Alert archive / Pennsylvania / Severe Thunderstorm Warnings in 2019

Severe Thunderstorm Warning 375, NWS Philadelphia/Mount Holly

August 21, 2019Berks County, Chester County, Montgomery County, Pennsylvania

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Aug 21, 2019, 3:08 PM EDT for Berks County, Chester County, Montgomery County, Pennsylvania. It was in force for 34 min. 4 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 21, 2019, 3:08 PM EDT (19:08 UTC)
Expired
Aug 21, 2019, 3:42 PM EDT
In force
34 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), 113 km from the middle of the area, began a volume at 19:10 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
Aug 21, 3:08 PM EDTTSTM WND DMG1 Sw Robeson Twp, PASEVERAL REPORTS OF TREES, POWER LINES, AND POWER POLES DOWN AROUND PLOW ROAD IN ROBESON TWP. TIME ESTIMATED FROM RADAR.
Aug 21, 3:14 PM EDTTSTM WND DMG1 E Lorane, PATREE DOWN NEAR LINCOLN ROAD AND LORANE ROAD. TIME ESTIMATED FROM RADAR.
Aug 21, 3:14 PM EDTTSTM WND DMG2 Sse Robeson Twp, PATREE DOWN ON WIRES ON HAYCREEK ROAD. TIME ESTIMATED FROM RADAR.
Aug 21, 3:33 PM EDTTSTM WND DMG1 S Douglassville, PADOWNED TREE AND WIRES NEAR THE INTERSECTION OF BLACK MATT ROAD AND YOCUM ROAD. TIME ESTIMATED FROM RADAR.

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

The nearest sounding before it

Washington/Dulle, VA (KIAD), launched 12:00Z, 7.1 hours before the alert went out and 215 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 2019-08-21Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 190 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 2019-08-21The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 51 square meters per square second.193958Sfc1 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
190 J/kg
Mixed-layer CIN
-216 J/kg
Mixed-layer LCL
1166 m above ground
0-6 km bulk shear
22 kt
0-1 km storm-relative helicity
51 m²/s²
0-3 km storm-relative helicity
27 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

748 
WUUS51 KPHI 211908
SVRPHI
PAC011-029-091-212000-
/O.NEW.KPHI.SV.W.0375.190821T1908Z-190821T2000Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Mount Holly NJ
308 PM EDT Wed Aug 21 2019

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...
  North central Chester County in southeastern Pennsylvania...

* Until 400 PM EDT.

* At 308 PM EDT, a severe thunderstorm was located over Birdsboro, or
  near Reading, moving east at 20 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...
  Reading, Pottstown, Birdsboro, Collegeville, Royersford, Trappe,
  East Greenville, Schwenksville, Bally, Bechtelsville, Green Lane,
  Spring Mount, Gilbertsville, Cedarville, Stowe, Shillington,
  Boyertown, Pennsburg, Spring City and Mount Penn.

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, and
the storm will affect the beaches. For your safety, immediately move
off the beach and seek shelter indoors.

&&

LAT...LON 4044 7552 4041 7547 4016 7541 4021 7596
      4031 7596
TIME...MOT...LOC 1908Z 262DEG 18KT 4025 7586 

HAIL...1.00IN
WIND...60MPH
 
$$

Gorse
2 follow-up statements
430 
WWUS51 KPHI 211922
SVSPHI

Severe Weather Statement
National Weather Service Mount Holly NJ
322 PM EDT Wed Aug 21 2019

PAC011-029-091-212000-
/O.CON.KPHI.SV.W.0375.000000T0000Z-190821T2000Z/
Berks PA-Montgomery PA-Chester PA-
322 PM EDT Wed Aug 21 2019

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 400 PM EDT
FOR SOUTHEASTERN BERKS...NORTHWESTERN MONTGOMERY AND NORTHEASTERN
CHESTER COUNTIES...

At 321 PM EDT, a severe thunderstorm was located near Birdsboro, or
10 miles southeast of Reading, moving east at 20 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...
Pottstown, Birdsboro, Collegeville, Royersford, Trappe, East
Greenville, Schwenksville, Bally, Bechtelsville, Green Lane, Spring
Mount, Gilbertsville, Cedarville, Stowe, Boyertown, Pennsburg, Spring
City, Red Hill, St. Lawrence and Pottsgrove.

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.

&&

LAT...LON 4044 7552 4041 7547 4016 7541 4021 7590
      4032 7590
TIME...MOT...LOC 1921Z 261DEG 19KT 4027 7575 

HAIL...1.00IN
WIND...60MPH
 
$$

Gorse
600 
WWUS51 KPHI 211942
SVSPHI

Severe Weather Statement
National Weather Service Mount Holly NJ
342 PM EDT Wed Aug 21 2019

PAC011-029-091-211952-
/O.CAN.KPHI.SV.W.0375.000000T0000Z-190821T2000Z/
Berks PA-Montgomery PA-Chester PA-
342 PM EDT Wed Aug 21 2019

...THE SEVERE THUNDERSTORM WARNING FOR SOUTHEASTERN BERKS...
NORTHWESTERN MONTGOMERY AND NORTHEASTERN CHESTER 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. However small hail and 
gusty winds are still possible with this thunderstorm.

A severe thunderstorm watch remains in effect until 1000 PM EDT for
eastern and southeastern Pennsylvania.

LAT...LON 4044 7552 4041 7547 4016 7541 4021 7590
      4032 7590
TIME...MOT...LOC 1938Z 262DEG 18KT 4028 7561 

$$

Gorse

The office that day

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

IssuedProductOfficeCountiesLasted
Aug 21, 3:01 PM EDTSpecial Weather StatementPHIBerks29 min
Aug 21, 4:07 PM EDTSevere Thunderstorm WarningPHIChester, Montgomery38 min
Aug 21, 7:58 PM EDTSpecial Weather StatementPHIChester47 min

Nearby

Severe Thunderstorm Warnings in Pennsylvania, 2019Every severe thunderstorm warning in 2019

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.