Alert archive / Delaware / Areal Flood Warnings in 2011

Areal Flood Warning 45, NWS Philadelphia/Mount Holly

August 19, 2011New Castle County, Delaware; Delaware County, Pennsylvania

NWS Philadelphia/Mount Holly issued this areal flood warning at Aug 19, 2011, 4:00 AM EDT for New Castle County, Delaware; Delaware County, Pennsylvania. It was in force for 4 hr. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued
Aug 19, 2011, 4:00 AM EDT (08:00 UTC)
Expired
Aug 19, 2011, 7:54 AM EDT
In force
4 hr
Issued by
NWS Philadelphia/Mount Holly
Area
Storm-based polygon
Flood severity
None

Counties New Castle County, DE, Delaware County, PA

The radar

The Philadelphia radar (KDIX), 99 km from the middle of the area, began a volume at 08:01 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

Wallops Is Stn, VA (KWAL), launched 00:00Z, 8.0 hours before the alert went out and 211 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, Wallops Is Stn, VA at 00:00Z on 2011-08-19Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 27 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, Wallops Is Stn, VA at 00:00Z on 2011-08-19The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 5 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
27 J/kg
Mixed-layer CIN
-177 J/kg
Mixed-layer LCL
1773 m above ground
0-6 km bulk shear
15 kt
0-1 km storm-relative helicity
5 m²/s²
0-3 km storm-relative helicity
34 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.

240 
WGUS41 KPHI 190800
FLWPHI

BULLETIN - IMMEDIATE BROADCAST REQUESTED
FLOOD WARNING
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
400 AM EDT FRI AUG 19 2011

DEC003-PAC045-191345-
/O.NEW.KPHI.FA.W.0045.110819T0800Z-110819T1345Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
DELAWARE PA-NEW CASTLE DE-
400 AM EDT FRI AUG 19 2011

THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ HAS ISSUED A

* FLOOD WARNING FOR URBAN AREAS AND SMALL STREAMS IN...
  SOUTHWESTERN DELAWARE COUNTY IN SOUTHEAST PENNSYLVANIA...
  NORTHEASTERN NEW CASTLE COUNTY IN NORTHERN DELAWARE...

* UNTIL 945 AM EDT

* AT 359 AM EDT THE HEAVY OVERNIGHT RAINS HAVE ESSENTIALLY ENDED
  LEAVING CONSIDERABLE POOR DRAINAGE FLOODING IN THE URBAN AREAS OF
  FAR NORTHERN NEW CASTLE COUNTY ADJACENT THE PENNSYLVANIA DELAWARE
  BORDER.  REPORTS WERE RECEIVED OF INUNDATED ROADS AND A COUPLE OF
  HOMES ISOLATED NEAR TALLEYVILLE CLAYMONT...TO THE NORTH OF
  WILMINGTON WHERE THE HEAVIEST RAIN OCCURRED BETWEEN 1 AM AND 230
  AM.  THERE WERE ALSO REPORTS OF FLOODED BASEMENTS THERE. 

* THE BRANDYWINE CREEK HAD STOPPED ITS RAPID RISE NEAR 14.8 FEET...
  MORE THAN A FOOT AND HALF BELOW FLOOD STAGE. ABOUT 2.5 INCHES OF
  RAIN FELL IN CLAYMONT.  

THIS STATEMENT SUPERSEDES THE FLOOD ADVISORY ISSUED EARLIER FOR 
NORTHERN DELAWARE. 

A FLOOD WARNING MEANS THAT FLOODING IS IMMINENT OR HAS BEEN REPORTED.
ALL INTERESTED PARTIES SHOULD TAKE NECESSARY AVOIDANCE PRECAUTIONS 
IMMEDIATELY.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

EXCESSIVE RUNOFF FROM HEAVY RAINFALL HAS CAUSED ELEVATED LEVELS ON
SMALL CREEKS AND STREAMS...AND PONDING OF WATER IN URBAN AREAS...
HIGHWAYS...STREETS AND UNDERPASSES AS WELL AS OTHER POOR DRAINAGE
AREAS AND LOW LYING SPOTS.

A FLOOD WARNING MEANS FLOODING HAS OCCURRED. MOST FLOOD RELATED 
DEATHS OCCUR IN AUTOMOBILES. DO NOT ATTEMPT TO CROSS WATER COVERED 
BRIDGES...DIPS...OR LOW WATER CROSSINGS. NEVER TRY TO CROSS A 
FLOWING STREAM...EVEN A SMALL ONE...ON FOOT. TO ESCAPE RISING WATER 
MOVE UP TO HIGHER GROUND.

&&

LAT...LON 3984 7560 3985 7561 3989 7555 3985 7545
      3982 7540 3974 7553 3975 7557 3978 7560
      3983 7561 3984 7561

$$

DRAG
2 follow-up statements
900 
WGUS81 KPHI 190837
FLSPHI

FLOOD STATEMENT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
437 AM EDT FRI AUG 19 2011

DEC003-PAC045-191345-
/O.CON.KPHI.FA.W.0045.000000T0000Z-110819T1345Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
DELAWARE PA-NEW CASTLE DE-
437 AM EDT FRI AUG 19 2011

...THE FLOOD WARNING REMAINS IN EFFECT UNTIL 945 AM EDT FOR URBAN
AREAS AND SMALL STREAMS IN NORTHEASTERN NEW CASTLE AND SOUTHWESTERN
DELAWARE COUNTIES...

AT 429 AM EDT THE HEAVY OVERNIGHT RAINS /ABOUT 2.5 INCHES IN 
CLAYMONT/ HAVE ENDED LEAVING CONSIDERABLE POOR DRAINAGE FLOODING IN 
THE URBAN AREAS OF FAR NORTHERN NEW CASTLE COUNTY ADJACENT THE 
PENNSYLVANIA DELAWARE BORDER. REPORTS WERE RECEIVED OF INUNDATED 
ROADS AND A COUPLE OF HOMES ISOLATED NEAR TALLEYVILLE CLAYMONT... 
NORTH OF WILMINGTON WHERE THE HEAVIEST RAIN OCCURRED BETWEEN 1 AM 
AND 230 AM. THERE WERE ALSO REPORTS OF FLOODED BASEMENTS THERE. 

* THE BRANDYWINE CREEK IN NORTHERN NEWCASTLE COUNTY HAD STOPPED ITS
  RAPID RISE NEAR 14.8 FEET...MORE THAN A FOOT AND HALF BELOW FLOOD
  STAGE. 

* HOWEVER ON THE PENNSYLVANIA SIDE...THERE WAS A REPORT FROM CHESTER
  COUNTY THAT THE BRANDYWINE WAS OUT OF ITS BANKS AND CLOSED A ROAD
  IN BIRMINGHAM TOWNSHIP...JUST SOUTH OF WEST CHESTER. 

THIS STATEMENT SUPERSEDES THE FLOOD ADVISORY ISSUED EARLIER FOR 
NORTHERN DELAWARE. 

A FLOOD WARNING MEANS THAT FLOODING IS IMMINENT OR HAS BEEN REPORTED.
ALL INTERESTED PARTIES SHOULD TAKE NECESSARY FLOOD WATER AVOIDANCE 
PRECAUTIONS IMMEDIATELY.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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.

EXCESSIVE RUNOFF FROM HEAVY RAINFALL WILL CAUSE ELEVATED LEVELS ON
SMALL CREEKS AND STREAMS...AND PONDING OF WATER ON COUNTRY ROADS AND
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.

&&

LAT...LON 3984 7560 3985 7561 3989 7555 3985 7545
      3982 7540 3974 7553 3975 7557 3978 7560
      3983 7561 3984 7561

$$

DRAG
852 
WGUS81 KPHI 191154
FLSPHI

FLOOD STATEMENT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
754 AM EDT FRI AUG 19 2011

DEC003-PAC045-191202-
/O.CAN.KPHI.FA.W.0045.000000T0000Z-110819T1345Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
DELAWARE PA-NEW CASTLE DE-
754 AM EDT FRI AUG 19 2011

...THE FLOOD WARNING HAS BEEN CANCELLED FOR URBAN AREAS AND SMALL
STREAMS IN NORTHEASTERN NEW CASTLE AND SOUTHWESTERN DELAWARE
COUNTIES...

THE WATER LEVELS ON THE GAGED STREAMS IN THE AREA ARE GENERALLY 
FALLING. ANY LINGERING POCKETS OF POOR DRAINAGE FLOODING WILL ALSO 
END SHORTLY. THEREFORE, THE FLOOD WARNING HAS BEEN CANCELLED. 


LAT...LON 3984 7560 3985 7561 3989 7555 3985 7545
      3982 7540 3974 7553 3975 7557 3978 7560
      3983 7561 3984 7561

$$

GORSE

The office that day

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

IssuedProductOfficeCountiesLasted
Aug 18, 8:26 PM EDTAreal Flood AdvisoryPHINew Castle112 min
Aug 19, 12:50 AM EDTSpecial Weather StatementPHINew Castle40 min
Aug 19, 1:14 AM EDTAreal Flood AdvisoryPHINew Castle3 hr
Aug 19, 1:44 AM EDTSpecial Weather StatementPHINew Castle61 min
Aug 19, 3:06 AM EDTAreal Flood AdvisoryPHIKent114 min
Aug 19, 1:20 PM EDTSpecial Weather StatementPHIKent, Sussex85 min
Aug 19, 1:42 PM EDTSevere Thunderstorm WarningPHISussex63 min
Aug 19, 2:09 PM EDTAreal Flood AdvisoryPHISussex92 min
Aug 19, 2:33 PM EDTAreal Flood AdvisoryPHIKent, New Castle7 hr
Aug 19, 2:53 PM EDTSevere Thunderstorm WarningPHIKent, New Castle52 min
Aug 19, 2:59 PM EDTSevere Thunderstorm WarningPHISussex61 min
Aug 19, 3:13 PM EDTSpecial Weather StatementPHISussex92 min
Aug 19, 3:53 PM EDTAreal Flood AdvisoryPHIKent, Sussex5 hr
Aug 19, 4:09 PM EDTSevere Thunderstorm WarningPHIKent66 min
Aug 19, 4:23 PM EDTSevere Thunderstorm WarningPHISussex82 min
Aug 19, 4:42 PM EDTAreal Flood AdvisoryPHINew Castle4 hr
Aug 19, 4:42 PM EDTSevere Thunderstorm WarningPHIKent, Sussex63 min
Aug 19, 6:14 PM EDTSevere Thunderstorm WarningPHINew Castle65 min
Aug 19, 6:34 PM EDTAreal Flood AdvisoryPHISussex2 hr
Aug 18, 8:08 PM EDTSpecial Weather StatementPHIBerks67 min
Aug 18, 8:31 PM EDTSevere Thunderstorm WarningPHIBucks, Montgomery59 min
Aug 18, 8:48 PM EDTSpecial Weather StatementPHIMonroe57 min
Aug 18, 8:48 PM EDTSevere Thunderstorm WarningPHIBucks57 min
Aug 19, 12:02 AM EDTSpecial Weather StatementPHIChester58 min
Aug 19, 1:31 AM EDTSpecial Weather StatementPHIDelaware, Philadelphia59 min
Aug 19, 1:46 PM EDTSevere Thunderstorm WarningPHIMonroe59 min
Aug 19, 2:35 PM EDTSevere Thunderstorm WarningPHICarbon, Monroe70 min
Aug 19, 2:38 PM EDTAreal Flood AdvisoryPHICarbon, Monroe3 hr
Aug 19, 2:57 PM EDTFlash Flood WarningPHICarbon, Monroe3 hr
Aug 19, 3:47 PM EDTSevere Thunderstorm WarningPHICarbon, Monroe58 min
Aug 19, 4:29 PM EDTSevere Thunderstorm WarningPHICarbon, Lehigh, Monroe, Northampton61 min
Aug 19, 4:32 PM EDTAreal Flood AdvisoryPHIBerks, Lehigh, Northampton2 hr
Aug 19, 4:52 PM EDTSevere Thunderstorm WarningPHIBerks, Bucks, Lehigh, Montgomery, Northampton53 min
Aug 19, 5:35 PM EDTSevere Thunderstorm WarningPHIChester55 min
Aug 19, 5:39 PM EDTAreal Flood AdvisoryPHIChester, Delaware3 hr
Aug 19, 5:42 PM EDTSevere Thunderstorm WarningPHIChester, Montgomery48 min
Aug 19, 5:45 PM EDTAreal Flood AdvisoryPHIBucks, Montgomery, Philadelphia3 hr
Aug 19, 5:59 PM EDTSevere Thunderstorm WarningPHIBucks80 min

Nearby

Areal Flood Warnings in Delaware, 2011Areal Flood Warnings in Pennsylvania, 2011Every areal 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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.