Alert archive / Pennsylvania / Flash Flood Warnings in 2011

Flash Flood Warning 38, NWS Philadelphia/Mount Holly

August 21, 20114 counties in Pennsylvania; Burlington County, New Jersey

NWS Philadelphia/Mount Holly issued this flash flood warning at Aug 21, 2011, 6:05 PM EDT for 4 counties in Pennsylvania; Burlington County, New Jersey. It was in force for 6 hr. 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: Aug 21, 2011, 6:05 PM EDT (22:05 UTC)
Expired: Aug 22, 2011, 12:00 AM EDT
In force: 6 hr
Issued by: NWS Philadelphia/Mount Holly
Area: Storm-based polygon
Flood severity: None

Counties Burlington County, NJ, Bucks County, PA, Delaware County, PA, Montgomery County, PA, Philadelphia County, PA

The radar

The Philadelphia radar (KDIX), 56 km from the middle of the area, began a volume at 22:09 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
Aug 21, 7:00 PM EDT	FLOOD	Bristol, PA	STREET FLOODING OF A FEW FEET DUE TO POOR DRAINAGE... TIME IS ESTIMATED

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

The nearest sounding before it

Brookhaven, NY (KOKX), launched 12:00Z, 10.1 hours before the alert went out and 203 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: 874 J/kg
Mixed-layer CIN: -29 J/kg
Mixed-layer LCL: 857 m above ground
0-6 km bulk shear: 22 kt
0-1 km storm-relative helicity: 55 m²/s²
0-3 km storm-relative helicity: 116 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.

346 
WGUS51 KPHI 212205
FFWPHI
NJC005-PAC017-045-091-101-220000-
/O.NEW.KPHI.FF.W.0038.110821T2205Z-110822T0000Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
605 PM EDT SUN AUG 21 2011

THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ HAS ISSUED A

* FLASH FLOOD WARNING FOR...
  NORTH CENTRAL DELAWARE COUNTY...
  NORTHERN PHILADELPHIA COUNTY...
  SOUTHEASTERN MONTGOMERY COUNTY...
  SOUTHEASTERN BUCKS COUNTY...
  NORTH CENTRAL BURLINGTON COUNTY...

* UNTIL 800 PM EDT...

* AT 600 PM EDT...CONTINUING RUNOFF FROM PREVIOUS HEAVY
  THUNDERSTORMS...AS WELL AS ONGOING THUNDERSTORMS...OVER NORTH
  CENTRAL BURLINGTON...NORTH CENTRAL DELAWARE...NORTHERN
  PHILADELPHIA...SOUTHEASTERN BUCKS...AND SOUTHEASTERN MONTGOMERY
  COUNTIES.

* LOCATIONS IN THE WARNING INCLUDE BUT ARE NOT LIMITED TO RURAL AREAS
  OF NORTH CENTRAL BURLINGTON...NORTH CENTRAL DELAWARE COUNTY...
  NORTHERN PHILADELPHIA...SOUTHEASTERN BUCKS AND SOUTHEASTERN
  MONTGOMERY COUNTIES.

RUNOFF FROM THIS HEAVY RAIN WILL OCCUR LATE THIS AFTERNOON AND EARLY 
THIS EVENING...AND ANOTHER 1/2 TO 3/4 OF AN INCH OF RAIN MAY OCCUR 
OVER LOWER BUCKS AND NORTHERN BURLINGTON COUNTIES THROUGH 6:30 PM.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

PLEASE REPORT FLOODING...HAIL OR WIND DAMAGE TO THE NATIONAL WEATHER 
SERVICE BY CALLING TOLL FREE...1-877-633-6772.

FLOODING IS OCCURRING OR IS IMMINENT. MOST FLOOD RELATED DEATHS 
OCCUR IN AUTOMOBILES. DO NOT ATTEMPT TO CROSS WATER COVERED 
BRIDGES...DIPS...OR LOW WATER CROSSINGS. TURN AROUND...DON'T DROWN! 
NEVER TRY TO CROSS A FLOWING STREAM...EVEN A SMALL ONE...ON FOOT. TO 
ESCAPE RISING WATER MOVE UP TO HIGHER GROUND.

&&

LAT...LON 4009 7485 4005 7498 4010 7497 4011 7502
      4006 7512 4006 7518 3997 7541 4005 7541
      4007 7537 4007 7540 4011 7540 4026 7488
      4021 7478 4015 7472 4017 7470 4009 7460

$$

3 follow-up statements

186 
WGUS51 KPHI 212343
FFWPHI
NJC005-PAC017-045-091-101-220200-
/O.EXT.KPHI.FF.W.0038.000000T0000Z-110822T0200Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
743 PM EDT SUN AUG 21 2011

THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ HAS EXTENDED THE

* FLASH FLOOD WARNING FOR...
  NORTH CENTRAL DELAWARE COUNTY...
  NORTHERN PHILADELPHIA COUNTY...
  SOUTHEASTERN MONTGOMERY COUNTY...
  SOUTHEASTERN BUCKS COUNTY...
  NORTHWESTERN BURLINGTON COUNTY...

* UNTIL 1000 PM EDT...

* AT 740 PM EDT...FLASH FLOODING FROM PREVIOUS THUNDERSTORMS WAS
  ONGOING...SO THE FLASH FLOOD WARNING HAS BEEN EXTENDED
  OVER EXTREME NORTH CENTRAL DELAWARE...NORTHERN PHILADELPHIA...
  NORTHWESTERN BURLINGTON...SOUTHEASTERN BUCKS AND SOUTHEASTERN
  MONTGOMERY COUNTIES. ADDITIONAL SHOWERS AND THUNDERSTORMS WERE
  LIKELY TO MOVE OVER THE WARNING AREA...AND RUNOFF FROM PREVIOUS
  RAINS WILL CONTINUE. 

* LOCATIONS IN THE WARNING INCLUDE BUT ARE NOT LIMITED TO AREAS OF
  EXTREME NORTH CENTRAL DELAWARE...NORTHERN PHILADELPHIA...
  NORTHWESTERN BURLINGTON...SOUTHEASTERN BUCKS AND SOUTHEASTERN
  MONTGOMERY COUNTIES.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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. NEVER ATTEMPT TO CROSS
SWIFTLY FLOWING WATERS OR WATERS OF UNKNOWN DEPTH BY FOOT OR IN AN
AUTOMOBILE. TURN AROUND DON'T DROWN!

FLOODING IS OCCURRING. MOST FLOOD RELATED DEATHS OCCUR IN 
AUTOMOBILES. DO NOT ATTEMPT TO CROSS WATER COVERED BRIDGES...DIPS... 
OR LOW WATER CROSSINGS. TURN AROUND...DON'T DROWN! NEVER TRY TO 
CROSS A FLOWING STREAM...EVEN A SMALL ONE...ON FOOT. TO ESCAPE 
RISING WATER MOVE UP TO HIGHER GROUND.

&&

LAT...LON 4009 7485 4005 7498 4010 7497 4011 7502
      4006 7512 4006 7518 3997 7541 4005 7541
      4007 7537 4007 7540 4011 7540 4026 7488
      4021 7478 4015 7472 4017 7470 4009 7460

$$

647 
WGUS51 KPHI 220156
FFWPHI
NJC005-PAC017-045-091-101-220400-
/O.EXT.KPHI.FF.W.0038.000000T0000Z-110822T0400Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
956 PM EDT SUN AUG 21 2011

THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ HAS EXTENDED THE

* FLASH FLOOD WARNING FOR...
  NORTH CENTRAL DELAWARE COUNTY...
  NORTHERN PHILADELPHIA COUNTY...
  SOUTHEASTERN MONTGOMERY COUNTY...
  SOUTHEASTERN BUCKS COUNTY...
  NORTHWESTERN BURLINGTON COUNTY...

* UNTIL MIDNIGHT EDT...

* AT 950 PM EDT...SHOWERS AND THUNDERSTORMS WERE ENDING THIS EVENING
  OVER SOUTHEASTERN PENNSYLVANIA AND ADJACENT AREAS OF NEW JERSEY
  BUT HAVE COMBINED WITH THE HIGH RAIN TOTALS OF THIS AFTERNOON TO
  PRODUCE CONTINUING RUNOFF LATE THIS EVENING. WATER LEVELS REMAINED
  HIGH OVER THE WARNING AREA...AND FLOODING WAS STILL REPORTED OVER
  PORTIONS OF LOWER BUCKS COUNTY PENNSYLVANIA. THEREFORE THE FLASH
  FLOOD WARNING WILL BE EXTENDED THROUGH MIDNIGHT TO ALLOW WATER TO
  DRAIN AWAY OVER THE NEXT COUPLE OF HOURS. MOTORISTS ARE URGED TO
  WATCH FOR FLOODED AREAS ON ROADS. NEVER DRIVE INTO OR THROUGH
  FLOODED ROADWAYS.

* LOCATIONS IN THE WARNING INCLUDE BUT ARE NOT LIMITED TO RURAL AREAS
  OF EXTREME NORTH CENTRAL DELAWARE...NORTHERN PHILADELPHIA...
  NORTHWESTERN BURLINGTON...SOUTHEASTERN BUCKS AND SOUTHEASTERN
  MONTGOMERY COUNTIES.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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. NEVER ATTEMPT TO CROSS 
SWIFTLY FLOWING WATERS OR WATERS OF UNKNOWN DEPTH BY FOOT OR IN AN 
AUTOMOBILE. TURN AROUND DON'T DROWN!

BE ESPECIALLY CAUTIOUS AT NIGHT WHEN IT IS HARDER TO RECOGNIZE THE
DANGERS OF FLOODING. IF FLASH FLOODING IS OBSERVED ACT QUICKLY. MOVE
UP TO HIGHER GROUND TO ESCAPE FLOOD WATERS. DO NOT STAY IN AREAS
SUBJECT TO FLOODING WHEN WATER BEGINS RISING.

&&

LAT...LON 4009 7485 4005 7498 4010 7497 4011 7502
      4006 7512 4006 7518 3997 7541 4005 7541
      4007 7537 4007 7540 4011 7540 4026 7488
      4021 7478 4015 7472 4017 7470 4009 7460

$$

023 
WGUS71 KPHI 220357 RRA
FFSPHI

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
1157 PM EDT SUN AUG 21 2011

NJC005-PAC017-045-091-101-220407-
/O.EXP.KPHI.FF.W.0038.000000T0000Z-110822T0400Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
DELAWARE PA-PHILADELPHIA PA-MONTGOMERY PA-BUCKS PA-BURLINGTON NJ-
1157 PM EDT SUN AUG 21 2011

...THE FLASH FLOOD WARNING WILL EXPIRE AT MIDNIGHT EDT FOR
NORTHWESTERN BURLINGTON...SOUTHEASTERN BUCKS...SOUTHEASTERN
MONTGOMERY...NORTHERN PHILADELPHIA AND NORTH CENTRAL DELAWARE
COUNTIES...

THE WATERS FROM THE EARLIER HEAVY RAINS ARE RECEDING AND NO LONGER
POSE A THREAT TO LIFE OR PROPERTY. THEREFORE...THE FLASH FLOOD
WARNING WILL BE ALLOWED TO EXPIRE.

LOCATIONS IN THE WARNING INCLUDE BUT ARE NOT LIMITED TO RURAL AREAS
OF EXTREME NORTH CENTRAL DELAWARE...NORTHERN PHILADELPHIA...
NORTHWESTERN BURLINGTON...SOUTHEASTERN BUCKS AND SOUTHEASTERN
MONTGOMERY COUNTIES.

LAT...LON 4009 7485 4005 7498 4010 7497 4011 7502
      4006 7512 4006 7518 3997 7541 4005 7541
      4007 7537 4007 7540 4011 7540 4026 7488
      4021 7478 4015 7472 4017 7470 4009 7460

$$

HAYES

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 21, 3:28 AM EDT	Flash Flood Watch	PHI	Delaware, Philadelphia	17 hr
Aug 21, 1:11 PM EDT	Special Weather Statement	PHI	Montgomery	64 min
Aug 21, 1:25 PM EDT	Areal Flood Advisory	PHI	Bucks, Chester, Montgomery	110 min
Aug 21, 1:47 PM EDT	Severe Thunderstorm Warning	PHI	Bucks, Chester, Delaware, Montgomery, Philadelphia	58 min
Aug 21, 2:33 PM EDT	Areal Flood Advisory	PHI	Bucks, Delaware, Montgomery, Philadelphia	117 min
Aug 21, 2:43 PM EDT	Severe Thunderstorm Warning	PHI	Bucks, Chester, Delaware, Montgomery, Philadelphia	62 min
Aug 21, 3:31 PM EDT	Flash Flood Warning	PHI	Philadelphia	8 hr
Aug 21, 4:11 PM EDT	Special Weather Statement	PHI	Carbon, Monroe	64 min
Aug 21, 4:19 PM EDT	Areal Flood Advisory	PHI	Carbon, Monroe	3 hr
Aug 21, 4:35 PM EDT	Areal Flood Advisory	PHI	Berks, Bucks, Chester, Delaware, Lehigh, Montgomery and 2 more	3 hr
Aug 21, 4:53 PM EDT	Special Weather Statement	PHI	Lehigh, Northampton	67 min
Aug 21, 6:41 PM EDT	Special Weather Statement	PHI	Berks	64 min
Aug 21, 7:35 PM EDT	Areal Flood Advisory	PHI	Berks, Bucks, Chester, Delaware, Montgomery, Philadelphia	115 min
Aug 21, 3:24 AM EDT	Small Craft Advisory	PHI		30 hr
Aug 21, 8:41 AM EDT	Special Weather Statement	PHI	Salem	64 min
Aug 21, 10:33 AM EDT	Special Marine Warning	PHI		57 min
Aug 21, 11:07 AM EDT	Special Marine Warning	PHI		83 min
Aug 21, 12:20 PM EDT	Special Weather Statement	PHI	Morris	55 min
Aug 21, 12:33 PM EDT	Severe Thunderstorm Warning	PHI	Morris	33 min
Aug 21, 12:39 PM EDT	Special Weather Statement	PHI	Burlington, Camden	66 min
Aug 21, 3:08 PM EDT	Severe Thunderstorm Warning	PHI	Burlington, Mercer, Middlesex, Monmouth, Ocean	67 min
Aug 21, 3:21 PM EDT	Severe Thunderstorm Warning	PHI	Monmouth, Ocean	54 min
Aug 21, 3:22 PM EDT	Special Marine Warning	PHI		83 min
Aug 21, 3:46 PM EDT	Flash Flood Warning	PHI	Burlington	2 hr
Aug 21, 4:14 PM EDT	Severe Thunderstorm Warning	PHI	Monmouth, Ocean	46 min
Aug 21, 4:26 PM EDT	Special Marine Warning	PHI		57 min
Aug 21, 5:44 PM EDT	Special Weather Statement	PHI	Mercer	61 min
Aug 21, 6:12 PM EDT	Severe Thunderstorm Warning	PHI	Burlington, Mercer, Middlesex, Monmouth, Ocean	63 min
Aug 21, 6:20 PM EDT	Special Weather Statement	PHI	Hunterdon	55 min
Aug 21, 6:54 PM EDT	Areal Flood Advisory	PHI	Hunterdon, Middlesex, Morris, Somerset, Sussex, Warren	111 min
Aug 21, 7:08 PM EDT	Special Weather Statement	PHI	Hunterdon, Middlesex, Somerset	52 min
Aug 21, 7:18 PM EDT	Severe Thunderstorm Warning	PHI	Monmouth, Ocean	42 min
Aug 21, 7:21 PM EDT	Special Marine Warning	PHI		84 min
Aug 21, 7:24 PM EDT	Flash Flood Warning	PHI	Mercer, Monmouth, Ocean	5 hr

Nearby

Flash Flood Warnings in Pennsylvania, 2011 Flash Flood Warnings in New Jersey, 2011 Every flash flood 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; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.