Alert archive / Pennsylvania / Severe Thunderstorm Warnings in 2018

Severe Thunderstorm Warning 82, NWS Philadelphia/Mount Holly

August 17, 20188 counties in Pennsylvania

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Aug 17, 2018, 7:09 PM EDT for 8 counties in Pennsylvania. It was in force for 51 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 17, 2018, 7:09 PM EDT (23:09 UTC)
Expired
Aug 17, 2018, 8:00 PM EDT
In force
51 min
Issued by
NWS Philadelphia/Mount Holly
Area
Storm-based polygon
Hail
0.75 in
Wind
70.0 mph

Counties Berks County, PA, Bucks County, PA, Carbon County, PA, Chester County, PA, Lehigh County, PA, Monroe County, PA, Montgomery County, PA, Northampton County, PA

The radar

The Philadelphia radar (KDIX), 128 km from the middle of the area, began a volume at 23:12 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 17, 7:12 PM EDTTSTM WND DMGRextown, PATREE DOWN ON EAST GRANT STREET IN WASHINGTON TWP, FORCING THE TEMPORARY CLOSURE OF THE ROAD. TIME ESTIMATED FROM RADAR.
Aug 17, 7:22 PM EDTTSTM WND DMG1 Wnw Hereford, PATREE DOWN AT SEISHOLTZVILLE ROAD AND CHICKADEE LANE.
Aug 17, 7:37 PM EDTTSTM WND DMG1 Sse Kirchberg, PAREPORT OF TREES DOWN IN LOWER SAUCON TWP. TIME ESTIMATED FROM RADAR.
Aug 17, 7:42 PM EDTTSTM WND DMG1 Wnw Brookview, PATREE DOWN AT SAWMILL ROAD AND HAUSEMAN ROAD IN COLEBROOKDALE TWP. 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.

IssuedProductOfficeLasted
Aug 17, 3:44 PM EDTSevere Thunderstorm WatchSPC7 hr

The nearest sounding before it

Washington/Dulle, VA (KIAD), launched 12:00Z, 11.2 hours before the alert went out and 223 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 2018-08-17Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 750 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 2018-08-17The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 80 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
750 J/kg
Mixed-layer CIN
-101 J/kg
Mixed-layer LCL
1186 m above ground
0-6 km bulk shear
16 kt
0-1 km storm-relative helicity
80 m²/s²
0-3 km storm-relative helicity
69 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

701 
WUUS51 KPHI 172309
SVRPHI
PAC011-017-025-029-077-089-091-095-180000-
/O.NEW.KPHI.SV.W.0082.180817T2309Z-180818T0000Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Mount Holly NJ
709 PM EDT FRI AUG 17 2018

The National Weather Service in Mount Holly NJ has issued a

* Severe Thunderstorm Warning for...
  Eastern Berks County in eastern Pennsylvania...
  Northwestern Montgomery County in southeastern Pennsylvania...
  Lehigh County in eastern Pennsylvania...
  Southeastern Carbon County in northeastern Pennsylvania...
  Northwestern Bucks County in southeastern Pennsylvania...
  Northeastern Chester County in southeastern Pennsylvania...
  Southwestern Monroe County in northeastern Pennsylvania...
  Southwestern Northampton County in eastern Pennsylvania...

* Until 800 PM EDT.

* At 708 PM EDT, severe thunderstorms were located along a line
  extending from Lehighton to Jordan Valley to near Fleetwood to
  Terre Hill, moving northeast at 35 mph.

  HAZARD...70 mph wind gusts.

  SOURCE...Radar indicated.

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

* Locations impacted include...
  Allentown, Reading, Lehighton, Bethlehem, Pottstown, Phoenixville,
  Emmaus, Wyomissing, Northampton, Quakertown, Hellertown, Nazareth,
  Palmerton, Birdsboro, Kutztown, Jim Thorpe, Royersford, Slatington,
  Fleetwood and Sinking Spring.

People attending Philadelphia Folk Festival should seek safe shelter
immediately!

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.

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

&&

LAT...LON 4070 7584 4074 7576 4079 7585 4085 7586
      4104 7539 4058 7529 4036 7538 4010 7555
      4009 7594 4011 7594 4014 7588 4025 7605
TIME...MOT...LOC 2308Z 224DEG 31KT 4084 7575 4073 7568 4041 7577 4013
7606

HAIL...<.75IN
WIND...70MPH
 
$$

CMS
3 follow-up statements
884 
WWUS51 KPHI 172327
SVSPHI

Severe Weather Statement
National Weather Service Mount Holly NJ
727 PM EDT FRI AUG 17 2018

PAC011-017-025-029-077-089-091-095-180000-
/O.CON.KPHI.SV.W.0082.000000T0000Z-180818T0000Z/
Berks PA-Montgomery PA-Lehigh PA-Carbon PA-Bucks PA-Chester PA-
Monroe PA-Northampton PA-
727 PM EDT FRI AUG 17 2018

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 800 PM EDT
FOR EASTERN BERKS...NORTHWESTERN MONTGOMERY...LEHIGH...SOUTHEASTERN
CARBON...NORTHWESTERN BUCKS...NORTHEASTERN CHESTER...SOUTHWESTERN
MONROE AND SOUTHWESTERN NORTHAMPTON COUNTIES...

At 726 PM EDT, severe thunderstorms were located along a line
extending from near Christmans to near Danielsville to near Ancient
Oaks to near New Morgan, moving northeast at 35 mph.

HAZARD...60 mph wind gusts.

SOURCE...Public. Several reports of wind damage have been received 
         from Berks County during the past half hour.

IMPACT...Damage to roofs, siding, trees, and power lines is 
         possible.

Locations impacted include...
Allentown, Reading, Lehighton, Bethlehem, Pottstown, Phoenixville,
Emmaus, Wyomissing, Northampton, Quakertown, Hellertown, Nazareth,
Palmerton, Birdsboro, Kutztown, Jim Thorpe, Royersford, Slatington,
Fleetwood and Sinking Spring.

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.

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

&&

LAT...LON 4040 7598 4057 7577 4071 7582 4074 7576
      4079 7585 4085 7586 4104 7539 4058 7529
      4036 7538 4010 7555 4009 7594 4011 7594
      4014 7588 4025 7605
TIME...MOT...LOC 2326Z 224DEG 31KT 4094 7562 4083 7555 4051 7564 4023
7593

HAIL...<.75IN
WIND...60MPH
 
$$

CMS
801 
WWUS51 KPHI 172336
SVSPHI

Severe Weather Statement
National Weather Service Mount Holly NJ
736 PM EDT FRI AUG 17 2018

PAC011-017-025-029-077-089-091-095-180000-
/O.CON.KPHI.SV.W.0082.000000T0000Z-180818T0000Z/
Berks PA-Montgomery PA-Lehigh PA-Carbon PA-Bucks PA-Chester PA-
Monroe PA-Northampton PA-
736 PM EDT FRI AUG 17 2018

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 800 PM EDT
FOR SOUTHEASTERN BERKS...NORTHWESTERN MONTGOMERY...LEHIGH...
SOUTHEASTERN CARBON...NORTHWESTERN BUCKS...NORTHEASTERN CHESTER...
SOUTHWESTERN MONROE AND SOUTHWESTERN NORTHAMPTON COUNTIES...

At 735 PM EDT, severe thunderstorms were located along a line
extending from Meckesville to Kunkletown to near Emmaus to
Cedarville, moving northeast at 40 mph.

HAZARD...60 mph wind gusts.

SOURCE...Public. Several reports of downed trees have been received 
         near Reading during the past half hour.

IMPACT...Damage to roofs, siding, trees, and power lines is 
         possible.

Locations impacted include...
Allentown, Reading, Bethlehem, Pottstown, Phoenixville, Emmaus,
Wyomissing, Northampton, Quakertown, Hellertown, Nazareth, Palmerton,
Birdsboro, Kutztown, Royersford, Slatington, Fleetwood, Sinking
Spring, Laureldale and Trappe.

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.

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

&&

LAT...LON 4040 7598 4055 7570 4078 7559 4094 7563
      4104 7539 4058 7529 4036 7538 4010 7555
      4014 7588 4025 7605
TIME...MOT...LOC 2335Z 238DEG 36KT 4101 7553 4083 7545 4053 7544 4025
7570

HAIL...<.75IN
WIND...60MPH
 
$$

CMS
127 
WWUS51 KPHI 172352
SVSPHI

Severe Weather Statement
National Weather Service Mount Holly NJ
752 PM EDT FRI AUG 17 2018

PAC011-017-025-029-077-089-091-095-180002-
/O.EXP.KPHI.SV.W.0082.000000T0000Z-180818T0000Z/
Berks PA-Montgomery PA-Lehigh PA-Carbon PA-Bucks PA-Chester PA-
Monroe PA-Northampton PA-
752 PM EDT FRI AUG 17 2018

...THE SEVERE THUNDERSTORM WARNING FOR SOUTHEASTERN BERKS...
NORTHWESTERN MONTGOMERY...LEHIGH...SOUTHEASTERN CARBON...NORTHWESTERN
BUCKS...NORTHEASTERN CHESTER...SOUTHWESTERN MONROE AND SOUTHWESTERN
NORTHAMPTON COUNTIES WILL EXPIRE AT 800 PM EDT...
    
The storms which prompted the warning have weakened below severe 
limits, and are exiting the warned area. Therefore, the warning will 
be allowed to expire.  However gusty winds and heavy rain are still 
possible with these thunderstorms.

A severe thunderstorm watch remains in effect until 1100 PM EDT for
eastern and northeastern Pennsylvania.

To report severe weather, contact your nearest law enforcement
agency. They will relay your report to the National Weather Service
in Mount Holly NJ.

LAT...LON 4040 7598 4055 7570 4078 7559 4094 7563
      4104 7539 4058 7529 4036 7538 4010 7555
      4014 7588 4025 7605
TIME...MOT...LOC 2352Z 224DEG 31KT 4110 7541 4092 7533 4062 7532 4034
7558

$$

CMS

The office that day

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

IssuedProductOfficeCountiesLasted
Aug 17, 2:21 PM EDTSpecial Weather StatementPHILehigh24 min
Aug 17, 4:29 PM EDTSpecial Weather StatementPHIBerks46 min
Aug 17, 5:07 PM EDTSpecial Weather StatementPHIBerks, Lehigh53 min
Aug 17, 5:12 PM EDTSpecial Weather StatementPHIBerks33 min
Aug 17, 5:36 PM EDTSpecial Weather StatementPHILehigh, Northampton39 min
Aug 17, 5:59 PM EDTSevere Thunderstorm WarningPHIMonroe, Northampton31 min
Aug 17, 6:00 PM EDTSpecial Weather StatementPHICarbon30 min
Aug 17, 6:18 PM EDTSpecial Weather StatementPHIBerks27 min
Aug 17, 6:19 PM EDTSevere Thunderstorm WarningPHICarbon, Monroe41 min
Aug 17, 6:22 PM EDTSevere Thunderstorm WarningPHIMonroe, Northampton38 min
Aug 17, 6:23 PM EDTSevere Thunderstorm WarningPHIBerks, Lehigh52 min
Aug 17, 6:40 PM EDTFlash Flood WarningPHIBerks2 hr
Aug 17, 7:15 PM EDTSpecial Weather StatementPHIPike15 min
Aug 17, 7:34 PM EDTSpecial Weather StatementPHICarbon26 min
Aug 17, 7:39 PM EDTSpecial Weather StatementPHIMonroe51 min
Aug 17, 7:42 PM EDTSpecial Weather StatementPHIBucks, Northampton33 min

Nearby

Severe Thunderstorm Warnings in Pennsylvania, 2018Every severe thunderstorm warning in 2018

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.