Alert archive / Pennsylvania / Severe Thunderstorm Warnings in 2012

Severe Thunderstorm Warning 183, NWS Philadelphia/Mount Holly

August 9, 2012Chester County, Montgomery County, Pennsylvania

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Aug 9, 2012, 3:20 PM EDT for Chester County, Montgomery County, Pennsylvania. It was in force for 55 min. 2 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 9, 2012, 3:20 PM EDT (19:20 UTC)
Expired: Aug 9, 2012, 4:15 PM EDT
In force: 55 min
Issued by: NWS Philadelphia/Mount Holly
Area: Storm-based polygon

Counties Chester County, PA, Montgomery County, PA

The radar

The Philadelphia radar (KDIX), 110 km from the middle of the area, began a volume at 19:24 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
Aug 9, 3:30 PM EDT	HAIL 0.75	Pottstown, PA
Aug 9, 3:36 PM EDT	TSTM WND DMG	South Coventry Twp, PA	TREES DOWN

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

The nearest sounding before it

Phillips Aaf/Abe, MD (KAPG), launched 12:00Z, 7.3 hours before the alert went out and 89 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: 1906 J/kg
Mixed-layer CIN: -18 J/kg
Mixed-layer LCL: 754 m above ground
0-6 km bulk shear: 10 kt
0-1 km storm-relative helicity: 46 m²/s²
0-3 km storm-relative helicity: 37 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

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

511 
WUUS51 KPHI 091920
SVRPHI
PAC029-091-092015-
/O.NEW.KPHI.SV.W.0183.120809T1920Z-120809T2015Z/

BULLETIN - EAS ACTIVATION REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
320 PM EDT THU AUG 9 2012

THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  NORTHEASTERN CHESTER COUNTY IN SOUTHEAST PENNSYLVANIA...
  WESTERN MONTGOMERY COUNTY IN SOUTHEAST PENNSYLVANIA...

* UNTIL 415 PM EDT

* AT 319 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
  SEVERE THUNDERSTORM CAPABLE OF PRODUCING QUARTER SIZE HAIL...AND
  DAMAGING WINDS IN EXCESS OF 60 MPH.  THIS STORM WAS LOCATED NEAR
  PUGHTOWN...OR 15 MILES SOUTHEAST OF READING...AND MOVING EAST AT 20
  MPH.

* THE SEVERE THUNDERSTORM WILL BE NEAR...
  CEDARVILLE AND PUGHTOWN AROUND 335 PM EDT...
  CHESTER SPRINGS AROUND 340 PM EDT...
  ROYERSFORD AND PHOENIXVILLE AROUND 355 PM EDT...
  TRAPPE AROUND 405 PM EDT...
  COLLEGEVILLE AND SCHWENKSVILLE AROUND 410 PM EDT...

PRECAUTIONARY/PREPAREDNESS ACTIONS...

THIS IS A DANGEROUS STORM. IF YOU ARE IN ITS PATH...PREPARE
IMMEDIATELY FOR DAMAGING WINDS...LARGE HAIL...AND DEADLY CLOUD TO
GROUND LIGHTNING. PEOPLE OUTSIDE SHOULD MOVE TO A SHELTER...
PREFERABLY INSIDE A STRONG BUILDING BUT 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.

&&

LAT...LON 4017 7583 4024 7570 4026 7568 4035 7540
      4010 7533 4007 7584
TIME...MOT...LOC 1920Z 263DEG 16KT 4016 7574

$$

HEAVENER

2 follow-up statements

514 
WWUS51 KPHI 091949
SVSPHI

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
349 PM EDT THU AUG 9 2012

PAC029-091-092015-
/O.CON.KPHI.SV.W.0183.000000T0000Z-120809T2015Z/
MONTGOMERY PA-CHESTER PA-
349 PM EDT THU AUG 9 2012

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 415 PM EDT
FOR NORTHEASTERN CHESTER AND WESTERN MONTGOMERY COUNTIES...

AT 345 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR CONTINUED TO
INDICATE A SEVERE THUNDERSTORM CAPABLE OF PRODUCING QUARTER SIZE
HAIL...AND DAMAGING WINDS IN EXCESS OF 60 MPH.  THIS STORM WAS
LOCATED NEAR SPRING CITY...OR 15 MILES NORTH OF WEST CHESTER...MOVING
EAST AT 20 MPH.

THE SEVERE THUNDERSTORM WILL BE NEAR...
  SPRING CITY...ROYERSFORD AND PHOENIXVILLE BY 355 PM EDT...
  TRAPPE BY 405 PM EDT...
  EVANSBURG...AUDUBON...SCHWENKSVILLE AND COLLEGEVILLE BY 410 PM
  EDT...
  EAGLEVILLE AND SKIPPACK BY 415 PM EDT...

PRECAUTIONARY/PREPAREDNESS ACTIONS...

THIS IS A DANGEROUS STORM. IF YOU ARE IN ITS PATH...PREPARE
IMMEDIATELY FOR DAMAGING WINDS...DESTRUCTIVE HAIL...AND DEADLY CLOUD
TO GROUND LIGHTNING. PEOPLE OUTSIDE SHOULD MOVE TO A SHELTER...
PREFERABLY INSIDE A STRONG BUILDING BUT 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.

&&

LAT...LON 4028 7564 4035 7540 4010 7533 4008 7567
      4025 7569
TIME...MOT...LOC 1949Z 263DEG 16KT 4018 7557

$$

HEAVENER

246 
WWUS51 KPHI 092001
SVSPHI

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
401 PM EDT THU AUG 9 2012

PAC029-092011-
/O.CAN.KPHI.SV.W.0183.000000T0000Z-120809T2015Z/
CHESTER PA-
401 PM EDT THU AUG 9 2012

...THE SEVERE THUNDERSTORM WARNING FOR NORTHEASTERN CHESTER COUNTY IS
CANCELLED...

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.

LAT...LON 4035 7540 4010 7533 4009 7546 4011 7547
      4013 7546 4013 7550 4014 7551 4016 7550
      4015 7552 4018 7555 4030 7558
TIME...MOT...LOC 2001Z 263DEG 16KT 4019 7550

$$

PAC091-092015-
/O.CON.KPHI.SV.W.0183.000000T0000Z-120809T2015Z/
MONTGOMERY PA-
401 PM EDT THU AUG 9 2012

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 415 PM EDT
FOR WESTERN MONTGOMERY COUNTY...

AT 358 PM EDT...A SEVERE THUNDERSTORM WAS REPORTED CAPABLE OF
PRODUCING QUARTER SIZE HAIL...AND DAMAGING WINDS IN EXCESS OF 60 MPH.
 THIS STORM WAS LOCATED NEAR ROYERSFORD...OR 16 MILES NORTH OF WEST
CHESTER...MOVING EAST AT 20 MPH.

THE SEVERE THUNDERSTORM WILL BE NEAR...
  EVANSBURG...COLLEGEVILLE...AUDUBON AND SCHWENKSVILLE BY 410 PM
  EDT...
  SKIPPACK...EAGLEVILLE...TROOPER AND WEST NORRITON BY 415 PM EDT...

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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.

&&

LAT...LON 4035 7540 4010 7533 4009 7546 4011 7547
      4013 7546 4013 7550 4014 7551 4016 7550
      4015 7552 4018 7555 4030 7558
TIME...MOT...LOC 2001Z 263DEG 16KT 4019 7550

$$

HEAVENER

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 9, 1:00 PM EDT	Special Weather Statement	PHI	Lehigh	60 min
Aug 9, 1:22 PM EDT	Severe Thunderstorm Warning	PHI	Bucks, Montgomery	68 min
Aug 9, 1:26 PM EDT	Areal Flood Advisory	PHI	Bucks, Montgomery	3 hr
Aug 9, 1:33 PM EDT	Special Weather Statement	PHI	Northampton	57 min
Aug 9, 1:42 PM EDT	Special Weather Statement	PHI	Monroe	63 min
Aug 9, 1:45 PM EDT	Special Weather Statement	PHI	Berks	60 min
Aug 9, 2:13 PM EDT	Severe Thunderstorm Warning	PHI	Berks	77 min
Aug 9, 2:20 PM EDT	Severe Thunderstorm Warning	PHI	Northampton	70 min
Aug 9, 2:25 PM EDT	Severe Thunderstorm Warning	PHI	Bucks	65 min
Aug 9, 3:03 PM EDT	Special Weather Statement	PHI	Monroe	87 min
Aug 9, 3:05 PM EDT	Special Weather Statement	PHI	Chester, Montgomery	85 min
Aug 9, 3:11 PM EDT	Areal Flood Advisory	PHI	Carbon, Monroe	6 hr
Aug 9, 3:39 PM EDT	Special Weather Statement	PHI	Bucks	66 min
Aug 9, 3:57 PM EDT	Areal Flood Advisory	PHI	Chester, Montgomery	104 min
Aug 9, 3:57 PM EDT	Severe Thunderstorm Warning	PHI	Bucks, Montgomery	63 min
Aug 9, 4:18 PM EDT	Special Weather Statement	PHI	Bucks	57 min
Aug 9, 4:33 PM EDT	Severe Thunderstorm Warning	PHI	Bucks	57 min
Aug 9, 4:57 PM EDT	Severe Thunderstorm Warning	PHI	Bucks	78 min
Aug 9, 5:06 PM EDT	Areal Flood Advisory	PHI	Bucks	3 hr
Aug 9, 5:26 PM EDT	Flash Flood Warning	PHI	Bucks	2 hr
Aug 9, 7:01 PM EDT	Special Weather Statement	PHI	Berks	59 min
Aug 9, 7:10 PM EDT	Severe Thunderstorm Warning	PHI	Berks, Carbon, Lehigh	80 min
Aug 9, 7:40 PM EDT	Special Weather Statement	PHI	Carbon, Monroe	95 min
Aug 9, 7:46 PM EDT	Areal Flood Advisory	PHI	Berks	3 hr

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.