Alert archive / Pennsylvania / Severe Thunderstorm Warnings in 2024
Severe Thunderstorm Warning 202, NWS Philadelphia/Mount Holly
NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Aug 18, 2024, 3:34 PM EDT for 4 counties in Pennsylvania. It was in force for 41 min. 8 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, 2024, 3:34 PM EDT (19:34 UTC)
- Expired
- Aug 18, 2024, 4:15 PM EDT
- In force
- 41 min
- Issued by
- NWS Philadelphia/Mount Holly
- Area
- Storm-based polygon
- Hail
- 0.75 in
- Wind
- 60.0 mph
Counties Chester County, PA, Delaware County, PA, Montgomery County, PA, Philadelphia County, PA
The radar
The Philadelphia radar (KDIX), 86 km from the middle of the area, began a volume at 19:37 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, 3:50 PM EDT | HAIL 0.75 | 1 Wnw Chesterbrook, PA | |
| Aug 18, 3:50 PM EDT | HAIL 0.75 | Oaks, PA | Report from mPING: Dime (0.75 in.). |
| Aug 18, 3:52 PM EDT | HAIL 0.75 | 1 Se Oaks, PA | Report from mPING: Dime (0.75 in.). |
| Aug 18, 3:54 PM EDT | HAIL 0.88 | Lower Providence Townsh, PA | |
| Aug 18, 3:59 PM EDT | HAIL 0.88 | Collegeville, PA | |
| Aug 18, 4:03 PM EDT | HAIL 0.88 | 1 Nw Eagleville, PA | |
| Aug 18, 4:06 PM EDT | HAIL 1 | Skippack, PA | |
| Aug 18, 4:07 PM EDT | HAIL 0.5 | 1 N Skippack, PA | Report from mPING: Half-inch (0.50 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 18, 2:02 PM EDT | Severe Thunderstorm Watch | SPC | 8 hr |
The nearest sounding before it
Washington/Dulle, VA (KIAD), launched 12:00Z, 7.6 hours before the alert went out and 210 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
- 821 J/kg
- Mixed-layer CIN
- -68 J/kg
- Mixed-layer LCL
- 623 m above ground
- 0-6 km bulk shear
- 28 kt
- 0-1 km storm-relative helicity
- 28 m²/s²
- 0-3 km storm-relative helicity
- 88 m²/s²
- Significant tornado parameter
- 0.1
- Supercell composite
- 0.4
The text
As transmitted.
087
WUUS51 KPHI 181934
SVRPHI
PAC029-045-091-101-182015-
/O.NEW.KPHI.SV.W.0202.240818T1934Z-240818T2015Z/
BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Mount Holly NJ
334 PM EDT Sun Aug 18 2024
The National Weather Service in Mount Holly NJ has issued a
* Severe Thunderstorm Warning for...
Central Montgomery County in southeastern Pennsylvania...
Northeastern Chester County in southeastern Pennsylvania...
Northwestern Philadelphia County in southeastern Pennsylvania...
North central Delaware County in southeastern Pennsylvania...
* Until 415 PM EDT.
* At 334 PM EDT, a severe thunderstorm was located over Paoli, or 7
miles northeast of West Chester, moving northeast 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...
Philadelphia, Norristown, Phoenixville, Lansdale, West Norriton,
East Norriton, Conshohocken, Ambler, Collegeville, Trappe, Willow
Grove, Bryn Mawr, Trout Lake, Radnor Township, Gradyville, Valley
Forge, Plymouth Meeting, Paoli, Newtown Square, and King Of
Prussia.
This includes the following highways...
Pennsylvania Turnpike between mile markers 317 and 342.
Northeast Extension between mile markers 21 and 33.
Interstate 76 in Pennsylvania between mile markers 327 and 335.
Interstate 476 in Pennsylvania between mile markers 11 and 19.
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 3992 7547 4000 7564 4031 7539 4015 7510
TIME...MOT...LOC 1934Z 219DEG 21KT 4001 7549
HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...0.75 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH
$$
MPS3 follow-up statements
178
WWUS51 KPHI 181941
SVSPHI
Severe Weather Statement
National Weather Service Mount Holly NJ
341 PM EDT Sun Aug 18 2024
PAC101-181951-
/O.CAN.KPHI.SV.W.0202.000000T0000Z-240818T2015Z/
Philadelphia PA-
341 PM EDT Sun Aug 18 2024
...THE SEVERE THUNDERSTORM WARNING FOR NORTHWESTERN PHILADELPHIA
COUNTY IS CANCELLED...
The severe thunderstorm which prompted the warning has moved out of
the warned area. Therefore, the warning has been cancelled.
A Severe Thunderstorm Watch remains in effect until 1000 PM EDT for
southeastern Pennsylvania.
LAT...LON 3997 7544 4003 7558 4013 7553 4031 7539
4020 7518
TIME...MOT...LOC 1941Z 210DEG 21KT 4007 7547
$$
PAC029-045-091-182015-
/O.CON.KPHI.SV.W.0202.000000T0000Z-240818T2015Z/
Montgomery PA-Chester PA-Delaware PA-
341 PM EDT Sun Aug 18 2024
...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 415 PM EDT
FOR CENTRAL MONTGOMERY...NORTHEASTERN CHESTER AND NORTH CENTRAL
DELAWARE COUNTIES...
At 341 PM EDT, a severe thunderstorm was located over Valley Forge,
or 10 miles northeast of West Chester, moving northeast at 25 mph.
HAZARD...60 mph wind gusts and half dollar size hail.
SOURCE...Radar indicated.
IMPACT...Minor damage to vehicles is possible. Wind damage to roofs,
siding, trees, and power lines is possible.
Locations impacted include...
Norristown, Phoenixville, Lansdale, West Norriton, East Norriton,
Ambler, Collegeville, Trappe, Valley Forge, Paoli, King Of Prussia,
Plymouth Meeting, Radnor Township, Skippack, Bridgeport, North Wales,
Malvern, West Conshohocken, Harleysville, and Evansburg.
This includes the following highways...
Pennsylvania Turnpike between mile markers 319 and 333.
Northeast Extension between mile markers 21 and 33.
Interstate 76 in Pennsylvania between mile markers 327 and 330.
Interstate 476 in Pennsylvania near mile marker 18.
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 3997 7544 4003 7558 4013 7553 4031 7539
4020 7518
TIME...MOT...LOC 1941Z 210DEG 21KT 4007 7547
HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...1.25 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH
$$
MPS956
WWUS51 KPHI 181951
SVSPHI
Severe Weather Statement
National Weather Service Mount Holly NJ
351 PM EDT Sun Aug 18 2024
PAC029-045-182001-
/O.CAN.KPHI.SV.W.0202.000000T0000Z-240818T2015Z/
Chester PA-Delaware PA-
351 PM EDT Sun Aug 18 2024
...THE SEVERE THUNDERSTORM WARNING FOR NORTHEASTERN CHESTER AND NORTH
CENTRAL DELAWARE COUNTIES IS CANCELLED...
The severe thunderstorm which prompted the warning has moved out of
the warned area. Therefore, the warning has been cancelled.
A Severe Thunderstorm Watch remains in effect until 1000 PM EDT for
southeastern Pennsylvania.
LAT...LON 4016 7550 4031 7539 4022 7522 4007 7536
4006 7539 4009 7542 4009 7544 4011 7547
4013 7546 4013 7550 4014 7551
TIME...MOT...LOC 1951Z 203DEG 21KT 4014 7545
$$
PAC091-182015-
/O.CON.KPHI.SV.W.0202.000000T0000Z-240818T2015Z/
Montgomery PA-
351 PM EDT Sun Aug 18 2024
...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 415 PM EDT
FOR CENTRAL MONTGOMERY COUNTY...
At 351 PM EDT, a severe thunderstorm was located near Valley Forge,
or 14 miles northeast of West Chester, moving northeast at 25 mph.
HAZARD...60 mph wind gusts and half dollar size hail.
SOURCE...Radar indicated.
IMPACT...Minor damage to vehicles is possible. Wind damage to roofs,
siding, trees, and power lines is possible.
Locations impacted include...
Norristown, Phoenixville, Lansdale, West Norriton, East Norriton,
Collegeville, Trappe, King Of Prussia, Skippack, Bridgeport, North
Wales, Harleysville, Evansburg, Audubon, Eagleville, Trooper,
Kulpsville, Blue Bell, and Montgomeryville.
This includes the following highways...
Pennsylvania Turnpike between mile markers 326 and 330.
Northeast Extension between mile markers 23 and 33.
Interstate 76 in Pennsylvania between mile markers 327 and 329.
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 4016 7550 4031 7539 4022 7522 4007 7536
4006 7539 4009 7542 4009 7544 4011 7547
4013 7546 4013 7550 4014 7551
TIME...MOT...LOC 1951Z 203DEG 21KT 4014 7545
HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...1.25 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH
$$
MPS955
WWUS51 KPHI 182005
SVSPHI
Severe Weather Statement
National Weather Service Mount Holly NJ
405 PM EDT Sun Aug 18 2024
PAC091-182015-
/O.EXP.KPHI.SV.W.0202.000000T0000Z-240818T2015Z/
Montgomery PA-
405 PM EDT Sun Aug 18 2024
...THE SEVERE THUNDERSTORM WARNING FOR CENTRAL MONTGOMERY COUNTY WILL
EXPIRE AT 415 PM EDT...
The storm which prompted the warning has weakened below severe
limits, and no longer poses an immediate threat to life or property.
Therefore, the warning will be allowed to expire. However heavy rain
is still possible with this thunderstorm.
A Severe Thunderstorm Watch remains in effect until 1000 PM EDT for
southeastern Pennsylvania.
To report severe weather, contact your nearest law enforcement
agency. They will relay your report to the National Weather Service
Mount Holly NJ.
LAT...LON 4016 7550 4031 7539 4022 7522 4007 7536
4006 7539 4009 7542 4009 7544 4011 7547
4013 7546 4013 7550 4014 7551
TIME...MOT...LOC 2005Z 219DEG 21KT 4020 7539
$$
MPSThe office that day
Everything else NWS Philadelphia/Mount Holly issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 18, 1:35 AM EDT | Flash Flood Warning | PHI | Bucks, Delaware, Montgomery, Philadelphia | 2 hr |
| Aug 18, 3:09 AM EDT | Flash Flood Warning | PHI | Bucks | 93 min |
| Aug 18, 3:24 PM EDT | Severe Thunderstorm Warning | PHI | Monroe, Northampton | 19 min |
| Aug 18, 3:48 PM EDT | Severe Thunderstorm Warning | PHI | Carbon, Monroe | 42 min |
| Aug 18, 4:04 PM EDT | Severe Thunderstorm Warning | PHI | Monroe | 41 min |
| Aug 18, 4:25 PM EDT | Severe Thunderstorm Warning | PHI | Bucks, Lehigh, Montgomery, Northampton | 28 min |
| Aug 18, 4:41 PM EDT | Severe Thunderstorm Warning | PHI | Monroe, Northampton | 34 min |
| Aug 18, 4:56 PM EDT | Flash Flood Warning | PHI | Monroe, Northampton | 6 hr |
| Aug 18, 5:21 PM EDT | Severe Thunderstorm Warning | PHI | Bucks | 39 min |
| Aug 18, 5:31 PM EDT | Flash Flood Warning | PHI | Bucks, Lehigh, Northampton | 6 hr |
| Aug 18, 5:47 PM EDT | Severe Thunderstorm Warning | PHI | Bucks | 58 min |
Nearby
Severe Thunderstorm Warnings in Pennsylvania, 2024Every severe thunderstorm warning in 2024
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.