Alert archive / Pennsylvania / Severe Thunderstorm Warnings in 2011

Severe Thunderstorm Warning 298, NWS Philadelphia/Mount Holly

September 11, 2011Bucks County, Montgomery County, Pennsylvania

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Sep 11, 2011, 9:54 PM EDT for Bucks County, Montgomery County, Pennsylvania. It was in force for 51 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: Sep 11, 2011, 9:54 PM EDT (01:54 UTC)
Expired: Sep 11, 2011, 10:45 PM EDT
In force: 51 min
Issued by: NWS Philadelphia/Mount Holly
Area: Storm-based polygon

Counties Bucks County, PA, Montgomery County, PA

The radar

The Philadelphia radar (KDIX), 99 km from the middle of the area, began a volume at 01:56 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 nearest sounding before it

Washington/Dulle, VA (KIAD), launched 00:00Z, 1.9 hours before the alert went out and 216 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: 420 J/kg
Mixed-layer CIN: -58 J/kg
Mixed-layer LCL: 1369 m above ground
0-6 km bulk shear: 36 kt
0-1 km storm-relative helicity: 144 m²/s²
0-3 km storm-relative helicity: 126 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.

473 
WUUS51 KPHI 120154
SVRPHI
PAC017-091-120245-
/O.NEW.KPHI.SV.W.0298.110912T0154Z-110912T0245Z/

BULLETIN - EAS ACTIVATION REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
954 PM EDT SUN SEP 11 2011

THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ HAS ISSUED A

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

* UNTIL 1045 PM EDT

* AT 952 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 19 MILES
  EAST OF READING...AND MOVING EAST AT 15 MPH.

* THE SEVERE THUNDERSTORM WILL BE NEAR...
  ROYERSFORD AROUND 1005 PM EDT...
  6 MILES SOUTH OF GREEN LANE AROUND 1010 PM EDT...
  SCHWENKSVILLE...SPRING MOUNT AND TRAPPE AROUND 1015 PM EDT...
  COLLEGEVILLE AROUND 1020 PM EDT...
  SOUDERTON AROUND 1040 PM EDT...
  LANSDALE AND HATFIELD AROUND 1045 PM EDT...

PRECAUTIONARY/PREPAREDNESS ACTIONS...

IN ADDITION TO DAMAGING WINDS...DANGEROUS CLOUD TO GROUND LIGHTNING 
IS OCCURRING WITH THIS STORM. MOVE INDOORS IMMEDIATELY! LIGHTNING IS 
ONE OF NATURES GREATEST KILLERS. REMEMBER...IF YOU CAN HEAR 
THUNDER...YOU ARE CLOSE ENOUGH TO BE STRUCK BY LIGHTNING.

PLEASE REPORT HAIL OR STRONG WINDS TO THE NATIONAL WEATHER SERVICE BY
CALLING TOLL FREE...1-877-633-6772...WHEN YOU CAN DO SO SAFELY.

&&

LAT...LON 4042 7556 4037 7516 4006 7529 4013 7551
      4015 7551 4015 7554 4020 7557 4020 7559
      4022 7559 4024 7564 4026 7567
TIME...MOT...LOC 0154Z 282DEG 13KT 4027 7556

$$

MPD

1 follow-up statement

416 
WWUS51 KPHI 120217
SVSPHI

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
1017 PM EDT SUN SEP 11 2011

PAC017-091-120245-
/O.CON.KPHI.SV.W.0298.000000T0000Z-110912T0245Z/
MONTGOMERY PA-BUCKS PA-
1017 PM EDT SUN SEP 11 2011

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 1045 PM EDT
FOR WEST CENTRAL BUCKS AND CENTRAL MONTGOMERY COUNTIES...

AT 1013 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR CONTINUED TO
INDICATE A SEVERE THUNDERSTORM CAPABLE OF PRODUCING DAMAGING WINDS IN
EXCESS OF 60 MPH.  THIS STORM WAS LOCATED NEAR SCHWENKSVILLE...OR 22
MILES NORTH OF WEST CHESTER...MOVING EAST AT 15 MPH.

THE SEVERE THUNDERSTORM WILL BE NEAR...
  EVANSBURG BY 1025 PM EDT...
  SKIPPACK...HARLEYSVILLE AND 6 MILES NORTH OF EAGLEVILLE BY 1030 PM
  EDT...
  KULPSVILLE AND SOUDERTON BY 1040 PM EDT...
  LANSDALE...NORTH WALES...HATFIELD AND MONTGOMERYVILLE BY 1045 PM
  EDT...

PRECAUTIONARY/PREPAREDNESS ACTIONS...

IN ADDITION TO DAMAGING WINDS...DANGEROUS 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.

PLEASE REPORT HAIL OR STRONG WINDS TO THE NATIONAL WEATHER SERVICE BY
CALLING TOLL FREE...1-877-633-6772...WHEN YOU CAN DO SO SAFELY.

&&

LAT...LON 4024 7554 4027 7555 4039 7547 4037 7516
      4006 7529 4012 7548 4013 7548 4013 7551
      4016 7551 4015 7554 4021 7557
TIME...MOT...LOC 0217Z 282DEG 13KT 4025 7545

$$

MPD

The office that day

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

Issued	Product	Office	Counties	Lasted
Sep 11, 8:19 PM EDT	Flash Flood Warning	PHI	Berks	3 hr
Sep 11, 8:46 PM EDT	Areal Flood Advisory	PHI	Chester	3 hr
Sep 11, 9:00 PM EDT	Flash Flood Warning	PHI	Chester	3 hr
Sep 11, 9:14 PM EDT	Flash Flood Warning	PHI	Berks, Chester, Montgomery	110 min
Sep 11, 9:14 PM EDT	Special Weather Statement	PHI	Berks, Chester, Lehigh, Montgomery	61 min
Sep 11, 9:24 PM EDT	Severe Thunderstorm Warning	PHI	Chester	51 min
Sep 11, 9:34 PM EDT	Special Weather Statement	PHI	Philadelphia	41 min
Sep 11, 9:56 PM EDT	Flash Flood Warning	PHI	Bucks, Chester, Delaware, Montgomery, Philadelphia	4 hr
Sep 11, 10:25 PM EDT	Special Weather Statement	PHI	Philadelphia	65 min
Sep 11, 10:29 PM EDT	Severe Thunderstorm Warning	PHI	Chester, Delaware	46 min
Sep 11, 10:44 PM EDT	Areal Flood Advisory	PHI	Chester	107 min
Sep 11, 10:52 PM EDT	Special Weather Statement	PHI	Bucks, Delaware, Montgomery, Philadelphia	83 min
Sep 11, 11:10 PM EDT	Severe Thunderstorm Warning	PHI	Chester, Delaware, Philadelphia	65 min
Sep 12, 11:05 AM EDT	Coastal Flood Statement	PHI	Delaware, Philadelphia	6 hr

Nearby

Severe Thunderstorm Warnings in Pennsylvania, 2011 Every severe thunderstorm warning in 2011

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.