Alert archive / Pennsylvania / Severe Thunderstorm Warnings in 1991
Severe Thunderstorm Warning 33, NWS Philadelphia/Mount Holly
NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Jul 13, 1991, 6:52 PM EDT for Chester County, Montgomery County, Pennsylvania. It was in force for 53 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, 6:52 PM EDT (22:52 UTC)
- Expired
- Jul 13, 1991, 7:45 PM EDT
- In force
- 53 min
- Issued by
- NWS Philadelphia/Mount Holly
- Area
- Whole counties
Counties Chester County, PA, Montgomery County, PA
What was reported inside it
| Time | Report | Where | Remark |
|---|---|---|---|
| Jul 13, 7:30 PM EDT | Thunderstorm Wind 0 | Chester, 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, 10.9 hours before the alert went out and 115 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 132304 COR SVRPHL PAC029-091-132345- BULLETIN - IMMEDIATE BROADCAST REQUESTED...CORRECTION SEVERE THUNDERSTORM WARNING NATIONAL WEATHER SERVICE PHILADELPHIA PA 652 PM EDT SAT JUL 13 1991 THE NATIONAL WEATHER SERVICE IN PHILADELPHIA HAS ISSUED A SEVERE THUNDERSTORM WARNING EFFECTIVE UNTIL 745 PM EDT FOR PEOPLE IN THE FOLLOWING LOCATIONS... IN SOUTHEAST PENNSYLVANIA ...NORTHERN CHESTER COUNTY...MONTGOMERY COUNTY AT 650 PM EDT WEATHER SERVICE RADAR SHOWED AN AREA OF THUNDERSTORMS OVER NORTHERN CHESTER AND WESTERN MONTGOMERY COUNTIES. THESE THUNDERSTORMS WERE MOVING EAST AROUND 30 MPH AND INTENSIFYING. THESE THUNDERSTORMS MAY CONTAIN VERY STRONG GUSTY WINDS...HEAVY RAIN...AND HAIL. 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 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 LI#TTLE 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, 2:22 PM EDT, 4 hours 30 minutes before
NJZ002>004-006-071645 SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE ATLANTIC CITY NJ 215 PM EDT SAT JUL 13 1991 ...VERY HEAVY RAIN OVER LONG BEACH ISLAND... VERY HEAVY RAIN OVER LONG BEACH ISLAND SINCE 8 AM THIS MORNING HAS CAUSED URBAN AND STREET FLOODING FROM BARNEGAT LIGHT TO SHIP BOTTOM. LOVELADIES AT 215 PM REPORTED A TOTAL OF TWELVE AND A HALF INCHES OF RAIN SINCE 8 AM AND THERE MAY BE MORE ON THE WAY IN THE NEXT FEW HOURS. DRIVERS ATTEMPTING TO DRIVE TO THE ISLAND OR ON THE ISLAND BE PREPARED FOR DELAYS DUE TO THE AMOUNT OF WATER ON THE ROADWAYS. MENNELLA
Special weather statement, Jul 13, 6:13 PM EDT, 39 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 PENNSY THESE STORMS WERE MOVING TO THE EAST A 30 MPH. THESE STORMS COULD REA 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, 6:17 PM EDT, 35 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, 17 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, 8 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
The 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, 7:47 PM EDT | Severe Thunderstorm Warning | PHI | Philadelphia | 58 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.