Alert archive / Pennsylvania / Severe Thunderstorm Warnings in 2026

Severe Thunderstorm Warning 314, NWS Philadelphia/Mount Holly

August 20, 20266 counties in Pennsylvania; New Castle County, Delaware; Gloucester County, Salem County, New Jersey

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Aug 20, 2026, 5:27 PM EDT for 6 counties in Pennsylvania; New Castle County, Delaware; Gloucester County, Salem County, New Jersey. It was in force for 48 min. 5 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 20, 2026, 5:27 PM EDT (21:27 UTC)
Expired: Aug 20, 2026, 6:15 PM EDT
In force: 48 min
Issued by: NWS Philadelphia/Mount Holly
Area: Storm-based polygon
Tornado: Possible
Damage threat: Considerable
Hail: 0.75 in
Wind: 70.0 mph

Counties New Castle County, DE, Gloucester County, NJ, Salem County, NJ, Berks County, PA, Bucks County, PA, Chester County, PA, Delaware County, PA, Montgomery County, PA, Philadelphia County, PA

The radar

The Philadelphia radar (KDIX), 88 km from the middle of the area, began a volume at 21:26 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 20, 5:30 PM EDT	TSTM WND DMG	1 Nnw West Pottsgrove T, PA	Tree down near Rattlesnake Hill Rd & Manatawny Dr. Time estimated by radar.
Aug 20, 5:38 PM EDT	TSTM WND DMG	East Nantmeal Twp, PA	Trees down.
Aug 20, 5:40 PM EDT	TSTM WND DMG	Downington, PA	Report and photos via social media of at least 2 trees down along East Pennsylvania Avenue in Downingtown. One felled tree appears to have crushed a shed. Time estimated from radar.
Aug 20, 5:40 PM EDT	TORNADO	East Caln Twp, PA	A brief tornado occurred in East Caln Township. The first damage was noted just south of the intersection of East Lancaster Avenue and Quarry Road, where several small tree branches were broken. A path of more broken tree branches, some with diameters up to 5
Aug 20, 6:17 PM EDT	HAIL 0.75	1 N Plymouth Meeting, PA	Report from mPING: Dime (0.75 in.).

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

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 20, 2:31 PM EDT	Severe Thunderstorm Watch	SPC	7 hr
Aug 20, 2:58 PM EDT	Tornado Watch	SPC	7 hr

The nearest sounding before it

Washington/Dulle, VA (KIAD), launched 12:00Z, 9.5 hours before the alert went out and 200 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.

Skew-T log-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.

Mixed-layer CAPE: 97 J/kg
Mixed-layer CIN: -72 J/kg
Mixed-layer LCL: 1192 m above ground
0-6 km bulk shear: 47 kt
0-1 km storm-relative helicity: 115 m²/s²
0-3 km storm-relative helicity: 230 m²/s²
Significant tornado parameter: -0.0
Supercell composite: -0.0

Open this sounding in Storm Lab

The text

As transmitted.

862 
WUUS51 KPHI 202127
SVRPHI
DEC003-NJC015-033-PAC011-017-029-045-091-101-202215-
/O.NEW.KPHI.SV.W.0314.260820T2127Z-260820T2215Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Mount Holly NJ
Issued by National Weather Service New York NY
527 PM EDT Thu Aug 20 2026

The National Weather Service in Mount Holly NJ has issued a

* Severe Thunderstorm Warning for...
  Northern New Castle County in northern Delaware...
  Northwestern Salem County in southern New Jersey...
  Northwestern Gloucester County in southern New Jersey...
  Southeastern Berks County in eastern Pennsylvania...
  Montgomery County in southeastern Pennsylvania...
  West central Bucks County in southeastern Pennsylvania...
  Central Chester County in southeastern Pennsylvania...
  Philadelphia County in southeastern Pennsylvania...
  Delaware County in southeastern Pennsylvania...

* Until 615 PM EDT.

* At 527 PM EDT, severe thunderstorms were located along a line
  extending from Bechtelsville to Marshallton to Glen Westover,
  moving east at 40 mph.

  HAZARD...70 mph wind gusts.

  SOURCE...Trained weather spotters.

  IMPACT...Expect considerable tree damage. Damage is likely to 
           mobile homes, roofs, and outbuildings.

* Locations impacted include...
  Philadelphia, Camden, Wilmington, Newark, West Chester, Norristown,
  Chester, Pottstown, West Deptford, Phoenixville, Lansdale, West
  Norriton, East Norriton, Pennsville, and Yeadon.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Tornado Watch remains in effect until 1000 PM EDT for northern
Delaware...southern New Jersey...and southeastern Pennsylvania.

Remain alert for a possible tornado! Tornadoes can develop quickly
from severe thunderstorms. If you spot a tornado go at once into the
basement or small central room in a sturdy structure.

For your protection move to an interior room on the lowest floor of a
building.

A Tornado Watch remains in effect until 1000 PM EDT for northern
Delaware...southern New Jersey...and southeastern Pennsylvania.

&&

LAT...LON 3994 7574 4039 7575 4038 7513 3997 7510
      3995 7514 3990 7513 3989 7514 3988 7513
      3967 7524 3965 7579 3972 7579 3972 7587
TIME...MOT...LOC 2127Z 272DEG 34KT 4038 7566 3994 7565 3972 7577 

TORNADO...POSSIBLE
THUNDERSTORM DAMAGE THREAT...CONSIDERABLE
HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...<.75 IN
WIND THREAT...OBSERVED
MAX WIND GUST...70 MPH

$$

DeSilva

1 follow-up statement

493 
WWUS51 KPHI 202153
SVSPHI

Severe Weather Statement
National Weather Service Mount Holly NJ
Issued by National Weather Service New York NY
553 PM EDT Thu Aug 20 2026

PAC011-202203-
/O.CAN.KPHI.SV.W.0314.000000T0000Z-260820T2215Z/
Berks PA-
553 PM EDT Thu Aug 20 2026

...THE SEVERE THUNDERSTORM WARNING FOR SOUTHEASTERN BERKS COUNTY IS
CANCELLED...

The storms which prompted the warning have moved out of the warned 
area. Therefore, the warning has been cancelled.

A Tornado Watch remains in effect until 1000 PM EDT for northern
Delaware...southern New Jersey...and southeastern Pennsylvania.

LAT...LON 3993 7570 4028 7562 4031 7554 4032 7513
      3997 7510 3995 7514 3988 7513 3967 7524
      3965 7579
TIME...MOT...LOC 2153Z 267DEG 39KT 4036 7541 3992 7540 3970 7552 

$$

DEC003-NJC015-033-PAC017-029-045-091-101-202215-
/O.CON.KPHI.SV.W.0314.000000T0000Z-260820T2215Z/
New Castle DE-Salem NJ-Gloucester NJ-Montgomery PA-Bucks PA-
Chester PA-Philadelphia PA-Delaware PA-
553 PM EDT Thu Aug 20 2026

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 615 PM EDT
FOR NORTHERN NEW CASTLE...NORTHWESTERN SALEM...NORTHWESTERN
GLOUCESTER...MONTGOMERY...SOUTHWESTERN BUCKS...EASTERN CHESTER...
PHILADELPHIA AND DELAWARE COUNTIES...

At 553 PM EDT, severe thunderstorms were located along a line
extending from near Green Lane to near Nether Providence Township to
Delaware Memorial Bridge, moving east at 45 mph.

HAZARD...70 mph wind gusts.

SOURCE...Trained weather spotters.

IMPACT...Expect considerable tree damage. Damage is likely to mobile 
         homes, roofs, and outbuildings.

Locations impacted include...
Philadelphia, Camden, Wilmington, Newark, West Chester, Gloucester
City, Norristown, Chester, Pottstown, West Deptford, Phoenixville,
Lansdale, West Norriton, East Norriton, and Pennsville.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Tornado Watch remains in effect until 1000 PM EDT for northern
Delaware...southern New Jersey...and southeastern Pennsylvania.

Remain alert for a possible tornado! Tornadoes can develop quickly
from severe thunderstorms. If you spot a tornado go at once into the
basement or small central room in a sturdy structure.

For your protection move to an interior room on the lowest floor of a
building.

&&

LAT...LON 3993 7570 4028 7562 4031 7554 4032 7513
      3997 7510 3995 7514 3988 7513 3967 7524
      3965 7579
TIME...MOT...LOC 2153Z 267DEG 39KT 4036 7541 3992 7540 3970 7552 

TORNADO...POSSIBLE
THUNDERSTORM DAMAGE THREAT...CONSIDERABLE
HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...<.75 IN
WIND THREAT...OBSERVED
MAX WIND GUST...70 MPH

$$

DeSilva

The office that day

Everything else NWS Philadelphia/Mount Holly issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Aug 20, 4:50 PM EDT	Severe Thunderstorm Warning Considerable damage threat	PHI	Berks, Chester	40 min
Aug 20, 4:59 PM EDT	Severe Thunderstorm Warning Destructive damage threat	PHI	Chester	46 min
Aug 20, 5:22 PM EDT	Tornado Warning	PHI	Chester, Delaware	38 min
Aug 20, 5:39 PM EDT	Flash Flood Warning	PHI	Chester, Delaware, Montgomery, Philadelphia	4 hr
Aug 20, 6:13 PM EDT	Severe Thunderstorm Warning	PHI	Bucks, Delaware, Montgomery, Philadelphia	47 min
Aug 20, 6:26 PM EDT	Flash Flood Warning	PHI	Bucks, Montgomery, Philadelphia	4 hr
Aug 20, 4:16 PM EDT	Tornado Warning	PHI	Kent	29 min
Aug 20, 5:39 PM EDT	Tornado Warning	PHI	Kent	36 min
Aug 20, 5:40 PM EDT	Severe Thunderstorm Warning	PHI	Kent	50 min
Aug 20, 6:03 PM EDT	Tornado Warning	PHI	Kent	42 min
Aug 20, 6:09 PM EDT	Severe Thunderstorm Warning	PHI	Kent, New Castle	51 min
Aug 20, 6:21 PM EDT	Severe Thunderstorm Warning	PHI	Kent, Sussex	39 min
Aug 20, 6:53 PM EDT	Flash Flood Warning Considerable damage threat	PHI	Kent	105 min
Aug 20, 6:57 PM EDT	Severe Thunderstorm Warning	PHI	Kent, Sussex	48 min
Aug 20, 2:04 PM EDT	Special Marine Warning	PHI		86 min
Aug 20, 3:26 PM EDT	Special Marine Warning	PHI		94 min
Aug 20, 4:38 PM EDT	Tornado Warning	PHI	Atlantic	37 min
Aug 20, 4:41 PM EDT	Flash Flood Warning	PHI	Atlantic, Cape May, Cumberland	4 hr
Aug 20, 5:13 PM EDT	Special Marine Warning	PHI		92 min
Aug 20, 5:14 PM EDT	Special Marine Warning	PHI		91 min
Aug 20, 5:24 PM EDT	Flash Flood Warning	PHI	Atlantic	4 hr
Aug 20, 5:36 PM EDT	Special Marine Warning	PHI		84 min
Aug 20, 6:15 PM EDT	Special Marine Warning	PHI		60 min
Aug 20, 6:30 PM EDT	Special Marine Warning	PHI		90 min
Aug 20, 6:38 PM EDT	Severe Thunderstorm Warning	PHI	Atlantic, Cape May, Cumberland	37 min
Aug 20, 6:44 PM EDT	Special Marine Warning	PHI		61 min
Aug 20, 7:01 PM EDT	Tornado Warning	PHI	Atlantic, Cape May, Cumberland	29 min
Aug 20, 7:08 PM EDT	Tornado Warning Tornado observed	PHI	Cape May	22 min
Aug 20, 7:10 PM EDT	Severe Thunderstorm Warning	PHI	Atlantic, Cape May, Cumberland	50 min
Aug 20, 7:37 PM EDT	Special Marine Warning	PHI		2 hr
Aug 20, 7:43 PM EDT	Special Marine Warning	PHI		2 hr

Nearby

Severe Thunderstorm Warnings in Pennsylvania, 2026 Severe Thunderstorm Warnings in New Jersey, 2026 Severe Thunderstorm Warnings in Delaware, 2026 Every 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; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.