Alert archive / Pennsylvania / Severe Thunderstorm Warnings in 2017

Severe Thunderstorm Warning 195, NWS Philadelphia/Mount Holly

September 5, 20175 counties in Pennsylvania

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Sep 5, 2017, 5:49 PM EDT for 5 counties in Pennsylvania. It was in force for 41 min. 7 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
Sep 5, 2017, 5:49 PM EDT (21:49 UTC)
Expired
Sep 5, 2017, 6:30 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 Berks County, PA, Bucks County, PA, Lehigh County, PA, Montgomery County, PA, Northampton County, PA

The radar

The Philadelphia radar (KDIX), 111 km from the middle of the area, began a volume at 21:53 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
Sep 5, 5:50 PM EDTTSTM WND DMGAmityville, PADOWNED TREES AND POWER LINES CLOSED A STRETCH OF ROUTE 662 IN AMITY TOWNSHIP. TIME ESTIMATED FROM RADAR.
Sep 5, 5:54 PM EDTTSTM WND DMG3 Ne Cedarville, PALARGE TREE LIMBS DOWN AND SHINGLES BLOWN OFF SOME HOUSES IN THE POTTSTOWN AREA.
Sep 5, 5:54 PM EDTTSTM WND DMGPottstown, PATWO POLES AND ALSO TREES DOWN BLOCKING SOME ROADWAYS.
Sep 5, 5:54 PM EDTHAIL 0.75Pottstown, PAPENNY SIZE HAIL REPORTED.
Sep 5, 5:54 PM EDTHAIL 1Pottstown, PAQUARTER SIZED HAIL ALONG WITH LARGE BRANCHES AND SHINGLES BLOWN OFF ROOF.
Sep 5, 5:56 PM EDTTSTM WND DMGHereford, PADOWNED TREES BLOCKING ROUTE 100 NEAR CHESTNUT STREET IN HEREFORD TOWNSHIP.
Sep 5, 6:04 PM EDTTSTM WND DMG2 W Green Lane, PATREES AND POWER LINES DOWN NEAR BECKER AND WOODLAND ROADS IN UPPER FREDERICK TOWNSHIP.

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
Sep 5, 3:26 PM EDTSevere Thunderstorm WatchSPC5 hr

The nearest sounding before it

Brookhaven, NY (KOKX), launched 12:00Z, 9.8 hours before the alert went out and 211 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, Brookhaven, NY at 12:00Z on 2017-09-05Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 217 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, Brookhaven, NY at 12:00Z on 2017-09-05The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 150 square meters per square second.19395878Sfc1 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
217 J/kg
Mixed-layer CIN
-103 J/kg
Mixed-layer LCL
902 m above ground
0-6 km bulk shear
51 kt
0-1 km storm-relative helicity
150 m²/s²
0-3 km storm-relative helicity
129 m²/s²
Significant tornado parameter
0.1
Supercell composite
0.8

Open this sounding in Storm Lab

The text

As transmitted.

735 
WUUS51 KPHI 052149
SVRPHI
PAC011-017-077-091-095-052230-
/O.NEW.KPHI.SV.W.0195.170905T2149Z-170905T2230Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Mount Holly NJ
549 PM EDT TUE SEP 5 2017

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...
  Northwestern Bucks County in southeastern Pennsylvania...
  Northampton County in eastern Pennsylvania...

* Until 630 PM EDT

* At 548 PM EDT, severe thunderstorms were located along a line
  extending from near Coffeetown to near Fleetwood to near Birdsboro,
  moving east-northeast at 40 mph.

  HAZARD...60 mph wind gusts and penny size hail. 

  SOURCE...Radar indicated. 

  IMPACT...Expect damage to trees and power lines. 

* Locations impacted include...
  Allentown, Reading, Easton, Bethlehem, Pottstown, Forks, Emmaus,
  Northampton, Quakertown, Perkasie, Wilson, Souderton, Bedminster,
  Hellertown, Nazareth, Birdsboro, Kutztown, Slatington, Fleetwood
  and Chalfont.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

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

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

&&

LAT...LON 4079 7556 4086 7528 4081 7519 4076 7518
      4074 7519 4073 7518 4070 7520 4061 7520
      4057 7519 4056 7516 4028 7515 4022 7589
      4052 7598
TIME...MOT...LOC 2148Z 252DEG 40KT 4061 7559 4043 7576 4024 7577 

HAIL...0.75IN
WIND...60MPH
 
$$

JRK
3 follow-up statements
311 
WWUS51 KPHI 052200
SVSPHI

Severe Weather Statement
National Weather Service Mount Holly NJ
600 PM EDT TUE SEP 5 2017

PAC011-017-077-091-095-052230-
/O.CON.KPHI.SV.W.0195.000000T0000Z-170905T2230Z/
Berks PA-Montgomery PA-Lehigh PA-Bucks PA-Northampton PA-
600 PM EDT TUE SEP 5 2017

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 630 PM EDT
FOR EASTERN BERKS...NORTHWESTERN MONTGOMERY...LEHIGH...NORTHWESTERN
BUCKS AND NORTHAMPTON COUNTIES...

At 559 PM EDT, severe thunderstorms were located along a line
extending from Northampton to near Bally to near Pottstown, moving
east at 45 mph.

HAZARD...60 mph wind gusts and quarter size hail. 

SOURCE...Radar indicated. 

IMPACT...Minor damage to vehicles is possible. Expect damage to 
         trees and power lines. 

These severe storms will be near...
  Northampton, Bath, Lehigh University, Beersville and Geryville 
  around 605 PM EDT. 
  Allentown, Bethlehem, Emmaus and Steuben around 610 PM EDT. 
  Forks, Wilson, Nazareth, Belfast, West Easton, Tatamy, Glendon and 
  Old Orchard around 615 PM EDT. 
  Easton, Quakertown, Souderton, Hellertown, Hatfield and Pleasant 
  Valley around 620 PM EDT. 
  Perkasie, Springtown and Fricks around 625 PM EDT. 
  Bedminster, Chalfont, Dublin, Ferndale, Riegelsville, Revere and 
  Ottsville around 630 PM EDT. 

Other locations impacted by these severe thunderstorms include
Harleysville, Boyertown, Pottsgrove, Hokendauqua, South Pottstown,
Stockertown, Red Hill, Amity Gardens, Eastlawn Gardens and North
Catasauqua.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Remain alert for a possible tornado! Tornadoes can develop quickly
from severe thunderstorms. If you spot a tornado go at once into the
basement or small central room in a sturdy structure.

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 this storm. Move indoors
immediately. Remember...if you can hear thunder...you are close
enough to be struck by lightning.

&&

LAT...LON 4077 7555 4082 7546 4086 7528 4081 7519
      4076 7518 4074 7519 4073 7518 4070 7520
      4061 7520 4057 7519 4056 7516 4028 7515
      4023 7573 4051 7582 4064 7571
TIME...MOT...LOC 2159Z 251DEG 40KT 4066 7548 4047 7561 4028 7562 

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

JRK
633 
WWUS51 KPHI 052219
SVSPHI

Severe Weather Statement
National Weather Service Mount Holly NJ
619 PM EDT TUE SEP 5 2017

PAC011-052227-
/O.CAN.KPHI.SV.W.0195.000000T0000Z-170905T2230Z/
Berks PA-
619 PM EDT TUE SEP 5 2017

...THE SEVERE THUNDERSTORM WARNING FOR EASTERN BERKS COUNTY IS
CANCELLED...

The storms which prompted the warning have moved out of the warned 
area. Therefore, the warning has been cancelled.

A severe thunderstorm watch remains in effect until 900 PM EDT for
northwestern New Jersey...and eastern and southeastern Pennsylvania.

LAT...LON 4081 7519 4078 7518 4060 7520 4057 7519
      4056 7516 4028 7515 4025 7551 4025 7552
      4043 7554 4045 7553 4046 7555 4058 7557
      4080 7549 4086 7527
TIME...MOT...LOC 2217Z 251DEG 40KT 4081 7531 4052 7539 4033 7540 

$$

PAC017-077-091-095-052230-
/O.CON.KPHI.SV.W.0195.000000T0000Z-170905T2230Z/
Montgomery PA-Lehigh PA-Bucks PA-Northampton PA-
619 PM EDT TUE SEP 5 2017

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 630 PM EDT
FOR NORTH CENTRAL MONTGOMERY...SOUTHEASTERN LEHIGH...NORTHWESTERN
BUCKS AND NORTHAMPTON COUNTIES...

At 617 PM EDT, severe thunderstorms were located along a line
extending from near Wind Gap to near Hellertown to near Green Lane,
moving east at 45 mph.

HAZARD...70 mph wind gusts and quarter size hail. 

SOURCE...Doppler radar and trained weather spotters. These storms 
         have produced wind damage across Berks and upper portions 
         of Montgomery County.  

IMPACT...Minor damage to vehicles is possible. Expect considerable 
         tree damage. Wind damage is also likely to mobile homes, 
         roofs, and outbuildings. 

These severe storms will be near...
  Nazareth, Wind Gap, Belfast and Tatamy around 620 PM EDT. 
  Pleasant Valley and Springtown around 625 PM EDT. 
  Bedminster, Chalfont, Dublin, Ferndale, West Easton, Riegelsville, 
  Glendon, Revere, Ottsville and Old Orchard around 630 PM EDT. 

Other locations impacted by these severe thunderstorms include
Harleysville, Chapman, Coopersburg, Coplay, Sellersville, Fountain
Hill, Fullerton, Hokendauqua, Richlandtown and Stockertown.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Remain alert for a possible tornado! Tornadoes can develop quickly
from severe thunderstorms. If you spot a tornado go at once into the
basement or small central room in a sturdy structure.

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 this storm. Move indoors 
immediately. Remember...if you can hear thunder...you are close 
enough to be struck by lightning.

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

&&

LAT...LON 4081 7519 4078 7518 4060 7520 4057 7519
      4056 7516 4028 7515 4025 7551 4025 7552
      4043 7554 4045 7553 4046 7555 4058 7557
      4080 7549 4086 7527
TIME...MOT...LOC 2217Z 251DEG 40KT 4081 7531 4052 7539 4033 7540 

TORNADO...POSSIBLE
HAIL...1.00IN
WIND...70MPH
 
$$

JRK
202 
WWUS51 KPHI 052228
SVSPHI

Severe Weather Statement
National Weather Service Mount Holly NJ
628 PM EDT TUE SEP 5 2017

PAC017-077-091-095-052237-
/O.EXP.KPHI.SV.W.0195.000000T0000Z-170905T2230Z/
Montgomery PA-Lehigh PA-Bucks PA-Northampton PA-
628 PM EDT TUE SEP 5 2017

...THE SEVERE THUNDERSTORM WARNING FOR NORTH CENTRAL MONTGOMERY...
SOUTHEASTERN LEHIGH...NORTHWESTERN BUCKS AND NORTHAMPTON COUNTIES
WILL EXPIRE AT 630 PM EDT...
    
The storms which prompted the warning have moved out of the 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 900 PM EDT for
northwestern New Jersey...and eastern and southeastern Pennsylvania.

LAT...LON 4081 7519 4078 7518 4060 7520 4057 7519
      4056 7516 4028 7515 4025 7551 4025 7552
      4043 7554 4045 7553 4046 7555 4058 7557
      4080 7549 4086 7527
TIME...MOT...LOC 2227Z 252DEG 40KT 4084 7519 4055 7527 4036 7528 

$$

JRK

The office that day

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

IssuedProductOfficeCountiesLasted
Sep 5, 3:59 PM EDTSpecial Weather StatementPHIBerks, Lehigh31 min
Sep 5, 4:08 PM EDTSevere Thunderstorm WarningPHIBerks, Carbon, Lehigh, Northampton52 min
Sep 5, 4:34 PM EDTAreal Flood AdvisoryPHIBerks6 hr
Sep 5, 4:54 PM EDTSevere Thunderstorm WarningPHIBerks, Carbon, Lehigh, Monroe, Northampton51 min
Sep 5, 5:14 PM EDTFlash Flood WarningPHIBerks4 hr
Sep 5, 5:19 PM EDTSevere Thunderstorm WarningPHIBerks, Chester, Montgomery56 min
Sep 5, 5:22 PM EDTAreal Flood AdvisoryPHINorthampton4 hr
Sep 5, 5:30 PM EDTFlash Flood WarningPHIBerks4 hr
Sep 5, 6:03 PM EDTAreal Flood AdvisoryPHILehigh, Northampton3 hr
Sep 5, 6:19 PM EDTSpecial Weather StatementPHIChester, Delaware41 min
Sep 5, 6:26 PM EDTSevere Thunderstorm WarningPHIBucks, Lehigh, Northampton49 min
Sep 5, 6:44 PM EDTSpecial Weather StatementPHIBucks31 min

Nearby

Severe Thunderstorm Warnings in Pennsylvania, 2017Every severe thunderstorm warning in 2017

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.