Alert archive / Pennsylvania / Severe Thunderstorm Warnings in 2021
Severe Thunderstorm Warning 245, NWS Philadelphia/Mount Holly
NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Aug 10, 2021, 7:54 PM EDT for Chester County, Pennsylvania; New Castle County, Delaware. It was in force for 51 min. 7 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 10, 2021, 7:54 PM EDT (23:54 UTC)
- Expired
- Aug 10, 2021, 8:45 PM EDT
- In force
- 51 min
- Issued by
- NWS Philadelphia/Mount Holly
- Area
- Storm-based polygon
- Damage threat
- Considerable
- Hail
- 0.75 in
- Wind
- 70.0 mph
Counties New Castle County, DE, Chester County, PA
The radar
The Dover AFB radar (KDOX), 118 km from the middle of the area, began a volume at 23:53 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 10, 7:58 PM EDT | TSTM WND DMG | 2 Nne East Bradford Twp, PA | TREE DOWN ON WIRES NEAR THE INTERSECTION OF SUNSET HOLLOW RD AND GROVE RD. TIME ESTIMATED FROM RADAR. |
| Aug 10, 8:04 PM EDT | TSTM WND GST 51 | 1 Nne Penn Twp, PA | CWOP SITE AV669. |
| Aug 10, 8:05 PM EDT | TSTM WND GST 55 | West Grove, PA | DEOS GAUGE. |
| Aug 10, 8:10 PM EDT | TSTM WND DMG | Avondale, PA | DOWNED WIRES BLOCKING POMEROY AVE AT STATE ST. TIME ESTIMATED FROM RADAR. |
| Aug 10, 8:15 PM EDT | TSTM WND DMG | 2 Ne Landenberg, PA | DOWNED TREE BLOCKING ALL OF EGYPT RUN RD NEAR NEWARK RD. TIME ESTIMATED FROM RADAR. |
| Aug 10, 8:17 PM EDT | TSTM WND DMG | 1 Nnw Kennett Square, PA | DOWNED TREE LIMBS BLOCKING MOST OF UNIONVILLE RD AT GATEHOUSE DR. TIME ESTIMATED FROM RADAR. |
| Aug 10, 8:18 PM EDT | TSTM WND DMG | 2 Ene Landenberg, PA | DOWNED TREE PARTIALLY BLOCKING REYNOLDS RD NEAR SPRING BENNY RUN. TIME ESTIMATED FROM RADAR. |
Local storm reports filed while the alert was in force, from inside its polygon or its counties.
The nearest sounding before it
Washington/Dulle, VA (KIAD), launched 12:00Z, 11.9 hours before the alert went out and 155 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
- 529 J/kg
- Mixed-layer CIN
- -120 J/kg
- Mixed-layer LCL
- 1096 m above ground
- 0-6 km bulk shear
- 14 kt
- 0-1 km storm-relative helicity
- 37 m²/s²
- 0-3 km storm-relative helicity
- 65 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
138
WUUS51 KPHI 102354
SVRPHI
DEC003-PAC029-110045-
/O.NEW.KPHI.SV.W.0245.210810T2354Z-210811T0045Z/
BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Mount Holly NJ
754 PM EDT Tue Aug 10 2021
The National Weather Service in Mount Holly NJ has issued a
* Severe Thunderstorm Warning for...
Northwestern New Castle County in northern Delaware...
Southwestern Chester County in southeastern Pennsylvania...
* Until 845 PM EDT.
* At 753 PM EDT, a severe thunderstorm was located near Quarryville,
or 12 miles southeast of Willow Street, moving east at 25 mph.
HAZARD...70 mph wind gusts and penny size hail.
SOURCE...Radar indicated.
IMPACT...Expect considerable tree damage. Damage is likely to
mobile homes, roofs, and outbuildings.
* Locations impacted include...
Newark, West Chester, Coatesville, Downingtown, Kennett Square,
Oxford, Parkesburg, West Grove, Homeville, Glen Roy, Cochranville,
North Star, Mount Vernon, Marshallton, Pike Creek, Ashland,
Ladenberg, Kemblesville, Hockessin and Stanton.
This includes Interstate 95 in Delaware between mile markers 5 and 8.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
For your protection move to an interior room on the lowest floor of a
building.
This is a DANGEROUS SITUATION. This storm is producing a corridor of
very strong winds up to 70 mph. SEEK SHELTER NOW inside a sturdy
structure and stay away from windows!
&&
LAT...LON 3974 7612 3973 7610 3974 7610 3976 7606
3981 7603 3983 7604 3987 7599 3994 7598
3995 7600 3997 7598 4001 7560 3965 7565
3967 7579 3972 7579 3972 7613
TIME...MOT...LOC 2353Z 268DEG 24KT 3986 7611
THUNDERSTORM DAMAGE THREAT...CONSIDERABLE
HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...0.75 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...70 MPH
$$
SFJ3 follow-up statements
571
WWUS51 KPHI 102357
SVSPHI
Severe Weather Statement
National Weather Service Mount Holly NJ
757 PM EDT Tue Aug 10 2021
DEC003-PAC029-110045-
/O.CON.KPHI.SV.W.0245.000000T0000Z-210811T0045Z/
New Castle DE-Chester PA-
757 PM EDT Tue Aug 10 2021
...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 845 PM EDT
FOR NORTHWESTERN NEW CASTLE AND SOUTHWESTERN CHESTER COUNTIES...
At 756 PM EDT, a severe thunderstorm was located near Mount Vernon,
or 13 miles southeast of Willow Street, moving east at 30 mph.
HAZARD...70 mph wind gusts and penny size hail.
SOURCE...Radar indicated.
IMPACT...Expect considerable tree damage. Damage is likely to mobile
homes, roofs, and outbuildings.
Locations impacted include...
Newark, West Chester, Coatesville, Downingtown, Kennett Square,
Oxford, Parkesburg, West Grove, Homeville, Glen Roy, Cochranville,
North Star, Mount Vernon, Marshallton, Pike Creek, Ashland,
Landenberg, Kemblesville, Hockessin and Stanton.
This includes Interstate 95 in Delaware between mile markers 5 and 8.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
For your protection move to an interior room on the lowest floor of a
building.
&&
LAT...LON 3974 7612 3973 7610 3974 7610 3976 7606
3981 7603 3983 7604 3987 7599 3994 7598
3995 7600 3997 7598 4001 7560 3965 7565
3967 7579 3972 7579 3972 7613
TIME...MOT...LOC 2356Z 268DEG 24KT 3986 7608
THUNDERSTORM DAMAGE THREAT...CONSIDERABLE
HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...0.75 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...70 MPH
$$
SFJ481
WWUS51 KPHI 110023
SVSPHI
Severe Weather Statement
National Weather Service Mount Holly NJ
823 PM EDT Tue Aug 10 2021
DEC003-PAC029-110045-
/O.CON.KPHI.SV.W.0245.000000T0000Z-210811T0045Z/
New Castle DE-Chester PA-
823 PM EDT Tue Aug 10 2021
...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 845 PM EDT
FOR NORTHWESTERN NEW CASTLE AND SOUTH CENTRAL CHESTER COUNTIES...
At 822 PM EDT, a severe thunderstorm was located near West Grove, or
13 miles north of Newark, moving east at 30 mph.
HAZARD...60 mph wind gusts and penny size hail.
SOURCE...Radar indicated.
IMPACT...Damage to roofs, siding, trees, and power lines is
possible.
Locations impacted include...
Newark, West Chester, Coatesville, Downingtown, Kennett Square,
Parkesburg, West Grove, Cochranville, North Star, Marshallton,
Ladenberg, Pike Creek, Kemblesville, Hockessin, Ashland, Stanton,
South Coatesville, Avondale, Modena and Toughkenamon.
This includes Interstate 95 in Delaware between mile markers 5 and 8.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
For your protection move to an interior room on the lowest floor of a
building.
&&
LAT...LON 4001 7560 3965 7565 3967 7579 3972 7579
3972 7597 3998 7591
TIME...MOT...LOC 0022Z 268DEG 24KT 3987 7585
HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...0.75 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH
$$
SFJ773
WWUS51 KPHI 110039
SVSPHI
Severe Weather Statement
National Weather Service Mount Holly NJ
839 PM EDT Tue Aug 10 2021
DEC003-PAC029-110048-
/O.EXP.KPHI.SV.W.0245.000000T0000Z-210811T0045Z/
New Castle DE-Chester PA-
839 PM EDT Tue Aug 10 2021
...THE SEVERE THUNDERSTORM WARNING FOR NORTHWESTERN NEW CASTLE AND
SOUTH CENTRAL CHESTER COUNTIES WILL EXPIRE AT 845 PM EDT...
The storm which prompted the warning has moved out of the area.
Therefore, the warning will be allowed to expire. However gusty
winds are still possible with this thunderstorm.
LAT...LON 4001 7560 3965 7565 3967 7579 3972 7579
3972 7597 3998 7591
TIME...MOT...LOC 0038Z 268DEG 24KT 3987 7572
$$
SFJThe office that day
Everything else NWS Philadelphia/Mount Holly issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 9, 10:10 PM EDT | Areal Flood Advisory | PHI | Carbon | 3 hr |
| Aug 10, 3:33 AM EDT | Excessive Heat Warning | PHI | Berks, Bucks, Chester, Delaware, Lehigh, Montgomery and 2 more | 4 days |
| Aug 10, 3:33 AM EDT | Heat Advisory | PHI | Berks, Carbon, Lehigh, Monroe, Northampton | 4 days |
| Aug 10, 5:58 AM EDT | Flash Flood Warning | PHI | Bucks | 2 hr |
| Aug 10, 3:06 PM EDT | Special Weather Statement | PHI | Berks | 24 min |
| Aug 10, 3:33 PM EDT | Special Weather Statement | PHI | Berks | 27 min |
| Aug 10, 3:52 PM EDT | Special Weather Statement | PHI | Berks, Carbon, Lehigh | 23 min |
| Aug 10, 4:01 PM EDT | Severe Thunderstorm Warning | PHI | Berks, Carbon, Chester, Lehigh, Montgomery, Northampton | 44 min |
| Aug 10, 4:18 PM EDT | Areal Flood Advisory | PHI | Berks, Carbon, Lehigh | 3 hr |
| Aug 10, 4:33 PM EDT | Severe Thunderstorm Warning | PHI | Berks, Bucks, Carbon, Chester, Lehigh, Monroe and 2 more | 42 min |
| Aug 10, 5:05 PM EDT | Special Weather Statement | PHI | Northampton | 25 min |
| Aug 10, 5:09 PM EDT | Severe Thunderstorm Warning | PHI | Bucks, Montgomery, Philadelphia | 51 min |
| Aug 10, 5:11 PM EDT | Special Weather Statement | PHI | Chester, Montgomery, Philadelphia | 34 min |
| Aug 10, 5:40 PM EDT | Special Weather Statement | PHI | Chester | 35 min |
| Aug 10, 5:58 PM EDT | Special Weather Statement | PHI | Philadelphia | 32 min |
| Aug 10, 6:36 PM EDT | Severe Thunderstorm Warning | PHI | Berks, Chester | 39 min |
| Aug 10, 7:10 PM EDT | Severe Thunderstorm Warning | PHI | Berks, Chester, Montgomery | 65 min |
Nearby
Severe Thunderstorm Warnings in Pennsylvania, 2021Severe Thunderstorm Warnings in Delaware, 2021Every severe thunderstorm warning in 2021
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.