Alert archive / Pennsylvania / Severe Thunderstorm Warnings in 2009

Severe Thunderstorm Warning 98, NWS Philadelphia/Mount Holly

June 26, 2009Chester County, Montgomery County, Pennsylvania

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Jun 26, 2009, 6:23 PM EDT for Chester County, Montgomery County, Pennsylvania. It was in force for 52 min. 5 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 26, 2009, 6:23 PM EDT (22:23 UTC)
Expired: Jun 26, 2009, 7:15 PM EDT
In force: 52 min
Issued by: NWS Philadelphia/Mount Holly
Area: Storm-based polygon

Counties Chester County, PA, Montgomery County, PA

The radar

The Philadelphia radar (KDIX), 94 km from the middle of the area, began a volume at 22:25 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 26, 6:25 PM EDT	TSTM WND DMG	2 Ne Cedarville, PA	TREE DOWN IN POTTSTOWN
Jun 26, 6:38 PM EDT	HAIL 0.88	7 N Valley Forge, PA	NICKELS SIZE HAIL IN TRAPPE TWP.
Jun 26, 6:39 PM EDT	HAIL 0.75	5 Ene Cedarville, PA	PENNY SIZE HAIL IN SANATOGA.
Jun 26, 7:06 PM EDT	HAIL 0.88	7 E Pughtown, PA	NICKEL SIZE HAIL IN ROYERSFORD.
Jun 26, 7:06 PM EDT	HAIL 1	7 E Pughtown, PA	QUARTER SIZE HAIL IN ROYERSFORD.

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 26, 2:42 PM EDT	Severe Thunderstorm Watch	SPC	7 hr

The nearest sounding before it

Phillips Aaf/Abe, MD (KAPG), launched 12:00Z, 10.4 hours before the alert went out and 88 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: 1259 J/kg
Mixed-layer CIN: -73 J/kg
Mixed-layer LCL: 969 m above ground
0-6 km bulk shear: 24 kt
0-1 km storm-relative helicity: 29 m²/s²
0-3 km storm-relative helicity: 26 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.5

Open this sounding in Storm Lab

The text

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

000 
WUUS51 KPHI 262223
SVRPHI
PAC029-091-262315-
/O.NEW.KPHI.SV.W.0098.090626T2223Z-090626T2315Z/

BULLETIN - EAS ACTIVATION REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
623 PM EDT FRI JUN 26 2009

THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ HAS ISSUED A

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

* UNTIL 715 PM EDT

* AT 621 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
  SEVERE THUNDERSTORM CAPABLE OF PRODUCING GOLF BALL SIZE HAIL...AND
  DAMAGING WINDS IN EXCESS OF 60 MPH.  THIS STORM WAS LOCATED NEAR
  POTTSTOWN...OR 17 MILES EAST OF READING...AND MOVING SOUTHEAST AT
  25 MPH.

* THE SEVERE THUNDERSTORM WILL BE NEAR...
  COLLEGEVILLE AND PHOENIXVILLE AROUND 645 PM EDT...
  VALLEY FORGE AND 9 MILES NORTHEAST OF PAOLI AROUND 655 PM EDT...
  NORRISTOWN AND KING OF PRUSSIA AROUND 705 PM EDT...
  PLYMOUTH MEETING AROUND 710 PM EDT...

PRECAUTIONARY/PREPAREDNESS ACTIONS...

HAIL UP TO ONE INCH HAS BEEN REPORTED WITH THIS STORM. IF YOU ARE 
IN THE PATH OF THE STORM...TAKE IMMEDIATE ACTION TO PROTECT LIFE AND 
PROPERTY.

A SEVERE THUNDERSTORM WATCH REMAINS IN EFFECT UNTIL 1000 PM EDT 
FRIDAY EVENING FOR EASTERN PENNSYLVANIA.

&&

LAT...LON 4021 7576 4028 7565 4012 7520 4005 7536
      4006 7538 4005 7542 4002 7542 3999 7549
TIME...MOT...LOC 2222Z 304DEG 21KT 4026 7561

$$

SZATKOWSKI

The office that day

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

Issued	Product	Office	Counties	Lasted
Jun 26, 3:31 PM EDT	Severe Thunderstorm Warning	PHI	Monroe	59 min
Jun 26, 3:53 PM EDT	Severe Thunderstorm Warning	PHI	Carbon, Monroe	82 min
Jun 26, 4:51 PM EDT	Severe Thunderstorm Warning	PHI	Carbon, Monroe, Northampton	69 min
Jun 26, 5:35 PM EDT	Severe Thunderstorm Warning	PHI	Berks	55 min
Jun 26, 6:01 PM EDT	Severe Thunderstorm Warning	PHI	Bucks, Montgomery	59 min
Jun 26, 6:16 PM EDT	Severe Thunderstorm Warning	PHI	Bucks, Lehigh	59 min
Jun 26, 6:30 PM EDT	Severe Thunderstorm Warning	PHI	Berks	45 min
Jun 26, 6:41 PM EDT	Severe Thunderstorm Warning	PHI	Bucks	41 min
Jun 26, 6:57 PM EDT	Severe Thunderstorm Warning	PHI	Montgomery, Philadelphia	48 min
Jun 26, 7:10 PM EDT	Severe Thunderstorm Warning	PHI	Bucks, Montgomery, Philadelphia	50 min
Jun 26, 7:15 PM EDT	Severe Thunderstorm Warning	PHI	Chester, Delaware, Montgomery, Philadelphia	60 min
Jun 26, 7:28 PM EDT	Severe Thunderstorm Warning	PHI	Bucks, Montgomery, Philadelphia	92 min
Jun 26, 7:30 PM EDT	Severe Thunderstorm Warning	PHI	Berks	45 min
Jun 26, 7:45 PM EDT	Severe Thunderstorm Warning	PHI	Philadelphia	65 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.