Alert archive / New Jersey / Flash Flood Watches in 2011

Flash Flood Watch 8, NWS Philadelphia/Mount Holly

August 21, 20114 states

NWS Philadelphia/Mount Holly issued this flash flood watch at Aug 21, 2011, 3:28 AM EDT for 4 states. It took effect at Aug 21, 2011, 2:00 PM EDT. It was in force for 7 hr.

The area

The counties it named.

The facts

Issued
Aug 21, 2011, 3:28 AM EDT (07:28 UTC)
In effect from
Aug 21, 2011, 2:00 PM EDT
Expired
Aug 21, 2011, 8:48 PM EDT
In force
7 hr
Issued by
NWS Philadelphia/Mount Holly
Flood severity
None

Counties New Castle County, DE, Cecil County, MD, Kent County, MD, Burlington County, NJ, Camden County, NJ, Cumberland County, NJ, Gloucester County, NJ, Hunterdon County, NJ, Mercer County, NJ, Middlesex County, NJ, Morris County, NJ, Salem County, NJ, Somerset County, NJ, Sussex County, NJ, Warren County, NJ, Delaware County, PA, Philadelphia County, PA

The radar

The Philadelphia radar (KDIX), 59 km from the middle of the area, began a volume at 07:27 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

Brookhaven, NY (KOKX), launched 00:00Z, 7.5 hours before the alert went out and 207 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-pSkew-T log-p diagram, Brookhaven, NY at 00:00Z on 2011-08-21Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 122 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Brookhaven, NY at 00:00Z on 2011-08-21The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 39 square meters per square second.1939Sfc1 km3 km6 km9 kmRMLM
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
122 J/kg
Mixed-layer CIN
-64 J/kg
Mixed-layer LCL
1157 m above ground
0-6 km bulk shear
11 kt
0-1 km storm-relative helicity
39 m²/s²
0-3 km storm-relative helicity
41 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.

877 
WGUS61 KPHI 210728
FFAPHI

URGENT - IMMEDIATE BROADCAST REQUESTED
FLOOD WATCH
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
328 AM EDT SUN AUG 21 2011

NJZ001-007>010-012-212100-
/O.NEW.KPHI.FF.A.0008.110821T1800Z-110822T0600Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
SUSSEX-WARREN-MORRIS-HUNTERDON-SOMERSET-MIDDLESEX-
INCLUDING THE CITIES OF...NEWTON...WASHINGTON...MORRISTOWN...
FLEMINGTON...SOMERVILLE...NEW BRUNSWICK
328 AM EDT SUN AUG 21 2011

...FLASH FLOOD WATCH IN EFFECT FROM 2 PM EDT THIS AFTERNOON
THROUGH LATE TONIGHT...

THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY HAS ISSUED A

* FLASH FLOOD WATCH FOR PORTIONS OF NORTHERN NEW JERSEY AND 
  NORTHWEST NEW JERSEY...INCLUDING THE FOLLOWING AREAS...IN 
  NORTHERN NEW JERSEY...MIDDLESEX...MORRIS...SOMERSET...SUSSEX 
  AND WARREN. IN NORTHWEST NEW JERSEY...HUNTERDON. 

* FROM 2 PM EDT THIS AFTERNOON THROUGH LATE TONIGHT

* SHOWERS AND THUNDERSTORMS DEVELOPING AHEAD OF A STRONG COLD
  FRONT ARE EXPECTED TO PRODUCE LOCALLY HEAVY RAINFALL THIS
  AFTERNOON AND TONIGHT. THE RECENT RAINFALL HAS LEFT THE WATCH
  AREA VULNERABLE TO HEAVY RAINFALL...AND ANY ADDITIONAL HEAVY
  RAIN MAY LEAD TO LOCALIZED FLASH FLOODING.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A FLASH FLOOD WATCH MEANS THAT CONDITIONS MAY DEVELOP THAT LEAD
TO FLASH FLOODING. FLASH FLOODING IS A VERY DANGEROUS SITUATION.

YOU SHOULD MONITOR LATER FORECASTS AND BE PREPARED TO TAKE ACTION
SHOULD FLASH FLOOD WARNINGS BE ISSUED.

&&

$$
3 follow-up statements
123 
WGUS61 KPHI 211524
FFAPHI

URGENT - IMMEDIATE BROADCAST REQUESTED
FLOOD WATCH
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
1124 AM EDT SUN AUG 21 2011

DEZ001-MDZ008-012-NJZ015>019-021-PAZ067>071-212200-
/O.EXA.KPHI.FF.A.0008.110821T1800Z-110822T0600Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
NEW CASTLE-CECIL-KENT MD-MERCER-SALEM-GLOUCESTER-CAMDEN-
NORTHWESTERN BURLINGTON-CUMBERLAND-CHESTER-MONTGOMERY-BUCKS-
DELAWARE-PHILADELPHIA-
INCLUDING THE CITIES OF...WILMINGTON...ELKTON...CHESTERTOWN...
TRENTON...PENNSVILLE...GLASSBORO...CAMDEN...CHERRY HILL...
MOORESTOWN...MOUNT HOLLY...MILLVILLE...WEST CHESTER...
NORRISTOWN...DOYLESTOWN...MEDIA...PHILADELPHIA
1124 AM EDT SUN AUG 21 2011

...FLASH FLOOD WATCH IN EFFECT THROUGH LATE TONIGHT...

THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY HAS EXPANDED THE

* FLASH FLOOD WATCH TO INCLUDE PORTIONS OF NORTHERN DELAWARE...
  NORTHEAST MARYLAND...NEW JERSEY AND SOUTHEAST PENNSYLVANIA...
  INCLUDING THE FOLLOWING AREAS...IN NORTHERN DELAWARE...NEW
  CASTLE. IN NORTHEAST MARYLAND...CECIL AND KENT MD. IN NEW
  JERSEY...CAMDEN...CUMBERLAND...GLOUCESTER...MERCER...
  NORTHWESTERN BURLINGTON AND SALEM. IN SOUTHEAST PENNSYLVANIA...
  BUCKS...CHESTER...DELAWARE...MONTGOMERY AND PHILADELPHIA.

* THROUGH LATE TONIGHT.

* SEVERAL ROUNDS OF SHOWERS AND THUNDERSTORMS DURING THE PAST WEEK
  OR SO HAVE SATURATED THE GROUND IN THE WATCH AREA. ADDITIONAL
  DOWNPOURS CAN BE EXPECTED FROM THUNDERSTORMS INTO TONIGHT. THIS MAY
  LEAD TO FLASH FLOODING.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A FLASH FLOOD WATCH MEANS THAT CONDITIONS MAY DEVELOP THAT LEAD
TO FLASH FLOODING. FLASH FLOODING IS A VERY DANGEROUS SITUATION.

YOU SHOULD MONITOR LATER FORECASTS AND BE PREPARED TO TAKE ACTION
SHOULD FLASH FLOOD WARNINGS BE ISSUED.

&&

$$

NJZ001-007>010-012-212200-
/O.CON.KPHI.FF.A.0008.110821T1800Z-110822T0600Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
SUSSEX-WARREN-MORRIS-HUNTERDON-SOMERSET-MIDDLESEX-
INCLUDING THE CITIES OF...NEWTON...WASHINGTON...MORRISTOWN...
FLEMINGTON...SOMERVILLE...NEW BRUNSWICK
1124 AM EDT SUN AUG 21 2011

...FLASH FLOOD WATCH REMAINS IN EFFECT THROUGH LATE TONIGHT...

THE FLASH FLOOD WATCH CONTINUES FOR

* PORTIONS OF NORTHERN NEW JERSEY AND NORTHWEST NEW JERSEY... 
  INCLUDING THE FOLLOWING AREAS...IN NORTHERN NEW JERSEY... 
  MIDDLESEX...MORRIS...SOMERSET...SUSSEX AND WARREN. IN 
  NORTHWEST NEW JERSEY...HUNTERDON. 

* THROUGH LATE TONIGHT

* SEVERAL ROUNDS OF SHOWERS AND THUNDERSTORMS DURING THE PAST WEEK
  OR SO HAVE SATURATED THE GROUND IN THE WATCH AREA. ADDITIONAL
  DOWNPOURS CAN BE EXPECTED FROM THUNDERSTORMS INTO TONIGHT. THIS MAY
  LEAD TO FLASH FLOODING.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A FLASH FLOOD WATCH MEANS THAT CONDITIONS MAY DEVELOP THAT LEAD
TO FLASH FLOODING. FLASH FLOODING IS A VERY DANGEROUS SITUATION.

YOU SHOULD MONITOR LATER FORECASTS AND BE PREPARED TO TAKE ACTION
SHOULD FLASH FLOOD WARNINGS BE ISSUED.

&&

$$

GORSE
237 
WGUS61 KPHI 212005
FFAPHI

FLOOD WATCH
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
405 PM EDT SUN AUG 21 2011

DEZ001-MDZ008-012-NJZ001-007>010-012-015>019-021-PAZ067>071-
220600-
/O.CON.KPHI.FF.A.0008.000000T0000Z-110822T0600Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
NEW CASTLE-CECIL-KENT MD-SUSSEX-WARREN-MORRIS-HUNTERDON-SOMERSET-
MIDDLESEX-MERCER-SALEM-GLOUCESTER-CAMDEN-NORTHWESTERN BURLINGTON-
CUMBERLAND-CHESTER-MONTGOMERY-BUCKS-DELAWARE-PHILADELPHIA-
INCLUDING THE CITIES OF...WILMINGTON...ELKTON...CHESTERTOWN...
NEWTON...WASHINGTON...MORRISTOWN...FLEMINGTON...SOMERVILLE...
NEW BRUNSWICK...TRENTON...PENNSVILLE...GLASSBORO...CAMDEN...
CHERRY HILL...MOORESTOWN...MOUNT HOLLY...MILLVILLE...
WEST CHESTER...NORRISTOWN...DOYLESTOWN...MEDIA...PHILADELPHIA
405 PM EDT SUN AUG 21 2011

...FLASH FLOOD WATCH REMAINS IN EFFECT UNTIL 2 AM EDT MONDAY...

THE FLASH FLOOD WATCH CONTINUES FOR

* PORTIONS OF NORTHERN DELAWARE...NORTHEAST MARYLAND...NEW 
  JERSEY AND SOUTHEAST PENNSYLVANIA...INCLUDING THE FOLLOWING 
  AREAS...IN NORTHERN DELAWARE...NEW CASTLE. IN NORTHEAST 
  MARYLAND...CECIL AND KENT MD. IN NEW JERSEY...CAMDEN... 
  CUMBERLAND...GLOUCESTER...HUNTERDON...MERCER...MIDDLESEX... 
  MORRIS...NORTHWESTERN BURLINGTON...SALEM...SOMERSET...SUSSEX 
  AND WARREN. IN SOUTHEAST PENNSYLVANIA...BUCKS...CHESTER... 
  DELAWARE...MONTGOMERY AND PHILADELPHIA. 

* UNTIL 2 AM EDT MONDAY.

* SEVERAL ROUNDS OF SHOWERS AND THUNDERSTORMS DURING THE PAST WEEK
  OR SO HAVE SATURATED THE GROUND IN THE WATCH AREA. ADDITIONAL
  SHOWERS AND STORMS THROUGH THIS EVENING WILL LOCALLY PRODUCE
  RAINFALL RATES OF 1 TO 2 INCHES PER HOUR. THIS MAY LEAD TO FLASH
  FLOODING.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A FLASH FLOOD WATCH MEANS THAT CONDITIONS MAY DEVELOP THAT LEAD
TO FLASH FLOODING. FLASH FLOODING IS A VERY DANGEROUS SITUATION.

YOU SHOULD MONITOR LATER FORECASTS AND BE PREPARED TO TAKE ACTION
SHOULD FLASH FLOOD WARNINGS BE ISSUED.

&&

$$

GORSE
382 
WGUS61 KPHI 220048
FFAPHI

FLOOD WATCH
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
848 PM EDT SUN AUG 21 2011

DEZ001-MDZ008-012-NJZ001-007>010-012-015>019-021-PAZ067>071-
220200-
/O.CAN.KPHI.FF.A.0008.000000T0000Z-110822T0600Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
NEW CASTLE-CECIL-KENT MD-SUSSEX-WARREN-MORRIS-HUNTERDON-SOMERSET-
MIDDLESEX-MERCER-SALEM-GLOUCESTER-CAMDEN-NORTHWESTERN BURLINGTON-
CUMBERLAND-CHESTER-MONTGOMERY-BUCKS-DELAWARE-PHILADELPHIA-
INCLUDING THE CITIES OF...WILMINGTON...ELKTON...CHESTERTOWN...
NEWTON...WASHINGTON...MORRISTOWN...FLEMINGTON...SOMERVILLE...
NEW BRUNSWICK...TRENTON...PENNSVILLE...GLASSBORO...CAMDEN...
CHERRY HILL...MOORESTOWN...MOUNT HOLLY...MILLVILLE...
WEST CHESTER...NORRISTOWN...DOYLESTOWN...MEDIA...PHILADELPHIA
848 PM EDT SUN AUG 21 2011

...FLASH FLOOD WATCH IS CANCELLED...

THE FLASH FLOOD WATCH FOR PORTIONS OF NORTHERN DELAWARE...
NORTHEAST MARYLAND...NEW JERSEY AND SOUTHEAST PENNSYLVANIA HAS
BEEN CANCELLED. 

SOME SHOWERS AND THUNDERSTORMS WILL LINGER FOR AWHILE TONIGHT,
HOWEVER THE DURATION AND INTENSITY ARE EXPECTED TO BE LESS.
THEREFORE, THE FLASH FLOOD WATCH HAS BEEN CANCELLED.

$$

GORSE

The office that day

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

IssuedProductOfficeCountiesLasted
Aug 21, 3:24 AM EDTSmall Craft AdvisoryPHI30 hr
Aug 21, 8:41 AM EDTSpecial Weather StatementPHISalem64 min
Aug 21, 10:33 AM EDTSpecial Marine WarningPHI57 min
Aug 21, 11:07 AM EDTSpecial Marine WarningPHI83 min
Aug 21, 12:20 PM EDTSpecial Weather StatementPHIMorris55 min
Aug 21, 12:33 PM EDTSevere Thunderstorm WarningPHIMorris33 min
Aug 21, 12:39 PM EDTSpecial Weather StatementPHIBurlington, Camden66 min
Aug 21, 1:47 PM EDTSevere Thunderstorm WarningPHIBurlington, Camden, Mercer58 min
Aug 21, 2:33 PM EDTAreal Flood AdvisoryPHIBurlington, Camden, Mercer117 min
Aug 21, 2:43 PM EDTSevere Thunderstorm WarningPHIBurlington, Camden, Gloucester, Mercer62 min
Aug 21, 3:08 PM EDTSevere Thunderstorm WarningPHIBurlington, Mercer, Middlesex, Monmouth, Ocean67 min
Aug 21, 3:21 PM EDTSevere Thunderstorm WarningPHIMonmouth, Ocean54 min
Aug 21, 3:22 PM EDTSpecial Marine WarningPHI83 min
Aug 21, 3:46 PM EDTFlash Flood WarningPHIBurlington2 hr
Aug 21, 4:14 PM EDTSevere Thunderstorm WarningPHIMonmouth, Ocean46 min
Aug 21, 4:26 PM EDTSpecial Marine WarningPHI57 min
Aug 21, 4:35 PM EDTAreal Flood AdvisoryPHIBurlington, Camden, Mercer, Middlesex, Monmouth, Ocean3 hr
Aug 21, 5:44 PM EDTSpecial Weather StatementPHIMercer61 min
Aug 21, 6:05 PM EDTFlash Flood WarningPHIBurlington6 hr
Aug 21, 6:12 PM EDTSevere Thunderstorm WarningPHIBurlington, Mercer, Middlesex, Monmouth, Ocean63 min
Aug 21, 6:20 PM EDTSpecial Weather StatementPHIHunterdon55 min
Aug 21, 6:54 PM EDTAreal Flood AdvisoryPHIHunterdon, Middlesex, Morris, Somerset, Sussex, Warren111 min
Aug 21, 7:08 PM EDTSpecial Weather StatementPHIHunterdon, Middlesex, Somerset52 min
Aug 21, 7:18 PM EDTSevere Thunderstorm WarningPHIMonmouth, Ocean42 min
Aug 21, 7:21 PM EDTSpecial Marine WarningPHI84 min
Aug 21, 7:24 PM EDTFlash Flood WarningPHIMercer, Monmouth, Ocean5 hr
Aug 21, 7:35 PM EDTAreal Flood AdvisoryPHIBurlington, Mercer, Middlesex, Monmouth, Ocean115 min
Aug 21, 1:11 PM EDTSpecial Weather StatementPHIMontgomery64 min
Aug 21, 1:25 PM EDTAreal Flood AdvisoryPHIBucks, Chester, Montgomery110 min
Aug 21, 3:31 PM EDTFlash Flood WarningPHIPhiladelphia8 hr
Aug 21, 4:11 PM EDTSpecial Weather StatementPHICarbon, Monroe64 min
Aug 21, 4:19 PM EDTAreal Flood AdvisoryPHICarbon, Monroe3 hr
Aug 21, 4:53 PM EDTSpecial Weather StatementPHILehigh, Northampton67 min
Aug 21, 6:41 PM EDTSpecial Weather StatementPHIBerks64 min
Aug 21, 8:01 AM EDTSpecial Weather StatementPHICecil, Kent59 min
Aug 21, 9:08 AM EDTSpecial Weather StatementPHICecil, Kent52 min
Aug 21, 9:36 AM EDTAreal Flood AdvisoryPHICecil, Kent, Queen Anne's2 hr
Aug 21, 2:01 PM EDTSevere Thunderstorm WarningPHICecil, Kent, Queen Anne's59 min
Aug 21, 2:43 PM EDTAreal Flood AdvisoryPHICecil, Kent, Queen Anne's3 hr
Aug 21, 2:55 PM EDTSevere Thunderstorm WarningPHIKent, Queen Anne's, Talbot65 min
Aug 21, 3:11 PM EDTAreal Flood AdvisoryPHIKent, Queen Anne's2 hr
Aug 21, 4:03 PM EDTSpecial Weather StatementPHICaroline, Kent, Queen Anne's, Talbot57 min
Aug 21, 4:45 PM EDTFlash Flood WarningPHIKent3 hr
Aug 21, 5:09 PM EDTSevere Thunderstorm WarningPHICaroline, Kent, Queen Anne's, Talbot37 min
Aug 21, 5:20 PM EDTAreal Flood AdvisoryPHICaroline, Queen Anne's, Talbot115 min
Aug 21, 7:17 PM EDTAreal Flood AdvisoryPHICaroline118 min
Aug 21, 9:19 AM EDTSpecial Weather StatementPHIKent56 min
Aug 21, 10:15 AM EDTSpecial Weather StatementPHIKent60 min
Aug 21, 10:33 AM EDTSevere Thunderstorm WarningPHIKent57 min
Aug 21, 6:29 PM EDTSpecial Weather StatementPHISussex61 min
Aug 21, 7:03 PM EDTSevere Thunderstorm WarningPHIKent, Sussex42 min

Nearby

Flash Flood Watches in New Jersey, 2011Flash Flood Watches in Pennsylvania, 2011Flash Flood Watches in Maryland, 2011Every flash flood watch 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.