Alert archive / Pennsylvania / Severe Thunderstorm Warnings in 2009

Severe Thunderstorm Warning 113, NWS Philadelphia/Mount Holly

June 30, 2009Bucks County, Montgomery County, Pennsylvania

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Jun 30, 2009, 2:51 PM EDT for Bucks County, Montgomery County, Pennsylvania. It was in force for 54 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 30, 2009, 2:51 PM EDT (18:51 UTC)
Expired: Jun 30, 2009, 3:45 PM EDT
In force: 54 min
Issued by: NWS Philadelphia/Mount Holly
Area: Storm-based polygon

Counties Bucks County, PA, Montgomery County, PA

The radar

The Philadelphia radar (KDIX), 83 km from the middle of the area, began a volume at 18:53 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 30, 2:57 PM EDT	TSTM WND DMG	7 Nw Fricks, PA	80 FOOT TREE KNOCKED DOWN.
Jun 30, 3:36 PM EDT	TSTM WND DMG	5 Sw Washington Crossin, PA	TREES DOWN IN NEWTOWN BOROUGH

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 30, 11:37 AM EDT	Severe Thunderstorm Watch	SPC	7 hr

The nearest sounding before it

Phillips Aaf/Abe, MD (KAPG), launched 12:00Z, 6.9 hours before the alert went out and 129 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: 161 J/kg
Mixed-layer CIN: -86 J/kg
Mixed-layer LCL: 1704 m above ground
0-6 km bulk shear: 51 kt
0-1 km storm-relative helicity: 53 m²/s²
0-3 km storm-relative helicity: 95 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.8

Open this sounding in Storm Lab

The text

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

000 
WUUS51 KPHI 301851
SVRPHI
PAC017-091-301945-
/O.NEW.KPHI.SV.W.0113.090630T1851Z-090630T1945Z/

BULLETIN - EAS ACTIVATION REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
251 PM EDT TUE JUN 30 2009

THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ HAS ISSUED A

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

* UNTIL 345 PM EDT

* AT 250 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
  SOUDERTON...OR 19 MILES SOUTH OF ALLENTOWN...AND MOVING NORTHEAST
  AT 20 MPH.

* THE SEVERE THUNDERSTORM WILL BE NEAR...
  PERKASIE AROUND 305 PM EDT...
  QUAKERTOWN AROUND 310 PM EDT...
  DUBLIN AROUND 320 PM EDT...
  BEDMINSTER AROUND 330 PM EDT...
  PIPERSVILLE AROUND 335 PM EDT...
  OTTSVILLE AND TINICUM AROUND 340 PM EDT...

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A SEVERE THUNDERSTORM WATCH REMAINS IN EFFECT UNTIL 700 PM EDT
TUESDAY EVENING FOR NORTHWESTERN NEW JERSEY AND EASTERN PENNSYLVANIA.

&&

LAT...LON 4006 7532 4028 7553 4043 7545 4048 7540
      4058 7520 4054 7519 4055 7514 4054 7509
      4050 7506 4042 7506 4040 7502 4041 7500
      4024 7487
TIME...MOT...LOC 1851Z 229DEG 16KT 4033 7537

$$

NIERENBERG

The office that day

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

Issued	Product	Office	Counties	Lasted
Jun 30, 1:15 PM EDT	Severe Thunderstorm Warning	PHI	Berks	75 min
Jun 30, 2:31 PM EDT	Severe Thunderstorm Warning	PHI	Berks, Chester, Montgomery	44 min
Jun 30, 3:12 PM EDT	Severe Thunderstorm Warning	PHI	Bucks	63 min
Jun 30, 3:13 PM EDT	Flash Flood Warning	PHI	Bucks, Montgomery	114 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.