Alert archive / Pennsylvania / Severe Thunderstorm Warnings in 2026
Severe Thunderstorm Warning 299, NWS Philadelphia/Mount Holly
NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Aug 10, 2026, 4:46 PM EDT for New Castle County, Delaware; Chester County, Delaware County, Pennsylvania. It was in force for 20 min. No storm report in the archive falls inside the area while it was in force.
The area
The outline as issued.
The facts
- Issued
- Aug 10, 2026, 4:46 PM EDT (20:46 UTC)
- Expired
- Aug 10, 2026, 5:06 PM EDT
- In force
- 20 min
- Issued by
- NWS Philadelphia/Mount Holly
- Area
- Storm-based polygon
- Hail
- 0.75 in
- Wind
- 60.0 mph
Counties New Castle County, DE, Chester County, PA, Delaware County, PA
The radar
The Philadelphia radar (KDIX), 91 km from the middle of the area, began a volume at 20:48 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.
The watch it was issued in
The SPC watch in force over the same counties when this warning went out.
| Issued | Product | Office | Lasted |
|---|---|---|---|
| Aug 10, 2:10 PM EDT | Severe Thunderstorm Watch | SPC | 6 hr |
The nearest sounding before it
Washington/Dulle, VA (KIAD), launched 12:00Z, 8.8 hours before the alert went out and 199 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
- 682 J/kg
- Mixed-layer CIN
- -91 J/kg
- Mixed-layer LCL
- 1254 m above ground
- 0-6 km bulk shear
- 29 kt
- 0-1 km storm-relative helicity
- -34 m²/s²
- 0-3 km storm-relative helicity
- -2 m²/s²
- Significant tornado parameter
- -0.0
- Supercell composite
- -0.6
The text
As transmitted.
781
WUUS51 KPHI 102046
SVRPHI
DEC003-PAC029-045-102130-
/O.NEW.KPHI.SV.W.0299.260810T2046Z-260810T2130Z/
BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Mount Holly NJ
446 PM EDT Mon Aug 10 2026
The National Weather Service in Mount Holly NJ has issued a
* Severe Thunderstorm Warning for...
North central New Castle County in northern Delaware...
Southeastern Chester County in southeastern Pennsylvania...
Delaware County in southeastern Pennsylvania...
* Until 530 PM EDT.
* At 446 PM EDT, a severe thunderstorm was located over Marshallton,
or near West Chester, 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...
West Chester, Chester, Westtown, Downingtown, Swarthmore, Kennett
Square, Cheyney, Elam, Marshallton, Trout Lake, Chelsea, Radnor
Township, Gradyville, Broomall, Newtown Square, Chester Township,
Lima, Nether Providence Township, Paoli, and Philadelphia
International Arpt.
This includes the following highways...
Interstate 95 in Pennsylvania between mile markers 1 and 9.
Interstate 476 in Pennsylvania between mile markers 0 and 14.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
For your protection move to an interior room on the lowest floor of a
building.
To report severe weather, contact your nearest law enforcement
agency. They will send your report to the National Weather Service
office in Mount Holly NJ.
&&
LAT...LON 4000 7579 4007 7540 4007 7536 4006 7535
4003 7533 3985 7529 3985 7533 3983 7537
3979 7577
TIME...MOT...LOC 2046Z 266DEG 24KT 3992 7569
HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...0.75 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH
$$
MPS2 follow-up statements
557
WWUS51 KPHI 102100
SVSPHI
Severe Weather Statement
National Weather Service Mount Holly NJ
500 PM EDT Mon Aug 10 2026
DEC003-102110-
/O.CAN.KPHI.SV.W.0299.000000T0000Z-260810T2130Z/
New Castle DE-
500 PM EDT Mon Aug 10 2026
...THE SEVERE THUNDERSTORM WARNING FOR NORTH CENTRAL NEW CASTLE
COUNTY IS CANCELLED...
The severe thunderstorm which prompted the warning has moved out of
the warned area. Therefore, the warning has been cancelled.
A Severe Thunderstorm Watch remains in effect until 900 PM EDT for
southeastern Pennsylvania.
LAT...LON 3986 7563 4002 7569 4007 7540 4007 7536
4006 7535 4003 7533 3990 7530
TIME...MOT...LOC 2100Z 252DEG 24KT 3997 7558
$$
PAC029-045-102130-
/O.CON.KPHI.SV.W.0299.000000T0000Z-260810T2130Z/
Chester PA-Delaware PA-
500 PM EDT Mon Aug 10 2026
...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 530 PM EDT
FOR EAST CENTRAL CHESTER AND CENTRAL DELAWARE COUNTIES...
At 500 PM EDT, a severe thunderstorm was located over West Chester,
moving east at 25 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...
West Chester, Westtown, Downingtown, Swarthmore, Cheyney, Lima, Trout
Lake, Radnor Township, Gradyville, Nether Providence Township,
Broomall, Paoli, Newtown Square, Concordville, Drexel Hill, Darby
Township, West Goshen, Glenolden, Clifton Heights, and Media.
This includes Interstate 476 in Pennsylvania between mile markers 2
and 14.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
For your protection move to an interior room on the lowest floor of a
building.
To report severe weather contact your nearest law enforcement agency.
They will send your report to the National Weather Service office in
Mount Holly NJ.
&&
LAT...LON 3986 7563 4002 7569 4007 7540 4007 7536
4006 7535 4003 7533 3990 7530
TIME...MOT...LOC 2100Z 252DEG 24KT 3997 7558
HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...0.75 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH
$$
MPS861
WWUS51 KPHI 102106
SVSPHI
Severe Weather Statement
National Weather Service Mount Holly NJ
506 PM EDT Mon Aug 10 2026
PAC029-045-102116-
/O.CAN.KPHI.SV.W.0299.000000T0000Z-260810T2130Z/
Chester PA-Delaware PA-
506 PM EDT Mon Aug 10 2026
...THE SEVERE THUNDERSTORM WARNING FOR EAST CENTRAL CHESTER AND
CENTRAL DELAWARE COUNTIES IS CANCELLED...
The storm which prompted the warning has weakened below severe
limits, and no longer poses an immediate threat to life or property.
Therefore, the warning has been cancelled.
A Severe Thunderstorm Watch remains in effect until 900 PM EDT for
southeastern Pennsylvania.
To report severe weather, contact your nearest law enforcement
agency. They will relay your report to the National Weather Service
Mount Holly NJ.
LAT...LON 3986 7563 4002 7569 4007 7540 4007 7536
4006 7535 4003 7533 3990 7530
TIME...MOT...LOC 2103Z 266DEG 24KT 3997 7553
$$
MPSThe office that day
Everything else NWS Philadelphia/Mount Holly issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 10, 4:39 PM EDT | Severe Thunderstorm Warning | PHI | New Castle | 66 min |
| Aug 10, 5:36 PM EDT | Severe Thunderstorm Warning | PHI | Kent, New Castle, Sussex | 39 min |
| Aug 10, 6:07 PM EDT | Severe Thunderstorm Warning | PHI | Kent, New Castle, Sussex | 38 min |
| Aug 10, 6:22 PM EDT | Severe Thunderstorm Warning | PHI | Sussex | 23 min |
| Aug 10, 7:04 PM EDT | Severe Thunderstorm Warning | PHI | Sussex | 41 min |
| Aug 10, 3:21 PM EDT | Severe Thunderstorm Warning | PHI | Carbon, Lehigh, Monroe, Northampton | 39 min |
| Aug 10, 3:50 PM EDT | Severe Thunderstorm Warning | PHI | Carbon, Lehigh, Northampton | 40 min |
| Aug 10, 4:02 PM EDT | Severe Thunderstorm Warning | PHI | Monroe, Northampton | 43 min |
Nearby
Severe Thunderstorm Warnings in Pennsylvania, 2026Severe Thunderstorm Warnings in Delaware, 2026Every severe thunderstorm warning in 2026
Sources
The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.