Alert archive / Pennsylvania / Severe Thunderstorm Warnings in 2009

Severe Thunderstorm Warning 59, NWS Philadelphia/Mount Holly

June 9, 2009Berks County, Chester County, Montgomery County, Pennsylvania

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Jun 9, 2009, 2:24 PM EDT for Berks County, Chester County, Montgomery County, Pennsylvania. It was in force for 66 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: Jun 9, 2009, 2:24 PM EDT (18:24 UTC)
Expired: Jun 9, 2009, 3:30 PM EDT
In force: 66 min
Issued by: NWS Philadelphia/Mount Holly
Area: Storm-based polygon

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

The radar

The Philadelphia radar (KDIX), 131 km from the middle of the area, began a volume at 18:25 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
Jun 9, 3:22 PM EDT	HAIL 1.25	Christiana, PA	HALF DOLLAR SIZE HAIL IN CHRISTIANA.
Jun 9, 3:40 PM EDT	HAIL 0.25	Coatesville, PA	SPOTTER REPORTED PEA SIZE HAIL AT COATESVILLE AIRPORT.

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
Jun 9, 1:31 PM EDT	Severe Thunderstorm Watch	SPC	6 hr

The nearest sounding before it

Phillips Aaf/Abe, MD (KAPG), launched 12:00Z, 6.4 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: 1272 J/kg
Mixed-layer CIN: -67 J/kg
Mixed-layer LCL: 804 m above ground
0-6 km bulk shear: 28 kt
0-1 km storm-relative helicity: 87 m²/s²
0-3 km storm-relative helicity: 108 m²/s²
Significant tornado parameter: 0.3
Supercell composite: 1.9

Open this sounding in Storm Lab

The text

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

000 
WUUS51 KPHI 091824
SVRPHI
PAC011-029-091-091930-
/O.NEW.KPHI.SV.W.0059.090609T1824Z-090609T1930Z/

BULLETIN - EAS ACTIVATION REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
224 PM EDT TUE JUN 9 2009

THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  SOUTH CENTRAL BERKS COUNTY IN EASTERN PENNSYLVANIA...
  WESTERN CHESTER COUNTY IN SOUTHEAST PENNSYLVANIA...
  EXTREME WEST CENTRAL MONTGOMERY COUNTY IN SOUTHEAST PENNSYLVANIA...

* UNTIL 330 PM EDT

* AT 224 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
  SEVERE THUNDERSTORM CAPABLE OF PRODUCING PENNY SIZE HAIL...AND
  DAMAGING WINDS IN EXCESS OF 60 MPH.  THIS STORM WAS LOCATED NEAR
  ELVERSON...OR 13 MILES SOUTH OF READING...AND MOVING EAST AT 10
  MPH. ANOTHER SEVERE THUNDERSTORM OVER EXTREME LANCASTER COUNTY SHOULD
  ALSO AFFECT WESTERN CHESTER COUNTY.

* THE SEVERE THUNDERSTORM WILL BE NEAR...
  8 MILES SOUTH OF BIRDSBORO AROUND 230 PM EDT...
  ELVERSON AROUND 235 PM EDT...
  GLENMOORE AROUND 305 PM EDT...
  7 MILES SOUTH OF CEDARVILLE AROUND 330 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.

IN ADDITION TO LARGE HAIL AND DAMAGING WINDS...CONTINUOUS CLOUD TO
GROUND LIGHTNING IS OCCURRING WITH THIS STORM. MOVE INDOORS
IMMEDIATELY LIGHTNING IS ONE OF NATURES NUMBER ONE KILLERS.
REMEMBER...IF YOU CAN HEAR THUNDER...YOU ARE CLOSE ENOUGH TO BE
STRUCK BY LIGHTNING.

A SEVERE THUNDERSTORM WATCH REMAINS IN EFFECT UNTIL 800 PM EDT
TUESDAY EVENING FOR NORTHEASTERN PENNSYLVANIA.

&&

LAT...LON 3985 7603 3987 7601 3992 7601 3993 7600
      3996 7600 4003 7595 4011 7595 4014 7590
      4017 7593 4031 7586 4024 7563 3979 7594
      3981 7605
TIME...MOT...LOC 1823Z 284DEG 7KT 4015 7586

$$

RNS

1 follow-up statement

000 
WWUS51 KPHI 091851
SVSPHI

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
251 PM EDT TUE JUN 9 2009

PAC011-091-091901-
/O.CAN.KPHI.SV.W.0059.000000T0000Z-090609T1930Z/
MONTGOMERY PA-BERKS PA-
251 PM EDT TUE JUN 9 2009

...THE SEVERE THUNDERSTORM WARNING FOR SOUTH CENTRAL BERKS AND
EXTREME WEST CENTRAL MONTGOMERY COUNTIES IS CANCELLED...

A SEVERE THUNDERSTORM WATCH REMAINS IN EFFECT UNTIL 800 PM EDT
TUESDAY EVENING FOR NORTHEASTERN PENNSYLVANIA.

LAT...LON 3985 7603 3987 7601 3992 7601 3993 7600
      3996 7600 4003 7595 4011 7595 4014 7590
      4015 7588 4021 7577 4021 7565 3979 7594
      3981 7605
TIME...MOT...LOC 1851Z 286DEG 7KT 3986 7599

$$

PAC029-091930-
/O.CON.KPHI.SV.W.0059.000000T0000Z-090609T1930Z/
CHESTER PA-
251 PM EDT TUE JUN 9 2009

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 330 PM EDT
FOR WESTERN CHESTER COUNTY...

AT 249 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR CONTINUED TO
INDICATE A SEVERE THUNDERSTORM CAPABLE OF PRODUCING PENNY SIZE
HAIL...AND DAMAGING WINDS IN EXCESS OF 60 MPH.  THIS STORM WAS
LOCATED NEAR HOMEVILLE...OR 18 MILES NORTHWEST OF NEWARK...MOVING
EAST AT 10 MPH.

THE SEVERE THUNDERSTORM WILL BE NEAR...
  8 MILES SOUTH OF PARKESBURG BY 305 PM EDT...
  COCHRANVILLE BY 315 PM EDT...

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A SEVERE THUNDERSTORM WATCH REMAINS IN EFFECT UNTIL 800 PM EDT
TUESDAY EVENING FOR NORTHEASTERN PENNSYLVANIA.

&&

LAT...LON 3985 7603 3987 7601 3992 7601 3993 7600
      3996 7600 4003 7595 4011 7595 4014 7590
      4015 7588 4021 7577 4021 7565 3979 7594
      3981 7605
TIME...MOT...LOC 1851Z 286DEG 7KT 3986 7599

$$

RNS

The office that day

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

Issued	Product	Office	Counties	Lasted
Jun 9, 4:17 AM EDT	Dense Fog Advisory	PHI		5 hr
Jun 9, 5:38 AM EDT	Severe Thunderstorm Warning	PHI	Berks	67 min
Jun 9, 7:20 AM EDT	Severe Thunderstorm Warning	PHI	Chester, Delaware, Montgomery, Philadelphia	55 min
Jun 9, 8:00 AM EDT	Severe Thunderstorm Warning	PHI	Delaware, Philadelphia	60 min
Jun 9, 8:06 AM EDT	Severe Thunderstorm Warning	PHI	Philadelphia	54 min
Jun 9, 8:20 AM EDT	Areal Flood Advisory	PHI	Delaware, Montgomery, Philadelphia	3 hr
Jun 9, 8:42 AM EDT	Areal Flood Advisory	PHI	Bucks	3 hr
Jun 9, 9:56 AM EDT	Flash Flood Warning	PHI	Chester	105 min
Jun 9, 1:49 PM EDT	Flash Flood Watch	PHI	Delaware, Philadelphia	5 hr
Jun 9, 2:20 PM EDT	Flash Flood Warning	PHI	Berks, Chester	3 hr
Jun 9, 2:59 PM EDT	Tornado Warning	PHI	Chester	32 min
Jun 9, 3:08 PM EDT	Tornado Warning	PHI	Chester	28 min
Jun 9, 3:14 PM EDT	Tornado Warning	PHI	Chester	46 min
Jun 9, 3:29 PM EDT	Severe Thunderstorm Warning	PHI	Chester	61 min

Nearby

Severe Thunderstorm Warnings in Pennsylvania, 2009 Every severe thunderstorm warning in 2009

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.