Alert archive / Pennsylvania / Severe Thunderstorm Warnings in 2012

Severe Thunderstorm Warning 212, NWS Philadelphia/Mount Holly

September 8, 20126 counties in Pennsylvania

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Sep 8, 2012, 2:40 PM EDT for 6 counties in Pennsylvania. It was in force for 65 min. 6 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 8, 2012, 2:40 PM EDT (18:40 UTC)
Expired
Sep 8, 2012, 3:45 PM EDT
In force
65 min
Issued by
NWS Philadelphia/Mount Holly
Area
Storm-based polygon

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

The radar

The Philadelphia radar (KDIX), 125 km from the middle of the area, began a volume at 18:40 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 8, 3:00 PM EDTTSTM WND GST 53Reading Airport, PA53 MPH WIND GUST AT READING AIRPORT.
Sep 8, 3:05 PM EDTTSTM WND DMGReading, PALARGE TREE LIMBS DOWN IN READING.
Sep 8, 3:20 PM EDTTSTM WND DMGBlandon, PATREES DOWN IN BLANDON.
Sep 8, 3:41 PM EDTTSTM WND DMGUpper Saucon Twp, PANUMEROUS TREES AND POWER LINES DOWN ACROSS SOUTHEASTERN LEHIGH COUNTY... INCLUDING IN UPPER SAUCON TWP... UPPER MILFORD TWP... AND IN COOPERSBURG. SOME TREES DOWN ONTO HOUSES.
Sep 8, 3:48 PM EDTTSTM WND DMGCoopersburg, PATREES AND A POWER LINE DOWN IN COOPERSBURG.
Sep 8, 3:50 PM EDTTSTM WND DMGSpringtown, PATREE DOWN AT INTERSECTION OF OLD BETHLEHEM ROAD AND HILLTOP ROAD.

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 8, 12:15 PM EDTSevere Thunderstorm WatchSPC9 hr

The nearest sounding before it

Washington/Dulle, VA (KIAD), launched 12:00Z, 6.7 hours before the alert went out and 207 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 2012-09-08Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 252 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 2012-09-08The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 150 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
252 J/kg
Mixed-layer CIN
-81 J/kg
Mixed-layer LCL
638 m above ground
0-6 km bulk shear
39 kt
0-1 km storm-relative helicity
150 m²/s²
0-3 km storm-relative helicity
140 m²/s²
Significant tornado parameter
0.1
Supercell composite
1.0

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

242 
WUUS51 KPHI 081840
SVRPHI
PAC011-017-029-077-091-095-081945-
/O.NEW.KPHI.SV.W.0212.120908T1840Z-120908T1945Z/

BULLETIN - EAS ACTIVATION REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
240 PM EDT SAT SEP 8 2012

THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  BERKS COUNTY IN EASTERN PENNSYLVANIA...
  THIS INCLUDES THE CITY OF READING...
  LEHIGH COUNTY IN EASTERN PENNSYLVANIA...
  THIS INCLUDES THE CITY OF ALLENTOWN...
  NORTHAMPTON COUNTY IN EASTERN PENNSYLVANIA...
  THIS INCLUDES THE CITY OF EASTON...
  NORTHWESTERN BUCKS COUNTY IN SOUTHEAST PENNSYLVANIA...
  CHESTER COUNTY IN SOUTHEAST PENNSYLVANIA...
  NORTHWESTERN MONTGOMERY COUNTY IN SOUTHEAST PENNSYLVANIA...

* UNTIL 345 PM EDT

* AT 236 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
  LINE OF SEVERE THUNDERSTORMS CAPABLE OF PRODUCING DAMAGING WINDS IN
  EXCESS OF 60 MPH.  THESE STORMS WERE LOCATED ALONG A LINE EXTENDING
  FROM HAMBURG TO 17 MILES WEST OF HONEY BROOK TO 41 MILES WEST OF
  GLEN ROY...OR ALONG A LINE EXTENDING FROM 19 MILES NORTH OF READING
  TO LANCASTER TO 19 MILES NORTHWEST OF BALTIMORE...AND MOVING EAST
  AT 45 MPH.

* SEVERE THUNDERSTORMS WILL BE NEAR...
  SINKING SPRING...SHOEMAKERSVILLE AND LEESPORT AROUND 245 PM EDT...
  WANAMAKERS...WYOMISSING...READING AND LENHARTSVILLE AROUND 250 PM
  EDT...
  NEW TRIPOLI AND FLEETWOOD AROUND 255 PM EDT...
  JORDAN VALLEY AROUND 300 PM EDT...

PRECAUTIONARY/PREPAREDNESS ACTIONS...

WHILE NOT IMMEDIATELY LIKELY...A TORNADO MAY DEVELOP. IF A TORNADO 
IS SPOTTED...ACT QUICKLY AND MOVE TO A PLACE OF SAFETY IN A STURDY 
STRUCTURE...SUCH AS A BASEMENT OR SMALL INTERIOR ROOM.

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.

PLEASE REPORT HAIL OR STRONG WINDS TO THE NATIONAL WEATHER SERVICE BY
CALLING TOLL FREE...1-877-633-6772...WHEN YOU CAN DO SO SAFELY.

A SEVERE THUNDERSTORM WATCH REMAINS IN EFFECT UNTIL 1000 PM EDT
SATURDAY EVENING FOR DELAWARE AND NORTHEASTERN MARYLAND AND NEW
JERSEY AND EASTERN PENNSYLVANIA.

&&

LAT...LON 4054 7621 4058 7602 4063 7601 4067 7595
      4092 7511 4078 7515 4075 7519 4068 7520
      4068 7518 4032 7529 3976 7592 3972 7605
      3972 7613 3988 7600 3996 7600 4003 7594
      4011 7595 4014 7589 4038 7626
TIME...MOT...LOC 1839Z 248DEG 41KT 4060 7600 4006 7618
          3956 7673

$$

MPD
1 follow-up statement
581 
WWUS51 KPHI 081913
SVSPHI

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
313 PM EDT SAT SEP 8 2012

PAC011-017-029-077-091-095-081945-
/O.CON.KPHI.SV.W.0212.000000T0000Z-120908T1945Z/
BERKS PA-BUCKS PA-LEHIGH PA-MONTGOMERY PA-NORTHAMPTON PA-CHESTER PA-
313 PM EDT SAT SEP 8 2012

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 345 PM EDT
FOR CHESTER...NORTHAMPTON...NORTHWESTERN MONTGOMERY...LEHIGH...
NORTHWESTERN BUCKS AND BERKS COUNTIES...

AT 306 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR CONTINUED TO
INDICATE A LINE OF SEVERE THUNDERSTORMS CAPABLE OF PRODUCING DAMAGING
WINDS IN EXCESS OF 60 MPH.  THESE STORMS WERE LOCATED ALONG A LINE
EXTENDING FROM NEW TRIPOLI TO ELVERSON TO 18 MILES WEST OF GLEN
ROY...OR ALONG A LINE EXTENDING FROM 9 MILES SOUTH OF LEHIGHTON TO 13
MILES SOUTHEAST OF READING TO 25 MILES SOUTH OF LANCASTER...MOVING
EAST AT 45 MPH.

READING AIRPORT REPORTED WIND GUSTS BETWEEN 50 AND 55 MPH AT 300 PM 
WITH THE LINE OF STORMS. 

SEVERE THUNDERSTORMS WILL BE NEAR...
  PUGHTOWN...NEFFS...GLENMOORE AND COFFEETOWN BY 320 PM EDT...
  ZIONSVILLE...MOUNT VERNON...HOMEVILLE AND NORTHAMPTON BY 325 PM
  EDT...
  GLEN ROY AND GERYVILLE BY 330 PM EDT...

PRECAUTIONARY/PREPAREDNESS ACTIONS...

WHILE NOT IMMEDIATELY LIKELY...A TORNADO MAY STILL DEVELOP. IF A 
TORNADO IS SPOTTED...ACT QUICKLY AND MOVE TO A PLACE OF SAFETY IN A 
STURDY STRUCTURE...SUCH AS A BASEMENT OR SMALL INTERIOR ROOM.

IN ADDITION TO DAMAGING WINDS...FREQUENT CLOUD TO GROUND LIGHTNING 
IS OCCURRING WITH THESE STORM. MOVE INDOORS IMMEDIATELY! 
REMEMBER...IF YOU CAN HEAR THUNDER...YOU ARE CLOSE ENOUGH TO BE 
STRUCK BY LIGHTNING.

PLEASE REPORT HAIL OR STRONG WINDS TO THE NATIONAL WEATHER SERVICE BY
CALLING TOLL FREE...1-877-633-6772...WHEN YOU CAN DO SO SAFELY.

A SEVERE THUNDERSTORM WATCH REMAINS IN EFFECT UNTIL 1000 PM EDT
SATURDAY EVENING FOR DELAWARE AND NORTHEASTERN MARYLAND AND NEW
JERSEY AND EASTERN PENNSYLVANIA.

&&

LAT...LON 3988 7600 4011 7595 4014 7589 4024 7605
      4045 7610 4063 7600 4092 7511 4078 7515
      4075 7519 4068 7518 4032 7529 3976 7592
      3972 7613
TIME...MOT...LOC 1911Z 248DEG 41KT 4073 7571 4019 7574
          3970 7629

$$

MPD

The office that day

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

IssuedProductOfficeCountiesLasted
Sep 8, 2:52 PM EDTSevere Thunderstorm WarningPHICarbon, Monroe53 min
Sep 8, 3:45 PM EDTSevere Thunderstorm WarningPHIBucks, Lehigh, Monroe, Montgomery, Northampton60 min
Sep 8, 4:07 PM EDTSpecial Weather StatementPHIDelaware, Philadelphia83 min
Sep 8, 4:29 PM EDTSevere Thunderstorm WarningPHIBucks, Montgomery61 min

Nearby

Severe Thunderstorm Warnings in Pennsylvania, 2012Every severe thunderstorm warning in 2012

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.