Alert archive / Pennsylvania / Flash Flood Warnings in 2009

Flash Flood Warning 4, NWS Philadelphia/Mount Holly

June 9, 2009Chester County, Pennsylvania

NWS Philadelphia/Mount Holly issued this flash flood warning at Jun 9, 2009, 9:56 AM EDT for Chester County, Pennsylvania. It was in force for 105 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: Jun 9, 2009, 9:56 AM EDT (13:56 UTC)
Expired: Jun 9, 2009, 11:41 AM EDT
In force: 105 min
Issued by: NWS Philadelphia/Mount Holly
Area: Storm-based polygon
Flood severity: None

County Chester County, PA

The radar

The Philadelphia radar (KDIX), 108 km from the middle of the area, began a volume at 13:57 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 nearest sounding before it

Phillips Aaf/Abe, MD (KAPG), launched 12:00Z, 1.9 hours before the alert went out and 73 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: 1272 J/kg
Mixed-layer CIN: -67 J/kg
Mixed-layer LCL: 804 m above ground
0-6 km bulk shear: 28 kt
0-1 km storm-relative helicity: 87 m²/s²
0-3 km storm-relative helicity: 108 m²/s²
Significant tornado parameter: 0.3
Supercell composite: 1.9

Open this sounding in Storm Lab

The text

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

000 
WGUS51 KPHI 091356
FFWPHI
PAC029-091800-
/O.NEW.KPHI.FF.W.0004.090609T1356Z-090609T1800Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
956 AM EDT TUE JUN 9 2009

THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ HAS ISSUED A

* FLASH FLOOD WARNING FOR...
  CENTRAL CHESTER COUNTY IN SOUTHEAST PENNSYLVANIA...
  THIS INCLUDES THE CITY OF WEST CHESTER...

* UNTIL 200 PM EDT

* AT 945 AM EDT...FLASH FLOODING WAS REPORTED FROM A THUNDERSTORM
  OVER THE WARNED AREA.

* LOCATIONS IN THE WARNING INCLUDE BUT ARE NOT LIMITED TO
  GLENMOORE...PAOLI AND LIONVILLE

PRECAUTIONARY/PREPAREDNESS ACTIONS...

EXCESSIVE RUNOFF FROM HEAVY RAINFALL WILL CAUSE FLOODING OF SMALL
CREEKS AND STREAMS...COUNTRY ROADS...AS WELL AS FARMLAND ALONG THE
BANKS OF CREEKS AND STREAMS.

DO NOT DRIVE YOUR VEHICLE INTO AREAS WHERE THE WATER COVERS THE
ROADWAY. THE WATER DEPTH MAY BE TOO GREAT TO ALLOW YOUR CAR TO CROSS
SAFELY. MOVE TO HIGHER GROUND.

MOST FLOOD DEATHS OCCUR IN AUTOMOBILES. NEVER DRIVE YOUR VEHICLE INTO
AREAS WHERE THE WATER COVERS THE ROADWAY. FLOOD WATERS ARE USUALLY
DEEPER THAN THEY APPEAR. JUST ONE FOOT OF FLOWING WATER IS POWERFUL
ENOUGH TO SWEEP VEHICLES OFF THE ROAD. WHEN ENCOUNTERING FLOODED
ROADS MAKE THE SMART CHOICE...TURN AROUND...DONT DROWN.

A FLASH FLOOD WARNING MEANS THAT FLOODING IS IMMINENT OR OCCURRING.
IF YOU ARE IN THE WARNING AREA MOVE TO HIGHER GROUND IMMEDIATELY.
RESIDENTS LIVING ALONG STREAMS AND CREEKS SHOULD TAKE IMMEDIATE
PRECAUTIONS TO PROTECT LIFE AND PROPERTY. DO NOT ATTEMPT TO CROSS
SWIFTLY FLOWING WATERS OR WATERS OF UNKNOWN DEPTH BY FOOT OR BY
AUTOMOBILE.

&&

LAT...LON 4002 7585 4011 7582 4015 7578 4010 7567
      4008 7558 4012 7551 4006 7544 3996 7551
      3992 7558 3993 7562 3998 7565 3997 7582

$$

KRUZDLO

1 follow-up statement

000 
WGUS71 KPHI 091541
FFSPHI

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
1141 AM EDT TUE JUN 9 2009

PAC029-091551-
/O.CAN.KPHI.FF.W.0004.000000T0000Z-090609T1800Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
CHESTER PA-
1141 AM EDT TUE JUN 9 2009

...THE FLASH FLOOD WARNING HAS BEEN CANCELLED FOR CENTRAL CHESTER
COUNTY...

LAT...LON 4002 7585 4011 7582 4015 7578 4010 7567
      4008 7558 4012 7551 4006 7544 3996 7551
      3992 7558 3993 7562 3998 7565 3997 7582

$$

AMC

The office that day

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

Issued	Product	Office	Counties	Lasted
Jun 9, 4:17 AM EDT	Dense Fog Advisory	PHI		5 hr
Jun 9, 5:38 AM EDT	Severe Thunderstorm Warning	PHI	Berks	67 min
Jun 9, 7:20 AM EDT	Severe Thunderstorm Warning	PHI	Chester, Delaware, Montgomery, Philadelphia	55 min
Jun 9, 8:00 AM EDT	Severe Thunderstorm Warning	PHI	Delaware, Philadelphia	60 min
Jun 9, 8:06 AM EDT	Severe Thunderstorm Warning	PHI	Philadelphia	54 min
Jun 9, 8:20 AM EDT	Areal Flood Advisory	PHI	Delaware, Montgomery, Philadelphia	3 hr
Jun 9, 8:42 AM EDT	Areal Flood Advisory	PHI	Bucks	3 hr
Jun 9, 1:49 PM EDT	Flash Flood Watch	PHI	Delaware, Philadelphia	5 hr
Jun 9, 2:20 PM EDT	Flash Flood Warning	PHI	Berks, Chester	3 hr
Jun 9, 2:24 PM EDT	Severe Thunderstorm Warning	PHI	Berks, Chester, Montgomery	66 min
Jun 9, 2:59 PM EDT	Tornado Warning	PHI	Chester	32 min
Jun 9, 3:08 PM EDT	Tornado Warning	PHI	Chester	28 min
Jun 9, 3:14 PM EDT	Tornado Warning	PHI	Chester	46 min
Jun 9, 3:29 PM EDT	Severe Thunderstorm Warning	PHI	Chester	61 min

Nearby

Flash Flood Warnings in Pennsylvania, 2009 Every flash flood 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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.