
NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Jul 13, 1991, 7:47 PM EDT for Philadelphia County, Pennsylvania. It was in force for 58 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
- Jul 13, 1991, 7:47 PM EDT (23:47 UTC)
- Expired
- Jul 13, 1991, 8:45 PM EDT
- In force
- 58 min
- Issued by
- NWS Philadelphia/Mount Holly
- Area
- Whole counties
County Philadelphia County, PA
What was reported inside it
| Time | Report | Where | Remark |
|---|---|---|---|
| Jul 13, 8:05 PM EDT | Hail 0.75 | Philadelphia, 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, 11.8 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.
- Mixed-layer CAPE
- 257 J/kg
- Mixed-layer CIN
- -4 J/kg
- Mixed-layer LCL
- 629 m above ground
- 0-6 km bulk shear
- 32 kt
- 0-1 km storm-relative helicity
- 82 m²/s²
- 0-3 km storm-relative helicity
- 205 m²/s²
- Significant tornado parameter
- 0.1
- Supercell composite
- 0.9
The text
As transmitted, in the capitals the NWS used until 2016.
000 TTAA00 KPHL 132349 SVRPHL PAC101-140045- BULLETIN - IMMEDIATE BROADCAST REQUESTED SEVERE THUNDERSTORM WARNING NATIONAL WEATHER SERVICE PHILADELPHIA PA 747 PM EDT SAT JUL 13 1991 THE NATIONAL WEATHER SERVICE IN PHILADELPHIA HAS ISSUED A SEVERE THUNDERSTORM WARNING EFFECTIVE UNTIL 845 PM EDT FOR PEOPLE IN THE FOLLOWING LOCATION... IN SOUTHEAST PENNSYLVANIA ...PHILADELPHIA COUNTY AT 740 PM WEATHER SERVICE RADAR SHOWED AN AREA OF THUNDERSTORMS MOVING INTO PHILADELPHIA COUNTY FROM THE WEST. THESE THUNDERSTORMS PRODUCED WIND GUSTS TO 50 MPH AS THEY MOVED THROUGH WAYNE DELAWARE COUNTY EARLIER. THESE THUNDERSTORMS MAY HAVE STRONG DAMAGING WINDS... VERY HEAVY RAIN...AND HAIL. THESE THUNDERSTORMS WERE MOVING EAST AROUND 30 MPH. THESE ARE DANGEROUS STORMS. IF YOU ARE IN THE WARN ED 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 SEVERE THUNDERSTORM 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, Jul 13, 6:17 PM EDT, 1 hour 30 minutes before
DEZ003-140015- SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE WILMINGTON DE 610 PM EDT SAT JUL 13 1991 ...SEVERE THUNDERSTORM WATCH FOR MOST OF EASTERN PENNSYLVANIA...ALL OF SOUTHERN NEW JERSEY...AND NORTHERN DELAWARE UNTIL 10 PM EDT... A SEVERE THUNDERSTORM WATCH HAS BEEN PLACED IN EFFECT FOR NEW CASTLE COUNTY DELAWARE. THE SEVERE THUNDERSTORM WATCH AREA IS ALONG AND 75 STATUTE MILES EITHER SIDE OF A LINE FROM 15 MILES WEST OF WILMINGTON DELAWARE TO 30 MILES EAST OF ALLENTOWN PENNSYLVANIA. AT 600 PM WEATHER SERVICE RADAR SHOWED AN AREA OF SHOWERS AND THUNDERSTORMS FROM SCRANTON PENNSYLVANIA SOUTHWEST TO NEAR YORK PENNSYLVANIA. THESE STORMS WERE MOVING TO THE EAST A 30 MPH. THESE STORMS COULD REACH NEW CASTLE COUNTY BY 6 PM. REMEMBER...A SEVERE THUNDERSTORM WATCH MEANS CONDITIONS ARE FAVORABLE FOR SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH AREA. PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR THREATENING* WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS AND POSSIBLE WARNING. STAY TUNED TO NOAA WEATHER RADIO OR LOCAL RADIO AND TELEVISION STATIONS FOR LATER STATEMENTS OR POSSIBLE WARNING. VAUGHAN
Special weather statement, Jul 13, 6:35 PM EDT, 1 hour 12 minutes before
DEZ003-140015- SPECIAL WEATHER STATEMENT...CORRECTION NATIONAL WEATHER SERVICE WILMINGTON DE 610 PM EDT SAT JUL 13 1991 ...SEVERE THUNDERSTORM WATCH FOR MOST OF EASTERN PENNSYLVANIA...ALL OF SOUTHERN NEW JERSEY...AND NORTHERN DELAWARE UNTIL 10 PM EDT... A SEVERE THUNDERSTORM WATCH HAS BEEN PLACED IN EFFECT FOR NEW CASTLE COUNTY DELAWARE. THE SEVERE THUNDERSTORM WATCH AREA IS ALONG AND 75 STATUTE MILES EITHER SIDE OF A LINE FROM 15 MILES WEST OF WILMINGTON DELAWARE TO 30 MILES EAST OF ALLENTOWN PENNSYLVANIA. AT 600 PM WEATHER SERVICE RADAR SHOWED AN AREA OF SHOWERS AND THUNDERSTORMS FROM SCRANTON PENNSYLVANIA SOUTHWEST TO NEAR YORK PENNSYLVANIA. THESE STORMS WERE MOVING TO THE EAST A 30 MPH. THESE STORMS COULD REACH NEW CASTLE COUNTY BY 7 PM. REMEMBER...A SEVERE THUNDERSTORM WATCH MEANS CONDITIONS ARE FAVORABLE FOR SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH AREA. PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR THREATENING WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS AND POSSIBLE WARNING. STAY TUNED TO NOAA WEATHER RADIO OR LOCAL RADIO AND TELEVISION STATIONS FOR LATER STATEMENTS OR POSSIBLE WARNING. VAUGHAN
Special weather statement, Jul 13, 6:44 PM EDT, 1 hour 3 minutes before
PAZ011-016-140000- SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE ALLENTOWN PA 640 PM EDT SAT JUL 13 1991 ...SEVERE THUNDERSTORM WATCH IN EFFECT FOR EASTERN PENNSYLVANIA AND WESTERN NEW JERSEY UNTIL 1000PM THIS EVENING... AT 640PM THIS EVENING RADAR INDICATED HEAVY THUNDERSTORMS EXTENDING FROM ALLENTOWN SOUTHWEST TO READING THEN SOUTH THROUGH EXTREME SOUTHERN BERKS COUNTY. THE HEAVIEST ACTIVITY WAS NEAR AND JUST SOUTH OF READING. MOVEMENT WAS TOWARDS THE SOUTHEAST AT AROUND 30 MPH. AS THESE THUNDERSTORMS MOVED THROUGHTHE A-B-E AIRPORT WINDS GUSTED TO 38 MPH AND HEAVY RAIN PRODUCED .38" IN 30 MINUTES. PERSONS IN SOUTHERN BERKS...LEHIGH AND NORTHAMPTON COUNTIES SHOULD BE ALERT FOR HEA!VY DOWNPOURS...GUSTY WINDS AND DANGEROUS LIGHTNING OVER THE NEXT HOUR AS THESE STORMS CONTINUE TO MOVE TOWARD THE SOUTHEAST. LOEPER
Special weather statement, Jul 13, 6:54 PM EDT, 53 minutes before
NJZ002>004-006-132350 SPECIAL WEATHER STATEMENT AND RADAR SUMMARY NATIONAL WEATHER SERVICE ATLANTIC CITY NJ 640 PM EDT SAT JUL 13 1991 ...SEVERE THUNDERSTORM WATCH IN EFFECT FOR SOUTHERN NEW JERSEY AND THE ADJACENT COASTAL WATERS UNTIL 10 PM EDT... AT 632 PM...OUR WEATHER SEARCH RADAR WAS DETECTING THUNDERSTORMS WITH VERY HEAVY RAIN AND POSSIBLE HAIL IN EASTERN PENNSYLVANIA JUST TO THE SOUTH OF ALLENTOWN AND IN THE LOWER SUSQUEHANNA VALLEY OF PENNSYLVANIA BETWEEN LANCASTER AND POTTSTOWN. THESE STORMS WERE WITHIN AN AREA OF SHOWERS AND THUNDERSTORMS WITH HEAVY RAIN EXTENDING FROM STROUDSBURG IN NORTHEAST PENNSYLVANIA ACROSS EASTERN PENNSYLVANIA...MIDDLE AND LOWER SUSQUEHANNA VALLEY OF PENNSYLVANIA AND WAS MOVING INTO WARREN AND HUNTERDON COUNTIES OF WESTERN NORTHERN NEW JERSEY. MOVEMENT WAS EAST AT 30 TO 35 MILES AN HOUR. SHOWERS AND THUNDERSTORMS...SOME WITH HEAVY RAIN...WERE SCATTERED ACROSS COASTAL CENTRAL AND SOUTHERN NEW JERSEY AND THE COASTAL WATERS. ALSO OVER THE OCEAN FROM 70 TO 175 MILES EAST OF THE NEW JERSEY COAST. MOVEMENT WAS EAST AT 25 MILES AN HOUR. ADDITIONAL HEAVY RAINFALL MAY CAUSE FLOODING IN POOR DRAINAGE AREAS AND CAUSE LARGE STANDING PUDDLES ON ROADWAYS. CENTRAL AND SOUTHERN NEW JERSEY AND COASTAL SECTIONS HAVE ALREADY RECEIVED ANYWHERE FROM TWO TO THIRTEEN INCHES OF RAIN ALREADY. REPORTS INDICATED MANY ROADS HAVE BEEN CLOSWD DUE TO FLOODING IN HEAVY RAINS. REMEMBER...A SEVERE THUNDERSTORM WATCH MEANS CONDITIONS ARE FAVORABLE FOR SEVERE THUNDERSTORM DEVELOPMENT IN AND CLOSE TO THE WATCH AREA. BE PREPARED TO SEEK SHETER IF THREATENING WEATHER APPROACHES. STAYED TUNED TO NOAA WEATHER RADIO OR LOCAL RADIO AND TELEVISION STATIONS F9OR LATER STATEMENTS OR POSSIBLE WARNINGS. FXD/JH
Special weather statement, Jul 13, 7:28 PM EDT, 19 minutes before
PAZ011-016-140100- SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE ALLENTOWN PA 720 PM EDT SAT JUL 13 1991 ...SEVERE THUNDERSTORM WATCH CANCELLED FOR EASTERN PENNSYLVANIA... AT 720PM THIS EVENING RADAR INDICATED THUNDERSTORMS OVER EXTREME SOUTHERN LEHIGH AND NORTHAMPTON COUNTIES. THESES THUNDERSTORMS ARE DECREASING IN INTENSITY AS THEY CONTINUE TO MOVE TOWARD THE EAST SOUTH EAST AT 25 MPH. A CHANCE SHOWERS AND THUNDERSTORMS WILL CONTINUE TO EWXSIST THROUGH LATE THIS EVENING BUT NO SEVERE WEATHER IS EXPECTED. UNLESS CONDITIONS WARRANT...THIS WILL BE THE LAST STATEMENT CONCERNING THIS WEATHER EVENT. LOEPER
Special weather statement, Jul 13, 7:36 PM EDT, 11 minutes before
PAZ012-NJZ002-140030-
SPECIAL WEATHER STATEMENT - SEVERE THUNDERSTORM WATCH
NATIONAL WEATHER SERVICE PHILADELPHIA PA
730 PM EDT SAT JUL 13 1991
...SEVERE THUNDERSTORM WATCH REMAINS IN EFFECT TILL 10 PM FOR
EXTREME SOUTHEAST PENNSYLVANIA AND ALL OF SOUTHERN NEW JERSEY...
...SEVERE THUNDERSTORM WATCH CANCELLED FOR THE REMAINDER OF EASTERN
PENNSYLVANIA...
AT 720 PM WEATHER SERVICE RADAR SHOWED THUNDERSTORMS...SOME OF
WHICH MAY BE SEVERE...MOVING THROUGH CHESTER...MONTGOMERY...AND
DELAWARE COUNTIES OF SOUTHEAST PENNSYLVANIA. THESE THUNDERSTORMS
WILL CONTINUE TO THREATEN SOUTHEAST PENNSYLVANIA AND NEARBY PORTIONS
OF SOUTHERN NEW JERSEY DURING THE NEXT SEVERAL HOURS.
SEVERE TwHUNDERSTORMS ARE NO LONGER EXPECTED IN THE EAST CENTRAL...
NORTHEAST METROPOLITAN...POCONO...LOWER OR MIDDLE SUSQUEHANNA REGIONS
OF PENNSYLVANIA.
SPThe office that day
Everything else NWS Philadelphia/Mount Holly issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jul 13, 7:58 AM EDT | Flash Flood Warning | PHI | Philadelphia | 92 min |
| Jul 13, 6:52 PM EDT | Severe Thunderstorm Warning | PHI | Chester, Montgomery | 53 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.