Alert archive / Louisiana / Flash Flood Warnings in 2011

Flash Flood Warning 21, NWS New Orleans, LA

July 27, 2011Jefferson Parish, Louisiana

NWS New Orleans, LA issued this flash flood warning at Jul 27, 2011, 2:54 PM CDT for Jefferson Parish, Louisiana. It was in force for 3 hr. 2 reports 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
Jul 27, 2011, 2:54 PM CDT (19:54 UTC)
Expired
Jul 27, 2011, 6:00 PM CDT
In force
3 hr
Issued by
NWS New Orleans, LA
Area
Storm-based polygon
Flood severity
None

County Jefferson Parish, LA

What was reported inside it

TimeReportWhereRemark
Jul 27, 3:45 PM CDTFLASH FLOOD1 Sw Metairie, LAPUBLIC REPORTED NUMEROUS STREETS FLOODED INCLUDING PARTS OF AIRLINE HIGHWAY...JEFFERSON HIGHWAY AND SOME SMALLER RESIDENTAL STREETS. JEFFERSON HIGHWAY WAS NEARLY IMPASSABLE AT CLEARVIEW.
Jul 27, 4:45 PM CDTFLASH FLOOD1 Sw Metairie, LAPUBLIC REPORTED NUMEROUS STREETS FLOODED INCLUDING PARTS OF AIRLINE HIGHWAY...JEFFERSON HIGHWAY AND SOME SMALLER RESIDENTAL STREETS. JEFFERSON HIGHWAY WAS NEARLY IMPASSABLE AT CLEARVIEW.

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

The nearest sounding before it

Slidell Radar S, LA (KSIL), launched 12:00Z, 7.9 hours before the alert went out and 59 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, Slidell Radar S, LA at 12:00Z on 2011-07-27Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1697 joules per kilogram.LCLEL10008507005003002001001 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, Slidell Radar S, LA at 12:00Z on 2011-07-27The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -15 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
1697 J/kg
Mixed-layer CIN
-2 J/kg
Mixed-layer LCL
453 m above ground
0-6 km bulk shear
1 kt
0-1 km storm-relative helicity
-15 m²/s²
0-3 km storm-relative helicity
2 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.

379 
WGUS54 KLIX 271954
FFWLIX
LAC051-272300-
/O.NEW.KLIX.FF.W.0021.110727T1954Z-110727T2300Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE NEW ORLEANS LA
254 PM CDT WED JUL 27 2011

THE NATIONAL WEATHER SERVICE IN NEW ORLEANS HAS ISSUED A

* FLASH FLOOD WARNING FOR...
  NORTHWESTERN JEFFERSON PARISH IN SOUTHEAST LOUISIANA...
  THIS INCLUDES THE CITIES OF...METAIRIE...KENNER...

* UNTIL 600 PM CDT

* AT 252 PM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED
  FLASH FLOODING FROM A THUNDERSTORM OVER THE WARNED AREA.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

ADDITIONAL RAINFALL AMOUNTS OF ONE TO TWO INCHES IS POSSIBLE IN THE 
WARNED AREA.

EXCESSIVE RUNOFF FROM HEAVY RAINFALL WILL CAUSE FLOODING OF URBAN 
AREAS...HIGHWAYS...STREETS AND UNDERPASSES AS WELL AS OTHER DRAINAGE 
AREAS AND LOW LYING SPOTS.

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.

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 2991 9027 3006 9028 3003 9012 2992 9014

$$

98/SO

The office that day

Everything else NWS New Orleans, LA issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Jul 27, 6:35 AM CDTSpecial Marine WarningLIX40 min
Jul 27, 12:52 PM CDTTornado WarningLIXOrleans, Saint Bernard23 min
Jul 27, 1:45 PM CDTAreal Flood AdvisoryLIXSaint Charles2 hr
Jul 27, 1:56 PM CDTAreal Flood AdvisoryLIXAscension, Livingston2 hr
Jul 27, 3:29 PM CDTAreal Flood AdvisoryLIXEast Baton Rouge2 hr

Nearby

Flash Flood Warnings in Louisiana, 2011Every 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.