Alert archive / Pennsylvania / Severe Thunderstorm Warnings in 2024

Severe Thunderstorm Warning 145, NWS Philadelphia/Mount Holly

July 17, 2024Berks County, Chester County, Montgomery County, Pennsylvania

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Jul 17, 2024, 2:16 PM EDT for Berks County, Chester County, Montgomery County, Pennsylvania. It was in force for 59 min. 10 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
Jul 17, 2024, 2:16 PM EDT (18:16 UTC)
Expired
Jul 17, 2024, 3:15 PM EDT
In force
59 min
Issued by
NWS Philadelphia/Mount Holly
Area
Storm-based polygon
Hail
1.0 in
Wind
60.0 mph

Counties Berks County, PA, Chester County, PA, Montgomery County, PA

The radar

The Philadelphia radar (KDIX), 120 km from the middle of the area, began a volume at 18:17 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

TimeReportWhereRemark
Jul 17, 2:42 PM EDTTSTM WND DMG1 Ene East Brandywine T, PAPhotos of large limbs and a few trees down near Corner Ketch Rd and Rolling Glenn Lane. Time estimated.
Jul 17, 2:49 PM EDTTSTM WND DMGExton, PASeveral photos of many large tree limbs and a few trees snapped in Exton. Time estimated.
Jul 17, 2:52 PM EDTTSTM WND GST 671 Nne East Caln Twp, PATrained spotter measures wind gust of 66.8 mph on a mounted ATMOS 41 research weather station. Also reports of powerlines and poles down along Creekside Dr.
Jul 17, 2:54 PM EDTTSTM WND GST 482 Wsw Upper Uwchlan Twp, PAMarsh Creek - XMAR WxFlow Site.
Jul 17, 2:55 PM EDTTSTM WND GST 461 Nnw West Goshen, PAAWOS station KOQN West Chester.
Jul 17, 2:59 PM EDTTSTM WND DMGChester Springs, PAMultiple reports of large trees down all around Chester Springs area. Time estimated from radar.
Jul 17, 3:00 PM EDTTSTM WND DMGMalvern, PATrees and wires down. Time estimated from radar.
Jul 17, 3:01 PM EDTTSTM WND GST 712 Se Exton, PALast physical read via physical anemometer was 71 mph, however, shut off before the peak wind. Severe winds lasted for 4 minutes and 30 seconds. Significant uprooting of trees, damage to house, telephone electric pole uprooted on Kirkland Avenue. Photos show a
Jul 17, 3:11 PM EDTTSTM WND DMG1 Wnw Chesterbrook, PAReceived photos of a large tree that fell down on backyard deck with multiple other trees down on roads. Time estimated.
Jul 17, 3:14 PM EDTTSTM WND DMG1 Ne Valley Forge, PADelayed report from last week. NWS employee relayed photos of several large trees uprooted and snapped on a trail in Valley Forge National Historical Park. Other tree damage in the area as well. Time estimated.

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.

IssuedProductOfficeLasted
Jul 17, 12:58 PM EDTSevere Thunderstorm WatchSPC10 hr

The nearest sounding before it

Washington/Dulle, VA (KIAD), launched 12:00Z, 6.3 hours before the alert went out and 185 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-pSkew-T log-p diagram, Washington/Dulle, VA at 12:00Z on 2024-07-17Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 88 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Washington/Dulle, VA at 12:00Z on 2024-07-17The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -22 square meters per square second.1939Sfc1 km3 km6 km9 kmRMLM
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
88 J/kg
Mixed-layer CIN
-120 J/kg
Mixed-layer LCL
1518 m above ground
0-6 km bulk shear
28 kt
0-1 km storm-relative helicity
-22 m²/s²
0-3 km storm-relative helicity
96 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.1

Open this sounding in Storm Lab

The text

As transmitted.

816 
WUUS51 KPHI 171816
SVRPHI
PAC011-029-091-171915-
/O.NEW.KPHI.SV.W.0145.240717T1816Z-240717T1915Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Mount Holly NJ
216 PM EDT Wed Jul 17 2024

The National Weather Service in Mount Holly NJ has issued a

* Severe Thunderstorm Warning for...
  Southeastern Berks County in eastern Pennsylvania...
  Northwestern Montgomery County in southeastern Pennsylvania...
  Chester County in southeastern Pennsylvania...

* Until 315 PM EDT.

* At 215 PM EDT, severe thunderstorms were located along a line
  extending from near Terre Hill to near New Holland to near Gap,
  moving east at 30 mph.

  HAZARD...60 mph wind gusts and quarter 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...
  West Chester, Pottstown, Phoenixville, Coatesville, Downingtown,
  Birdsboro, Collegeville, Royersford, Parkesburg, Trappe, Honey
  Brook, Schwenksville, Elverson, Green Lane, New Morgan,
  Cochranville, Pughtown, Marshallton, Spring Mount, and
  Lionville-Marchwood.

This includes the following highways...
 Pennsylvania Turnpike between mile markers 296 and 323.
 Interstate 176 in Pennsylvania between mile markers 1 and 8.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

In addition to large hail and damaging winds, frequent cloud to
ground lightning is occurring with these storms. Move indoors
immediately. Remember, if you can hear thunder, you are close enough
to be struck by lightning.

&&

LAT...LON 4036 7547 4011 7544 3988 7559 3989 7599
      3992 7600 3994 7598 3995 7600 4004 7593
      4011 7594 4014 7588 4024 7603
TIME...MOT...LOC 1815Z 261DEG 26KT 4014 7602 4006 7602 3997 7607 

HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...1.00 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH

$$

Staarmann
3 follow-up statements
343 
WWUS51 KPHI 171832
SVSPHI

Severe Weather Statement
National Weather Service Mount Holly NJ
232 PM EDT Wed Jul 17 2024

PAC011-029-091-171915-
/O.CON.KPHI.SV.W.0145.000000T0000Z-240717T1915Z/
Berks PA-Montgomery PA-Chester PA-
232 PM EDT Wed Jul 17 2024

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 315 PM EDT
FOR SOUTHEASTERN BERKS...NORTHWESTERN MONTGOMERY AND CHESTER
COUNTIES...

At 232 PM EDT, severe thunderstorms were located along a line
extending from Elverson to near Honey Brook to Parkesburg, moving
east at 30 mph.

HAZARD...60 mph wind gusts and quarter 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...
West Chester, Pottstown, Phoenixville, Coatesville, Downingtown,
Birdsboro, Collegeville, Royersford, Parkesburg, Trappe, Honey Brook,
Schwenksville, Elverson, Green Lane, New Morgan, Cochranville,
Pughtown, Marshallton, Spring Mount, and Lionville-Marchwood.

This includes the following highways...
 Pennsylvania Turnpike between mile markers 296 and 323.
 Interstate 176 in Pennsylvania between mile markers 1 and 8.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Frequent cloud to ground lightning is occurring with these storms.
Move indoors immediately. Lightning is one of nature's leading
killers. Remember, if you can hear thunder, you are close enough to
be struck by lightning.

&&

LAT...LON 4036 7547 4011 7544 3988 7559 3989 7599
      3992 7600 3994 7598 3995 7600 4004 7593
      4011 7594 4014 7588 4024 7603
TIME...MOT...LOC 1832Z 260DEG 27KT 4017 7585 4008 7584 3997 7591 

HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...1.00 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH

$$

Staarmann
975 
WWUS51 KPHI 171848
SVSPHI

Severe Weather Statement
National Weather Service Mount Holly NJ
248 PM EDT Wed Jul 17 2024

PAC011-171857-
/O.CAN.KPHI.SV.W.0145.000000T0000Z-240717T1915Z/
Berks PA-
248 PM EDT Wed Jul 17 2024

...THE SEVERE THUNDERSTORM WARNING FOR SOUTHEASTERN BERKS 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 800 PM EDT for
eastern and southeastern Pennsylvania.

LAT...LON 4004 7593 4011 7594 4014 7587 4023 7571
      4033 7563 4036 7547 4011 7544 3988 7559
      3989 7599 3992 7600 3994 7598 3995 7600
TIME...MOT...LOC 1847Z 264DEG 26KT 4004 7570 

$$

PAC029-091-171915-
/O.CON.KPHI.SV.W.0145.000000T0000Z-240717T1915Z/
Montgomery PA-Chester PA-
248 PM EDT Wed Jul 17 2024

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 315 PM EDT
FOR NORTHWESTERN MONTGOMERY AND CHESTER COUNTIES...

At 247 PM EDT, a severe thunderstorm was located over Downingtown, or
7 miles northwest of West Chester, moving east at 30 mph.

HAZARD...60 mph wind gusts and quarter 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...
West Chester, Pottstown, Phoenixville, Coatesville, Downingtown,
Collegeville, Royersford, Parkesburg, Trappe, Honey Brook,
Schwenksville, Elverson, Green Lane, Cochranville, Pughtown,
Marshallton, Spring Mount, Lionville-Marchwood, Valley Forge, and
Glenmoore.

This includes Pennsylvania Turnpike between mile markers 301 and 323.
 
PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Frequent cloud to ground lightning is occurring with this storm. Move
indoors immediately. Lightning is one of nature's leading killers.
Remember, if you can hear thunder, you are close enough to be struck
by lightning.

Torrential rainfall is occurring with this storm, and may lead to
flash flooding. Do not drive your vehicle through flooded roadways.

&&

LAT...LON 4004 7593 4011 7594 4014 7587 4023 7571
      4033 7563 4036 7547 4011 7544 3988 7559
      3989 7599 3992 7600 3994 7598 3995 7600
TIME...MOT...LOC 1847Z 264DEG 26KT 4004 7570 

HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...1.00 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH

$$

Staarmann
524 
WWUS51 KPHI 171903
SVSPHI

Severe Weather Statement
National Weather Service Mount Holly NJ
303 PM EDT Wed Jul 17 2024

PAC029-091-171915-
/O.CON.KPHI.SV.W.0145.000000T0000Z-240717T1915Z/
Montgomery PA-Chester PA-
303 PM EDT Wed Jul 17 2024

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 315 PM EDT
FOR WEST CENTRAL MONTGOMERY AND CENTRAL CHESTER COUNTIES...

At 303 PM EDT, a severe thunderstorm was located near Chester
Springs, or 8 miles north of West Chester, moving east at 35 mph.

HAZARD...60 mph wind gusts and quarter 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...
West Chester, Pottstown, Phoenixville, Coatesville, Downingtown,
Collegeville, Royersford, Trappe, Schwenksville, Pughtown,
Marshallton, Spring Mount, Lionville-Marchwood, Valley Forge,
Glenmoore, Paoli, Chester Springs, Lionville, Cedarville, and West
Goshen.

This includes Pennsylvania Turnpike between mile markers 302 and 323.
 
PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Frequent cloud to ground lightning is occurring with this storm. Move
indoors immediately. Lightning is one of nature's leading killers.
Remember, if you can hear thunder, you are close enough to be struck
by lightning.

Torrential rainfall is occurring with this storm, and may lead to
flash flooding. Do not drive your vehicle through flooded roadways.

&&

LAT...LON 4004 7587 4017 7581 4023 7571 4026 7562
      4030 7546 4011 7544 3988 7559 3989 7587
TIME...MOT...LOC 1903Z 264DEG 30KT 4007 7556 

HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...1.00 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH

$$

Staarmann

The office that day

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

IssuedProductOfficeCountiesLasted
Jul 16, 8:05 PM EDTSevere Thunderstorm WarningPHIChester, Delaware70 min
Jul 16, 8:13 PM EDTSevere Thunderstorm WarningPHIBucks, Montgomery62 min
Jul 16, 8:23 PM EDTSevere Thunderstorm WarningPHIBucks, Delaware, Montgomery, Philadelphia67 min
Jul 16, 9:04 PM EDTSevere Thunderstorm WarningPHIDelaware56 min
Jul 17, 3:05 PM EDTSevere Thunderstorm WarningPHIBucks, Chester, Delaware, Montgomery, Philadelphia39 min
Jul 17, 5:51 PM EDTSevere Thunderstorm WarningPHICarbon, Monroe54 min
Jul 17, 6:18 PM EDTSevere Thunderstorm WarningPHICarbon, Lehigh, Monroe57 min
Jul 17, 6:40 PM EDTSevere Thunderstorm WarningPHIMonroe, Northampton65 min
Jul 17, 7:06 PM EDTSevere Thunderstorm WarningPHIBerks, Bucks, Chester, Lehigh, Montgomery, Northampton54 min
Jul 17, 7:18 PM EDTFlash Flood WarningPHICarbon, Lehigh, Monroe, Northampton2 hr

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.