Alert archive / Pennsylvania / Severe Thunderstorm Warnings in 2016

Severe Thunderstorm Warning 170, NWS Philadelphia/Mount Holly

August 12, 2016Chester County, Delaware County, Montgomery County, Pennsylvania

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Aug 12, 2016, 4:49 PM EDT for Chester County, Delaware County, Montgomery County, Pennsylvania. It was in force for 41 min. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued
Aug 12, 2016, 4:49 PM EDT (20:49 UTC)
Expired
Aug 12, 2016, 5:30 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 Chester County, PA, Delaware County, PA, Montgomery County, PA

The radar

The Philadelphia radar (KDIX), 85 km from the middle of the area, began a volume at 20:49 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.

The nearest sounding before it

Washington/Dulle, VA (KIAD), launched 12:00Z, 8.8 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 2016-08-12Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 756 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 2016-08-12The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 76 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
756 J/kg
Mixed-layer CIN
-110 J/kg
Mixed-layer LCL
1172 m above ground
0-6 km bulk shear
17 kt
0-1 km storm-relative helicity
76 m²/s²
0-3 km storm-relative helicity
103 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

623 
WUUS51 KPHI 122049
SVRPHI
PAC029-045-091-122130-
/O.NEW.KPHI.SV.W.0170.160812T2049Z-160812T2130Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
449 PM EDT FRI AUG 12 2016

THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ  HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  NORTHEASTERN CHESTER COUNTY IN SOUTHEASTERN PENNSYLVANIA...
  NORTHERN DELAWARE COUNTY IN SOUTHEASTERN PENNSYLVANIA...
  SOUTHERN MONTGOMERY COUNTY IN SOUTHEASTERN PENNSYLVANIA...

* UNTIL 530 PM EDT

* AT 448 PM EDT...A SEVERE THUNDERSTORM WAS LOCATED OVER
  LIONVILLE...OR 7 MILES NORTH OF WEST CHESTER...MOVING EAST AT 35
  MPH.

  HAZARD...60 MPH WIND GUSTS. 

  SOURCE...RADAR INDICATED. 

  IMPACT...EXPECT DAMAGE TO ROOFS...SIDING...AND TREES. 

* LOCATIONS IMPACTED INCLUDE...
  WEST CHESTER...NORRISTOWN...PHOENIXVILLE...LANSDALE...
  WEST NORRITON...EAST NORRITON...WESTTOWN...DOWNINGTOWN...
  CONSHOHOCKEN...AMBLER...COLLEGEVILLE...ROYERSFORD...NARBERTH...
  TRAPPE...EAST LANSDOWNE...VALLEY FORGE...MARSHALLTON...
  RADNOR TOWNSHIP AND TROUT LAKE.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

FOR YOUR PROTECTION MOVE TO AN INTERIOR ROOM ON THE LOWEST FLOOR OF A
BUILDING AS THIS STORM MOVES THROUGH.

&&

LAT...LON 4020 7576 4024 7543 4023 7517 4022 7516
      4009 7522 4005 7526 4001 7521 3997 7528
      3994 7525 3992 7572
TIME...MOT...LOC 2048Z 270DEG 30KT 4007 7563 

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

JJM
1 follow-up statement
476 
WWUS51 KPHI 122121
SVSPHI

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
521 PM EDT FRI AUG 12 2016

PAC029-045-091-122130-
/O.CON.KPHI.SV.W.0170.000000T0000Z-160812T2130Z/
CHESTER PA-DELAWARE PA-MONTGOMERY PA-
521 PM EDT FRI AUG 12 2016

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 530 PM EDT
FOR NORTHEASTERN CHESTER...NORTHEASTERN DELAWARE AND SOUTHEASTERN
MONTGOMERY COUNTIES...

AT 520 PM EDT...A SEVERE THUNDERSTORM WAS LOCATED OVER
CONSHOHOCKEN... OR 8 MILES NORTHWEST OF PHILADELPHIA...MOVING EAST
AT 35 MPH.

HAZARD...60 MPH WIND GUSTS. 

SOURCE...RADAR INDICATED. 

IMPACT...EXPECT DAMAGE TO...SIDING...AND TREES. 

LOCATIONS IMPACTED INCLUDE...
NORRISTOWN...PHOENIXVILLE...WEST NORRITON...EAST NORRITON...
CONSHOHOCKEN...AMBLER...COLLEGEVILLE...NARBERTH...TRAPPE...
 PLYMOUTH MEETING...VALLEY FORGE...BRYN MAWR...KING OF PRUSSIA...
 RADNOR TOWNSHIP...TROUT LAKE...PAOLI...NEWTOWN SQUARE...
 BROOMALL AND SKIPPACK.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

FOR YOUR PROTECTION MOVE TO AN INTERIOR ROOM ON THE LOWEST FLOOR OF A
BUILDING.

HEAVY RAINFALL IS OCCURRING WITH THIS STORM...AND MAY LEAD TO FLASH
FLOODING. DO NOT DRIVE YOUR VEHICLE THROUGH FLOODED ROADWAYS.

&&

LAT...LON 4022 7542 4023 7517 4022 7516 4009 7522
      4005 7526 4001 7521 3997 7528 3996 7527
      3996 7528 3999 7549 4020 7552
TIME...MOT...LOC 2120Z 270DEG 30KT 4007 7528 

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

JJM

The office that day

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

IssuedProductOfficeCountiesLasted
Aug 11, 10:39 PM EDTSpecial Weather StatementPHICarbon, Lehigh, Monroe, Northampton51 min
Aug 11, 10:57 PM EDTAreal Flood AdvisoryPHICarbon, Lehigh, Monroe, Northampton4 hr
Aug 11, 11:13 PM EDTFlash Flood WarningPHICarbon, Monroe, Northampton4 hr
Aug 12, 3:04 AM EDTSpecial Weather StatementPHILehigh, Northampton56 min
Aug 12, 3:38 PM EDTHeat AdvisoryPHICarbon, Monroe27 hr
Aug 12, 3:53 PM EDTSpecial Weather StatementPHICarbon, Monroe52 min
Aug 12, 4:03 PM EDTSpecial Weather StatementPHIBerks, Chester57 min
Aug 12, 4:45 PM EDTSpecial Weather StatementPHILehigh, Northampton60 min

Nearby

Severe Thunderstorm Warnings in Pennsylvania, 2016Every severe thunderstorm warning in 2016

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.