Alert archive / Pennsylvania / Severe Thunderstorm Warnings in 2006

Severe Thunderstorm Warning 171, NWS Philadelphia/Mount Holly

July 18, 2006Delaware County, Montgomery County, Pennsylvania

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Jul 18, 2006, 7:09 PM EDT for Delaware County, Montgomery County, Pennsylvania. It was in force for 81 min. 3 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: Jul 18, 2006, 7:09 PM EDT (23:09 UTC)
Expired: Jul 18, 2006, 8:30 PM EDT
In force: 81 min
Issued by: NWS Philadelphia/Mount Holly
Area: Counties, with a storm outline in the text

Counties Delaware County, PA, Montgomery County, PA

The radar

The Philadelphia radar (KDIX), 93 km from the middle of the area, began a volume at 23:09 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
Jul 18, 7:15 PM EDT	TSTM WND DMG	1 N Audubon, PA	TREES AND POWER LINES DOWN IN LOWER PROVIDENCE TOWNSHIP.
Jul 18, 7:15 PM EDT	TSTM WND DMG	1 N Audubon, PA	TREES AND POWERLINES DOWN IN LOWER PROVIDENCE TWP.
Jul 18, 8:01 PM EDT	TSTM WND GST 43	5 Ne Norristown, PA	A 43 MPH THUNDERSTORM WIND GUST WAS MEASURED AT THE PHILADELPHIA WINGS FIELD 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
Jul 18, 12:38 PM EDT	Severe Thunderstorm Watch	SPC	7 hr
Jul 18, 6:37 PM EDT	Severe Thunderstorm Watch	SPC	6 hr

The nearest sounding before it

Phillips Aaf/Abe, MD (KAPG), launched 12:00Z, 11.2 hours before the alert went out and 91 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: 1100 J/kg
Mixed-layer CIN: -174 J/kg
Mixed-layer LCL: 1804 m above ground
0-6 km bulk shear: 14 kt
0-1 km storm-relative helicity: -17 m²/s²
0-3 km storm-relative helicity: 16 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.

000 
WUUS51 KPHI 182309
SVRPHI
PAC045-091-190030-
/O.NEW.KPHI.SV.W.0171.060718T2309Z-060719T0030Z/

BULLETIN - EAS ACTIVATION REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
709 PM EDT TUE JUL 18 2006

THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  DELAWARE COUNTY IN SOUTHEAST PENNSYLVANIA
  MONTGOMERY COUNTY IN SOUTHEAST PENNSYLVANIA

* UNTIL 830 PM EDT

* AT 700 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
  LINE OF SEVERE THUNDERSTORMS CAPABLE OF PRODUCING NICKEL SIZE
  HAIL...AND DAMAGING WINDS IN EXCESS OF 60 MPH.  THESE STORMS WERE
  LOCATED ALONG A LINE EXTENDING FROM 8 MILES WEST OF SPRING MOUNT TO
  37 MILES WEST OF LIMA...OR ALONG A LINE EXTENDING FROM 17 MILES
  EAST OF READING TO 16 MILES SOUTHEAST OF LANCASTER...AND MOVING
  EAST AT 15 MPH.

* SEVERE THUNDERSTORMS WILL BE NEAR...
  7 MILES SOUTH OF EAST GREENVILLE BY 730 PM EDT...
  SPRING MOUNT BY 740 PM EDT...
  COLLEGEVILLE BY 805 PM EDT...
  LANSDALE...KING OF PRUSSIA...NORRISTOWN AND 7 MILES NORTHWEST OF
  PLYMOUTH MEETING BY 830 PM EDT...

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.

LAT...LON 4034 7562 4016 7550 4005 7535 3993 7548
      3987 7557 3985 7539 4022 7519 4041 7552

$$

AMC/MPD

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 18, 4:51 PM EDT	Severe Thunderstorm Warning	PHI	Berks	56 min
Jul 18, 5:33 PM EDT	Severe Thunderstorm Warning	PHI	Lehigh, Northampton	57 min
Jul 18, 6:27 PM EDT	Severe Thunderstorm Warning	PHI	Chester	78 min
Jul 18, 7:25 PM EDT	Severe Thunderstorm Warning	PHI	Philadelphia	65 min
Jul 18, 7:37 PM EDT	Severe Thunderstorm Warning	PHI	Bucks	53 min

Nearby

Severe Thunderstorm Warnings in Pennsylvania, 2006 Every severe thunderstorm warning in 2006

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.