Alert archive / Pennsylvania / Severe Thunderstorm Warnings in 2007

Severe Thunderstorm Warning 214, NWS Philadelphia/Mount Holly

August 17, 2007Montgomery County, Pennsylvania

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Aug 17, 2007, 7:56 PM EDT for Montgomery County, Pennsylvania. It was in force for 19 min. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued: Aug 17, 2007, 7:56 PM EDT (23:56 UTC)
Expired: Aug 17, 2007, 8:15 PM EDT
In force: 19 min
Issued by: NWS Philadelphia/Mount Holly
Area: Counties, with a storm outline in the text

County Montgomery County, PA

The radar

The Philadelphia radar (KDIX), 67 km from the middle of the area, began a volume at 23:57 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.

The watch it was issued in

The SPC watch in force over the same counties when this warning went out.

Issued	Product	Office	Lasted
Aug 17, 1:37 PM EDT	Severe Thunderstorm Watch	SPC	6 hr

The nearest sounding before it

Brookhaven, NY (KOKX), launched 12:00Z, 11.9 hours before the alert went out and 213 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: 120 J/kg
Mixed-layer CIN: -267 J/kg
Mixed-layer LCL: 1465 m above ground
0-6 km bulk shear: 43 kt
0-1 km storm-relative helicity: -31 m²/s²
0-3 km storm-relative helicity: 44 m²/s²
Significant tornado parameter: 0.0
Supercell composite: -0.4

Open this sounding in Storm Lab

The text

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

000 
WUUS51 KPHI 172356
SVRPHI
PAC091-180015-
/O.NEW.KPHI.SV.W.0214.070817T2356Z-070818T0015Z/

BULLETIN - EAS ACTIVATION REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
756 PM EDT FRI AUG 17 2007

THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  EAST CENTRAL MONTGOMERY COUNTY IN SOUTHEAST PENNSYLVANIA...

* UNTIL 815 PM EDT

* AT 753 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 WILLOW GROVE...OR ABOUT 8
  MILES NORTH OF PHILADELPHIA...AND MOVING EAST AT 55 MPH.

* OTHER LOCATIONS IN THE WARNING INCLUDE BUT ARE NOT LIMITED TO
  WYNDMOOR...WYNCOTE...SPRING HOUSE...ORELAND...MAPLE GLEN...
  JENKINTOWN...HORSHAM...HATBORO...GLENSIDE...FORT WASHINGTON AND
  FLOURTOWN

LAT...LON 4006 7514 4008 7518 4008 7520 4009 7522
      4009 7523 4022 7523 4018 7510 4007 7510
TIME...MOT...LOC 2356Z 268DEG 49KT 4013 7509

$$

JJM

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 17, 1:48 PM EDT	Severe Thunderstorm Warning	PHI	Chester	72 min
Aug 17, 2:07 PM EDT	Severe Thunderstorm Warning	PHI	Carbon	68 min
Aug 17, 2:14 PM EDT	Tornado Warning	PHI	Chester	46 min
Aug 17, 2:19 PM EDT	Tornado Warning	PHI	Carbon	26 min
Aug 17, 2:20 PM EDT	Severe Thunderstorm Warning	PHI	Northampton	70 min
Aug 17, 2:36 PM EDT	Severe Thunderstorm Warning	PHI	Delaware	54 min
Aug 17, 2:41 PM EDT	Severe Thunderstorm Warning	PHI	Monroe, Northampton	79 min
Aug 17, 2:43 PM EDT	Severe Thunderstorm Warning	PHI	Bucks	62 min
Aug 17, 2:45 PM EDT	Tornado Warning	PHI	Carbon, Northampton	45 min
Aug 17, 2:54 PM EDT	Severe Thunderstorm Warning	PHI	Lehigh	66 min
Aug 17, 4:42 PM EDT	Severe Thunderstorm Warning	PHI	Carbon	19 min
Aug 17, 4:45 PM EDT	Severe Thunderstorm Warning	PHI	Monroe, Northampton	60 min
Aug 17, 4:51 PM EDT	Severe Thunderstorm Warning	PHI	Lehigh, Northampton	43 min
Aug 17, 5:17 PM EDT	Severe Thunderstorm Warning	PHI	Bucks	58 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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.