Alert archive / Pennsylvania / Severe Thunderstorm Warnings in 2012

Severe Thunderstorm Warning 222, NWS Philadelphia/Mount Holly

September 18, 20124 counties in Pennsylvania

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Sep 18, 2012, 4:19 PM EDT for 4 counties in Pennsylvania. It was in force for 56 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: Sep 18, 2012, 4:19 PM EDT (20:19 UTC)
Expired: Sep 18, 2012, 5:15 PM EDT
In force: 56 min
Issued by: NWS Philadelphia/Mount Holly
Area: Storm-based polygon

Counties Berks County, PA, Chester County, PA, Delaware County, PA, Montgomery County, PA

The radar

The Philadelphia radar (KDIX), 122 km from the middle of the area, began a volume at 20:20 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

Time	Report	Where	Remark
Sep 18, 4:30 PM EDT	TSTM WND DMG	Robeson Twp, PA	MULTIPLE REPORTS OF TREES AND WIRES DOWN IN THE AREA.
Sep 18, 4:35 PM EDT	TSTM WND DMG	Oxford, PA	TREES DOWN.
Sep 18, 4:55 PM EDT	TSTM WND DMG	Pottstown, PA	TREE DOWN ON ROUTE 100.
Sep 18, 5:20 PM EDT	TSTM WND DMG	Glen Mills, PA	TREES DOWN.

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.

Issued	Product	Office	Lasted
Sep 18, 12:10 PM EDT	Tornado Watch	SPC	9 hr

The nearest sounding before it

Phillips Aaf/Abe, MD (KAPG), launched 12:00Z, 8.3 hours before the alert went out and 60 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-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

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: 330 J/kg
Mixed-layer CIN: -6 J/kg
Mixed-layer LCL: 519 m above ground
0-6 km bulk shear: 40 kt
0-1 km storm-relative helicity: 265 m²/s²
0-3 km storm-relative helicity: 275 m²/s²
Significant tornado parameter: 0.4
Supercell composite: 2.3

Open this sounding in Storm Lab

The text

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

896 
WUUS51 KPHI 182019
SVRPHI
PAC011-029-045-091-182115-
/O.NEW.KPHI.SV.W.0222.120918T2019Z-120918T2115Z/

BULLETIN - EAS ACTIVATION REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
419 PM EDT TUE SEP 18 2012

THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  SOUTHERN BERKS COUNTY IN EASTERN PENNSYLVANIA...
  CHESTER COUNTY IN SOUTHEAST PENNSYLVANIA...
  THIS INCLUDES THE CITY OF WEST CHESTER...
  WESTERN DELAWARE COUNTY IN SOUTHEAST PENNSYLVANIA...
  WESTERN MONTGOMERY COUNTY IN SOUTHEAST PENNSYLVANIA...

* UNTIL 515 PM EDT

* AT 416 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 NEW MORGAN TO 9 MILES NORTHWEST OF HOMEVILLE TO 13 MILES
  SOUTHWEST OF GLEN ROY...OR ALONG A LINE EXTENDING FROM 8 MILES
  SOUTH OF READING TO 12 MILES SOUTHEAST OF LANCASTER TO 24 MILES
  WEST OF NEWARK...AND MOVING NORTHEAST AT 45 MPH.

THE STRONGEST WINDS MAY OCCUR ALONG THE LEADING EDGE OF THE LINE.  

* SEVERE THUNDERSTORMS WILL BE NEAR...
  BIRDSBORO...NEW MORGAN...MOUNT VERNON AND GLEN ROY AROUND 425 PM
  EDT...
  HOMEVILLE...PARKESBURG...OXFORD AND ELVERSON AROUND 430 PM EDT...
  COCHRANVILLE AROUND 435 PM EDT...
  GILBERTSVILLE AROUND 440 PM EDT...

PRECAUTIONARY/PREPAREDNESS ACTIONS...

THIS LINE OF STORMS MAY CONTAIN LITTLE OR NO LIGHTNING. DO NOT 
WAIT TO HEAR THUNDER BEFORE TAKING COVER. SEEK SHELTER IMMEDIATELY 
INSIDE A STURDY STRUCTURE AND STAY AWAY FROM WINDOWS.

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 TORNADO WATCH REMAINS IN EFFECT UNTIL 700 PM EDT TUESDAY EVENING
FOR DELAWARE AND NORTHEASTERN MARYLAND AND NEW JERSEY AND EASTERN
PENNSYLVANIA.

&&

LAT...LON 3974 7610 3988 7600 3996 7600 4003 7594
      4011 7595 4014 7589 4023 7602 4026 7600
      4043 7552 4014 7537 3989 7536 3983 7565
      3977 7574 3972 7578 3972 7614
TIME...MOT...LOC 2018Z 248DEG 38KT 4023 7591 3995 7609
          3962 7617

$$

GORSE

1 follow-up statement

090 
WWUS51 KPHI 182039
SVSPHI

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
439 PM EDT TUE SEP 18 2012

PAC011-029-045-091-182115-
/O.CON.KPHI.SV.W.0222.000000T0000Z-120918T2115Z/
BERKS PA-MONTGOMERY PA-DELAWARE PA-CHESTER PA-
439 PM EDT TUE SEP 18 2012

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 515 PM EDT
FOR CHESTER...WESTERN DELAWARE...WESTERN MONTGOMERY AND SOUTHERN
BERKS COUNTIES...

AT 437 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 AMITY GARDENS TO HONEY BROOK TO 6 MILES SOUTH OF
OXFORD...OR ALONG A LINE EXTENDING FROM 11 MILES EAST OF READING TO
16 MILES WEST OF WEST CHESTER TO 12 MILES WEST OF NEWARK...MOVING
NORTHEAST AT 45 MPH.

SEVERE THUNDERSTORMS WILL BE NEAR...
  BECHTELSVILLE...STOWE...SOUTH COATESVILLE AND COATESVILLE BY 445 PM
  EDT...
  BALLY...KEMBLESVILLE...GLENMOORE AND CEDARVILLE BY 450 PM EDT...
  EAST GREENVILLE AND PUGHTOWN BY 455 PM EDT...

PRECAUTIONARY/PREPAREDNESS ACTIONS...

THIS LINE OF STORMS MAY CONTAIN LITTLE OR NO LIGHTNING. DO 
NOT WAIT FOR THUNDER BEFORE TAKING COVER. SEEK SHELTER IMMEDIATELY 
INSIDE A STURDY STRUCTURE AND STAY AWAY FROM WINDOWS.

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 TORNADO WATCH REMAINS IN EFFECT UNTIL 700 PM EDT TUESDAY EVENING
FOR DELAWARE AND NORTHEASTERN MARYLAND AND NEW JERSEY AND EASTERN
PENNSYLVANIA.

&&

LAT...LON 3974 7610 3988 7600 3996 7600 4003 7594
      4011 7595 4014 7589 4023 7602 4026 7600
      4043 7552 4014 7537 3989 7536 3983 7565
      3977 7574 3972 7578 3972 7614
TIME...MOT...LOC 2038Z 242DEG 40KT 4032 7570 4004 7588
          3971 7596

$$

GORSE

The office that day

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

Issued	Product	Office	Counties	Lasted
Sep 18, 4:13 AM EDT	Coastal Flood Advisory	PHI	Delaware, Philadelphia	21 hr
Sep 18, 12:58 PM EDT	Areal Flood Advisory	PHI	Carbon, Monroe	93 min
Sep 18, 12:59 PM EDT	Special Weather Statement	PHI	Berks, Lehigh	46 min
Sep 18, 1:05 PM EDT	Areal Flood Advisory	PHI	Berks, Lehigh	115 min
Sep 18, 1:32 PM EDT	Severe Thunderstorm Warning	PHI	Berks, Lehigh	43 min
Sep 18, 2:00 PM EDT	Special Weather Statement	PHI	Chester, Montgomery	60 min
Sep 18, 2:18 PM EDT	Special Weather Statement	PHI	Carbon, Monroe	57 min
Sep 18, 2:23 PM EDT	Severe Thunderstorm Warning	PHI	Chester, Montgomery	30 min
Sep 18, 2:25 PM EDT	Flash Flood Warning	PHI	Carbon, Lehigh, Monroe, Northampton	4 hr
Sep 18, 2:52 PM EDT	Severe Thunderstorm Warning	PHI	Bucks, Lehigh, Northampton	17 min
Sep 18, 3:07 PM EDT	Areal Flood Warning	PHI	Berks, Lehigh	8 hr
Sep 18, 3:16 PM EDT	Special Weather Statement	PHI	Monroe	59 min
Sep 18, 3:24 PM EDT	Special Weather Statement	PHI	Berks, Carbon	51 min
Sep 18, 3:52 PM EDT	Special Weather Statement	PHI	Chester	53 min
Sep 18, 4:05 PM EDT	Areal Flood Advisory	PHI	Berks, Lehigh	55 min
Sep 18, 4:23 PM EDT	Severe Thunderstorm Warning	PHI	Berks, Lehigh, Monroe, Northampton	52 min
Sep 18, 4:26 PM EDT	Areal Flood Advisory	PHI	Bucks, Lehigh, Northampton	3 hr
Sep 18, 4:35 PM EDT	Areal Flood Advisory	PHI	Bucks, Chester, Lehigh, Montgomery	55 min
Sep 18, 5:01 PM EDT	Severe Thunderstorm Warning	PHI	Bucks, Chester, Delaware, Lehigh, Montgomery, Northampton and 1 more	59 min
Sep 18, 5:12 PM EDT	Areal Flood Advisory	PHI	Bucks, Chester, Delaware, Montgomery	63 min
Sep 18, 5:12 PM EDT	Severe Thunderstorm Warning	PHI	Delaware, Philadelphia	78 min
Sep 18, 5:13 PM EDT	Severe Thunderstorm Warning	PHI	Monroe, Northampton	62 min
Sep 18, 6:00 PM EDT	Severe Thunderstorm Warning	PHI	Bucks, Montgomery, Philadelphia	60 min
Sep 18, 6:06 PM EDT	Areal Flood Advisory	PHI	Bucks, Montgomery, Philadelphia	54 min
Sep 18, 6:19 PM EDT	Areal Flood Warning	PHI	Carbon, Lehigh, Monroe, Northampton	16 hr
Sep 18, 6:54 PM EDT	Areal Flood Advisory	PHI	Bucks	111 min

Nearby

Severe Thunderstorm Warnings in Pennsylvania, 2012 Every 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.