Alert archive / Pennsylvania / Severe Thunderstorm Warnings in 2007

Severe Thunderstorm Warning 20, NWS Philadelphia/Mount Holly

May 27, 2007Chester County, Montgomery County, Pennsylvania

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at May 27, 2007, 7:23 PM EDT for Chester County, Montgomery County, Pennsylvania. It was in force for 67 min. 1 report 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: May 27, 2007, 7:23 PM EDT (23:23 UTC)
Expired: May 27, 2007, 8:30 PM EDT
In force: 67 min
Issued by: NWS Philadelphia/Mount Holly
Area: Counties, with a storm outline in the text

Counties Chester County, PA, Montgomery County, PA

What was reported inside it

Time	Report	Where	Remark
May 27, 7:33 PM EDT	TSTM WND DMG	Pottsgrove, PA	TREES DOWN IN UPPER HANOVER TWP

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

The nearest sounding before it

Washington/Dulle, VA (KIAD), launched 12:00Z, 11.4 hours before the alert went out and 202 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: 224 J/kg
Mixed-layer CIN: -196 J/kg
Mixed-layer LCL: 1384 m above ground
0-6 km bulk shear: 21 kt
0-1 km storm-relative helicity: 9 m²/s²
0-3 km storm-relative helicity: 14 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 272323
SVRPHI
PAC029-091-280030-
/O.NEW.KPHI.SV.W.0020.070527T2323Z-070528T0030Z/

BULLETIN - EAS ACTIVATION REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
723 PM EDT SUN MAY 27 2007

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 830 PM EDT

* AT 718 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
  SEVERE THUNDERSTORM CAPABLE OF PRODUCING DAMAGING WINDS IN EXCESS
  OF 60 MPH.  THIS STORM WAS LOCATED NEAR POTTSTOWN...OR ABOUT 20
  MILES EAST OF READING...AND MOVING EAST AT 25 MPH.

* THE SEVERE THUNDERSTORM WILL BE NEAR...
  COLLEGEVILLE BY 730 PM EDT...
  7 MILES NORTH OF KING OF PRUSSIA AND 8 MILES SOUTH OF SOUDERTON BY
  740 PM EDT...

IN ADDITION TO 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.

WIND DAMAGE WITH THIS STORM WILL OCCUR WELL AHEAD OF ANY RAIN OR
LIGHTNING. DO NOT WAIT FOR THE SOUND OF THUNDER BEFORE TAKING COVER.
SEEK SHELTER IMMEDIATELY INSIDE A STURDY STRUCTURE AND STAY AWAY FROM
WINDOWS.

LAT...LON 4012 7593 4005 7582 3997 7552 4006 7539
      4028 7526 4043 7551 4024 7571

$$

NIERENBERG

The office that day

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

Issued	Product	Office	Counties	Lasted
May 27, 6:48 PM EDT	Severe Thunderstorm Warning	PHI	Bucks, Northampton	57 min

Nearby

Severe Thunderstorm Warnings in Pennsylvania, 2007 Every severe thunderstorm warning in 2007

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.