Alert archive / Delaware / Severe Thunderstorm Warnings in 2011
Severe Thunderstorm Warning 247, NWS Philadelphia/Mount Holly
NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Aug 18, 2011, 6:39 PM EDT for New Castle County, Delaware; Chester County, Pennsylvania. It was in force for 66 min. 2 reports came from inside the area while it was in force.
The area
The outline as issued, with what was reported inside it.
The facts
- Issued
- Aug 18, 2011, 6:39 PM EDT (22:39 UTC)
- Expired
- Aug 18, 2011, 7:45 PM EDT
- In force
- 66 min
- Issued by
- NWS Philadelphia/Mount Holly
- Area
- Storm-based polygon
Counties New Castle County, DE, Chester County, PA
The radar
The Dover AFB radar (KDOX), 121 km from the middle of the area, began a volume at 22:40 UTC, the scan nearest the moment this went out.
Open the radar archive at this moment
The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.
What was reported inside it
| Time | Report | Where | Remark |
|---|---|---|---|
| Aug 18, 7:00 PM EDT | TSTM WND DMG | Hockessin, DE | TREE LIMBS DOWN. |
| Aug 18, 7:00 PM EDT | HAIL 1.25 | Ladenberg, PA |
Local storm reports filed while the alert was in force, from inside its polygon or its counties.
The nearest sounding before it
Phillips Aaf/Abe, MD (KAPG), launched 12:00Z, 10.7 hours before the alert went out and 44 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
- 780 J/kg
- Mixed-layer CIN
- -64 J/kg
- Mixed-layer LCL
- 1022 m above ground
- 0-6 km bulk shear
- 16 kt
- 0-1 km storm-relative helicity
- 83 m²/s²
- 0-3 km storm-relative helicity
- 143 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted, in the capitals the NWS used until 2016.
339
WUUS51 KPHI 182239
SVRPHI
DEC003-PAC029-182345-
/O.NEW.KPHI.SV.W.0247.110818T2239Z-110818T2345Z/
BULLETIN - EAS ACTIVATION REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
639 PM EDT THU AUG 18 2011
THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ HAS ISSUED A
* SEVERE THUNDERSTORM WARNING FOR...
NORTH CENTRAL NEW CASTLE COUNTY IN NORTHERN DELAWARE...
SOUTHWESTERN CHESTER COUNTY IN SOUTHEAST PENNSYLVANIA...
* UNTIL 745 PM EDT
* AT 637 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
SEVERE THUNDERSTORM CAPABLE OF PRODUCING QUARTER SIZE HAIL...AND
DAMAGING WINDS IN EXCESS OF 60 MPH. THIS STORM WAS LOCATED NEAR
MOUNT VERNON...OR 15 MILES NORTHWEST OF NEWARK...AND MOVING EAST AT
10 MPH.
* THE SEVERE THUNDERSTORM WILL BE NEAR...
HOMEVILLE AROUND 645 PM EDT...
COCHRANVILLE AROUND 710 PM EDT...
WEST GROVE AROUND 730 PM EDT...
KENNETT SQUARE...LADENBERG...7 MILES NORTHWEST OF HOCKESSIN AND 7
MILES WEST OF ASHLAND AROUND 745 PM EDT...
PRECAUTIONARY/PREPAREDNESS ACTIONS...
THIS IS A DANGEROUS STORM. IF YOU ARE IN ITS PATH...PREPARE
IMMEDIATELY FOR DAMAGING WINDS...DESTRUCTIVE HAIL...AND DEADLY CLOUD
TO GROUND LIGHTNING. PEOPLE OUTSIDE SHOULD MOVE TO A SHELTER...
PREFERABLY INSIDE A STRONG BUILDING BUT AWAY FROM WINDOWS.
PLEASE REPORT HAIL OR STRONG WINDS TO THE NATIONAL WEATHER SERVICE BY
CALLING TOLL FREE...1-877-633-6772...WHEN YOU CAN DO SO SAFELY.
&&
LAT...LON 3984 7603 3985 7603 3987 7601 3998 7568
3978 7560 3974 7603 3983 7605
TIME...MOT...LOC 2239Z 256DEG 9KT 3980 7600
$$
HEAVENER3 follow-up statements
217 WWUS51 KPHI 182305 SVSPHI SEVERE WEATHER STATEMENT NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 705 PM EDT THU AUG 18 2011 DEC003-PAC029-182345- /O.CON.KPHI.SV.W.0247.000000T0000Z-110818T2345Z/ CHESTER PA-NEW CASTLE DE- 705 PM EDT THU AUG 18 2011 ...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 745 PM EDT FOR NORTH CENTRAL NEW CASTLE AND CENTRAL CHESTER COUNTIES... AT 702 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR CONTINUED TO INDICATE A SEVERE THUNDERSTORM CAPABLE OF PRODUCING QUARTER SIZE HAIL...AND DAMAGING WINDS IN EXCESS OF 60 MPH. THIS STORM WAS LOCATED NEAR WEST GROVE...OR 13 MILES NORTHWEST OF NEWARK...MOVING EAST AT 10 MPH. THE SEVERE THUNDERSTORM WILL BE NEAR... COCHRANVILLE BY 710 PM EDT... WEST GROVE BY 730 PM EDT... AVONDALE...TOUGHKENAMON...KENNETT SQUARE AND LADENBERG BY 745 PM EDT... PRECAUTIONARY/PREPAREDNESS ACTIONS... PLEASE REPORT HAIL OR STRONG WINDS TO THE NATIONAL WEATHER SERVICE BY CALLING TOLL FREE...1-877-633-6772...WHEN YOU CAN DO SO SAFELY. && LAT...LON 3976 7588 3988 7598 3998 7568 3978 7560 TIME...MOT...LOC 2305Z 256DEG 9KT 3982 7592 $$ HEAVENER
729 WWUS51 KPHI 182321 SVSPHI SEVERE WEATHER STATEMENT NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 721 PM EDT THU AUG 18 2011 DEC003-PAC029-182345- /O.CON.KPHI.SV.W.0247.000000T0000Z-110818T2345Z/ CHESTER PA-NEW CASTLE DE- 721 PM EDT THU AUG 18 2011 ...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 745 PM EDT FOR NORTH CENTRAL NEW CASTLE AND CENTRAL CHESTER COUNTIES... AT 719 PM EDT...THE PUBLIC REPORTED A SEVERE THUNDERSTORM CAPABLE OF PRODUCING QUARTER SIZE HAIL...AND DAMAGING WINDS IN EXCESS OF 60 MPH. THIS STORM WAS LOCATED NEAR AVONDALE...OR 12 MILES NORTHWEST OF NEWARK...MOVING EAST AT 10 MPH. THE SEVERE THUNDERSTORM WILL BE NEAR... AVONDALE...TOUGHKENAMON...KENNETT SQUARE AND 7 MILES NORTHWEST OF HOCKESSIN BY 745 PM EDT... PRECAUTIONARY/PREPAREDNESS ACTIONS... HAIL UP TO 1 INCH IN DIAMETER HAS BEEN REPORTED IN LANDENBERG WITH THIS STORM. IF YOU ARE IN THE PATH OF THE STORM...TAKE IMMEDIATE ACTION TO PROTECT LIFE AND PROPERTY. PLEASE REPORT HAIL OR STRONG WINDS TO THE NATIONAL WEATHER SERVICE BY CALLING TOLL FREE...1-877-633-6772...WHEN YOU CAN DO SO SAFELY. && LAT...LON 3977 7576 3993 7583 3998 7568 3978 7560 TIME...MOT...LOC 2320Z 256DEG 9KT 3983 7587 $$ HEAVENER
444 WWUS51 KPHI 182338 SVSPHI SEVERE WEATHER STATEMENT NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 738 PM EDT THU AUG 18 2011 DEC003-PAC029-182349- /O.EXP.KPHI.SV.W.0247.000000T0000Z-110818T2345Z/ CHESTER PA-NEW CASTLE DE- 738 PM EDT THU AUG 18 2011 ...THE SEVERE THUNDERSTORM WARNING FOR NORTH CENTRAL NEW CASTLE AND CENTRAL CHESTER COUNTIES WILL EXPIRE AT 745 PM EDT... PLEASE REPORT HAIL OR STRONG WINDS TO THE NATIONAL WEATHER SERVICE BY CALLING TOLL FREE...1-877-633-6772...WHEN YOU CAN DO SO SAFELY. LAT...LON 3977 7576 3993 7583 3998 7568 3978 7560 TIME...MOT...LOC 2339Z 256DEG 9KT 3984 7581 $$ HEAVENER
The office that day
Everything else NWS Philadelphia/Mount Holly issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 18, 5:45 AM EDT | Special Weather Statement | PHI | New Castle | 60 min |
| Aug 18, 6:35 AM EDT | Areal Flood Advisory | PHI | New Castle | 3 hr |
| Aug 18, 3:12 PM EDT | Flash Flood Watch | PHI | New Castle | 29 hr |
| Aug 18, 5:48 PM EDT | Severe Thunderstorm Warning | PHI | New Castle | 57 min |
| Aug 18, 6:44 PM EDT | Special Weather Statement | PHI | New Castle | 61 min |
| Aug 18, 7:14 PM EDT | Severe Thunderstorm Warning | PHI | New Castle | 50 min |
| Aug 18, 7:37 PM EDT | Severe Thunderstorm Warning | PHI | New Castle | 53 min |
| Aug 18, 2:57 AM EDT | Special Weather Statement | PHI | Berks | 63 min |
| Aug 18, 3:53 AM EDT | Special Weather Statement | PHI | Berks | 52 min |
| Aug 18, 4:48 AM EDT | Special Weather Statement | PHI | Chester, Montgomery | 57 min |
| Aug 18, 6:04 AM EDT | Special Weather Statement | PHI | Berks, Chester | 41 min |
| Aug 18, 7:29 AM EDT | Special Weather Statement | PHI | Bucks, Delaware, Montgomery, Philadelphia | 61 min |
| Aug 18, 8:16 AM EDT | Special Weather Statement | PHI | Philadelphia | 59 min |
| Aug 18, 9:29 AM EDT | Areal Flood Advisory | PHI | Delaware | 2 hr |
| Aug 18, 5:30 PM EDT | Special Weather Statement | PHI | Monroe | 60 min |
| Aug 18, 6:18 PM EDT | Special Weather Statement | PHI | Chester | 57 min |
| Aug 18, 6:59 PM EDT | Flash Flood Warning | PHI | Chester | 2 hr |
| Aug 18, 7:28 PM EDT | Special Weather Statement | PHI | Chester | 62 min |
| Aug 18, 7:31 PM EDT | Special Weather Statement | PHI | Monroe | 59 min |
| Aug 18, 7:47 PM EDT | Areal Flood Advisory | PHI | Carbon, Monroe, Northampton | 3 hr |
| Aug 18, 7:58 PM EDT | Severe Thunderstorm Warning | PHI | Bucks, Montgomery | 31 min |
| Aug 18, 7:59 PM EDT | Severe Thunderstorm Warning | PHI | Bucks, Delaware, Montgomery, Philadelphia | 61 min |
Nearby
Severe Thunderstorm Warnings in Delaware, 2011Severe Thunderstorm Warnings in Pennsylvania, 2011Every severe thunderstorm warning in 2011
Sources
The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.