Alert archive / Pennsylvania / Severe Thunderstorm Warnings in 1991
Severe Thunderstorm Warning 40, NWS Philadelphia/Mount Holly
NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Aug 3, 1991, 7:04 PM EDT for Chester County, Delaware County, Pennsylvania. It was in force for 26 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
- Aug 3, 1991, 7:04 PM EDT (23:04 UTC)
- Expired
- Aug 3, 1991, 7:30 PM EDT
- In force
- 26 min
- Issued by
- NWS Philadelphia/Mount Holly
- Area
- Whole counties
Counties Chester County, PA, Delaware County, PA
What was reported inside it
| Time | Report | Where | Remark |
|---|---|---|---|
| Aug 3, 7:05 PM EDT | Hail 1 | 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, 11.1 hours before the alert went out and 107 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
- 250 J/kg
- Mixed-layer CIN
- -186 J/kg
- Mixed-layer LCL
- 1239 m above ground
- 0-6 km bulk shear
- 31 kt
- 0-1 km storm-relative helicity
- 17 m²/s²
- 0-3 km storm-relative helicity
- 76 m²/s²
- Significant tornado parameter
- -0.0
- Supercell composite
- -0.7
The text
As transmitted, in the capitals the NWS used until 2016.
000 TTAA00 KPHL 032303 SVRPHL PAC029-045-032330- BULLETIN - IMMEDIATE BROADCAST REQUESTED SEVERE THUNDERSTORM WARNING NATIONAL WEATHER SERVICE PHILADELPHIA PA 704 PM EDT SAT AUG 3 1991 THE NATIONAL WEATHER SERVICE IN PHILADELPHIA HAS ISSUED A SEVERE THUNDERSTORM WARNING EFFECTIVE UNTIL 730 PM EDT FOR PEOPLE IN THE FOLLOWING LOCATIONS... IN SOUTHEAST PENNSYLVANIA ...EASTERN CHESTER COUNTY...DELAWARE COUNTY AT 655 PM A WEATHER SERVICE SPOTTER REPORTED 3/4 INCH HAIL IN DOWNINGTOWN PENNSYLVANIA. THE THUNDERSTORM THAT PRODUCED THIS HAIL IN CENTRAL CHESTER COUNTY WAS MOVING EAST AROUND 15 MPH. GUSTY WINDS AND HAIL MAY ACCOMPANY THIS THUNDERSTORM AS IT MOVES EAST THROUGH CHESTER COUNTY INTO DELAWARE COUNTY. THIS IS A DANGEROUS STORM. 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.
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, Aug 3, 4:23 PM EDT, 2 hours 41 minutes before
NJZ002>004-032130 SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE ATLANTIC CITY NJ 410 PM EDT SAT AUG 3 1991 AT 410 PM...THE ATLANTIC CITY WEATHER RADAR SHOWED A LARGE THUNDER- STORM OVER BARNEGAT IN OCEAN COUNTY OF SOUTHERN NEW JERSEY. THIS STORM IS MOVING TOWARD THE EAST AT 10 MILES AN HOUR. VERY HEAVY RAINS...DANGEROUS LIGHTNING AND BRIEF BUT STRONG WINDS ARE POSSIBLE WITH THIS STORM. PERSONS ON THE BEACHES OR ON THE OPEN OCEAN WILL HAVE fTO WATCH FOR THIS STORM AND TAKE COVER WHEN MOVES INTO YOUR AREA. MCDONALD
Special weather statement, Aug 3, 4:31 PM EDT, 2 hours 33 minutes before
PAZ007>12-016-032200-
SPECIAL WEATHER STATEMENT - THUNDERSTORM
NATIONAL WEATHER SERVICE PHILADELPHIA PA
430 PM EST SAT AUG 3 1991
...THUNDERSTORM NEAR PENNSYLVANIA...DELAWARE BORDER MOVING TOWARD
WESTERN SALEM AND SOUTHWEST GLOUCESTER COUNTIES IN NEW JERSEY...
AT 430 PM WEATHER SERVICE RADAR SHOWED A THUNDERSTORM IN NORTHERN
DELAWARE NEAR THE PENNSYLVANIA BORDER. THIS THUNDERSTORM WAS MOVING
VERY SLOWLY EAST AND MAY BE PRODUCING SOME LOCALLY HEAVY RAIN. GUSTY
WINDS AND CLOUD TO GROUND LIGHTNING MAY ALSO BE ACCOMPANYING THIS
THUNDERSTORM.
THE THUNDERSTORM WILL CONTINUE TO MOVE SLOWLY EAST AND WILL
REACH SALEM OR SOUTHWEST GLOUCESTER COUNTY IN NEW JERSEY BEFORE 5 PM.
PERSONS ENGAGED IN OUTDOOR ACTIVITIES IN THESE TWO COUNTIES OF
NEW JERSEY SHOULD BE ALERT FOR THE APPROACH OF THIS STORM AND READY TO
MOVE INDOORS IF NECESSARY.Special weather statement, Aug 3, 6:54 PM EDT, 10 minutes before
PAZ007>12-016-032200-
SPECIAL WEATHER STATEMENT - THUNDERSTORMS IN PHILA AREA
NATIONAL WEATHER SERVICE PHILADELPHIA PA
650 PM EST SAT AUG 3 1991
...THUNDERSTORMS MOVING INTO PHILADELPHIA AREA FROM THE WEST...
AT 645 PM WEATHER SERVICE RADAR SHOWED THUNDERSTORMS FROM CENTRAL
CHESTER COUNTY PENNSYLVANIA TO NORTHERN CHESAPEAKE BAY TO NEAR
BALTIMORE MARYLAND. THESE THUNDERSTORMS WERE MOVING EAST AROUND 15
MPH AND WILL AFFECT PARTS SOUTHEASTERN PENNSYLVANIA UNTIL AROUND 730
PM. THESE THUNDERSTORMS MAY CAUSE LOCALLY HEAVY RAIN AND GUSTY
WINDS...AND MAY BE ACCOMPANIED BY DANGEROUS CLOUD TO GROUND LIGHTNING.
IF OUT OF DOORS WHEN THUNDERSTORMS APPROACH...SEEK SHELTER IN
A NEARBY BUIL DING OR IN YOUR CAR.
SPSpecial weather statement, Aug 3, 7:04 PM EDT, 0 minutes before
DEZ003-002-001-040200- SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE WILMINGTON DE 701 PM EDT SAT AUG 3 1991 AT 7PM EDT RADAR SHOWS A THUNDERSTORM WITH HEAVY RAIN JUST WEST OF NORTHERN NEW CASTLE COUNTY OF DELAWARE. THIS STORM IS MOVING SOUTHEASTERLY AT ABOUT 30 MPH AND WILL AFFECT PORTIONS OF NEW CASTLE COUNTY DURING THE NEXT HOUR. IF THIS STORM PASSES YOUR AREA...YOU CAN EXPECT LOCALLY HEAVY RAIN BRIEF GUSTY WINDS IN EXCESS OF 40 MPH AND DANGEROUS LIGHTNING. BOATERS ON THE UPPER DELAWARE BAY SHOULD STAY ALERT FOR AND AVOID THIS STORM. ANOTHER AREA OF THUNDERSTORMS ARE OVER THE UPPER CHESAPEAKE BAY AND WILL LIKELY MOVE INTO PORTIONS OF CENTRAL DELAWARE BETWEEN 8 AND 9 PM SEDT THIS EVEING. ADDITIONAL STATEMENTS WILL BE ISSUED AS REQUIRED BY CONDITIONS. CKD
The office that day
Everything else NWS Philadelphia/Mount Holly issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 3, 7:25 PM EDT | Severe Thunderstorm Warning | PHI | Philadelphia | 50 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.