Alert archive / Pennsylvania / Severe Thunderstorm Warnings in 2026
Severe Thunderstorm Warning 189, NWS Philadelphia/Mount Holly
NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Jul 18, 2026, 3:45 PM EDT for Chester County, Pennsylvania. It was in force for 45 min. 1 report 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
- Jul 18, 2026, 3:45 PM EDT (19:45 UTC)
- Expired
- Jul 18, 2026, 4:30 PM EDT
- In force
- 45 min
- Issued by
- NWS Philadelphia/Mount Holly
- Area
- Storm-based polygon
- Hail
- 0.75 in
- Wind
- 60.0 mph
County Chester County, PA
The radar
The Dover AFB radar (KDOX), 126 km from the middle of the area, began a volume at 19:47 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 |
|---|---|---|---|
| Jul 18, 3:48 PM EDT | TSTM WND DMG | 2 S Atglen, PA | Tree down at Moccasin Run Golf Club. Time estimated from radar. |
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 |
|---|---|---|---|
| Jul 18, 1:55 PM EDT | Tornado Watch | SPC | 6 hr |
The nearest sounding before it
Washington/Dulle, VA (KIAD), launched 12:00Z, 7.8 hours before the alert went out and 162 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
- 1396 J/kg
- Mixed-layer CIN
- -112 J/kg
- Mixed-layer LCL
- 936 m above ground
- 0-6 km bulk shear
- 31 kt
- 0-1 km storm-relative helicity
- 126 m²/s²
- 0-3 km storm-relative helicity
- 131 m²/s²
- Significant tornado parameter
- 0.4
- Supercell composite
- 5.1
The text
As transmitted.
058
WUUS51 KPHI 181945
SVRPHI
PAC029-182030-
/O.NEW.KPHI.SV.W.0189.260718T1945Z-260718T2030Z/
BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Mount Holly NJ
345 PM EDT Sat Jul 18 2026
The National Weather Service in Mount Holly NJ has issued a
* Severe Thunderstorm Warning for...
Southwestern Chester County in southeastern Pennsylvania...
* Until 430 PM EDT.
* At 345 PM EDT, a severe thunderstorm was located near Homeville, or
14 miles south of New Holland, moving east at 25 mph.
HAZARD...60 mph wind gusts.
SOURCE...Radar indicated.
IMPACT...Damage to roofs, siding, trees, and power lines is
possible.
* Locations impacted include...
Coatesville, Downingtown, Kennett Square, Oxford, Parkesburg, West
Grove, Homeville, Cochranville, Mount Vernon, Marshallton,
Lionville-Marchwood, Atglen, South Coatesville, Avondale, Modena,
Thorndale, Toughkenamon, and Exton.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
A Tornado Watch remains in effect until 900 PM EDT for southeastern
Pennsylvania.
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.
A Tornado Watch remains in effect until 900 PM EDT for southeastern
Pennsylvania.
&&
LAT...LON 3981 7603 3983 7604 3983 7602 3987 7601
3987 7599 3992 7600 3994 7598 3995 7600
4000 7596 4005 7563 3980 7571 3979 7604
TIME...MOT...LOC 1945Z 264DEG 23KT 3990 7601
HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...<.75 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH
$$
MPS2 follow-up statements
744
WWUS51 KPHI 182010
SVSPHI
Severe Weather Statement
National Weather Service Mount Holly NJ
410 PM EDT Sat Jul 18 2026
PAC029-182030-
/O.CON.KPHI.SV.W.0189.000000T0000Z-260718T2030Z/
Chester PA-
410 PM EDT Sat Jul 18 2026
...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 430 PM EDT
FOR SOUTH CENTRAL CHESTER COUNTY...
At 409 PM EDT, a severe thunderstorm was located near Kennett Square,
or 10 miles southwest of West Chester, moving east at 30 mph.
HAZARD...60 mph wind gusts.
SOURCE...Radar indicated.
IMPACT...Damage to roofs, siding, trees, and power lines is
possible.
Locations impacted include...
Coatesville, Kennett Square, West Grove, Marshallton, South
Coatesville, Avondale, Modena, and Toughkenamon.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
A Tornado Watch remains in effect until 900 PM EDT for southeastern
Pennsylvania.
For your protection move to an interior room on the lowest floor of a
building.
To report severe weather contact your nearest law enforcement agency.
They will send your report to the National Weather Service office in
Mount Holly NJ.
&&
LAT...LON 3979 7589 3998 7585 3997 7566 3980 7571
TIME...MOT...LOC 2009Z 280DEG 25KT 3988 7578
HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...<.75 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH
$$
MPS076 WWUS51 KPHI 182020 SVSPHI Severe Weather Statement National Weather Service Mount Holly NJ 420 PM EDT Sat Jul 18 2026 PAC029-182030- /O.EXP.KPHI.SV.W.0189.000000T0000Z-260718T2030Z/ Chester PA- 420 PM EDT Sat Jul 18 2026 ...THE SEVERE THUNDERSTORM WARNING FOR SOUTH CENTRAL CHESTER COUNTY WILL EXPIRE AT 430 PM EDT... The storm which prompted the warning has weakened below severe limits, and has exited the warned area. Therefore, the warning will be allowed to expire. A Tornado 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 3979 7589 3998 7585 3997 7566 3980 7571 TIME...MOT...LOC 2020Z 264DEG 23KT 3989 7572 $$ MPS
The office that day
Everything else NWS Philadelphia/Mount Holly issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jul 18, 10:39 AM EDT | Severe Thunderstorm Warning | PHI | Monroe, Northampton | 21 min |
| Jul 18, 2:44 PM EDT | Flash Flood Warning | PHI | Bucks, Montgomery | 4 hr |
| Jul 18, 3:13 PM EDT | Severe Thunderstorm Warning | PHI | Bucks | 47 min |
| Jul 18, 3:14 PM EDT | Flash Flood Warning | PHI | Bucks | 4 hr |
| Jul 18, 5:45 PM EDT | Severe Thunderstorm Warning | PHI | Bucks, Chester, Delaware, Montgomery, Philadelphia | 45 min |
Nearby
Severe Thunderstorm Warnings in Pennsylvania, 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; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.