Alert archive / Louisiana / Flash Flood Warnings in 2021

Flash Flood Warning 88, NWS New Orleans, LA

August 29, 2021Plaquemines Parish, Louisiana

NWS New Orleans, LA issued this flash flood warning at Aug 29, 2021, 5:01 PM CDT for Plaquemines Parish, Louisiana. It was in force for 6 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 29, 2021, 5:01 PM CDT (22:01 UTC)
Expired
Aug 29, 2021, 11:00 PM CDT
In force
6 hr
Issued by
NWS New Orleans, LA
Area
Storm-based polygon
Emergency
Flash flood emergency
Damage threat
Catastrophic
Flood severity
None

County Plaquemines Parish, LA

The nearest sounding before it

Slidell Radar S, LA (KSIL), launched 12:00Z, 10.0 hours before the alert went out and 55 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 2021-08-29Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 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 2021-08-29The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -55 square meters per square second.193958Sfc1 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
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
3256 m above ground
0-6 km bulk shear
37 kt
0-1 km storm-relative helicity
-55 m²/s²
0-3 km storm-relative helicity
85 m²/s²
Significant tornado parameter
0.0
Supercell composite
-0.3

Open this sounding in Storm Lab

The text

As transmitted.

635 
WGUS54 KLIX 292201
FFWLIX
LAC075-300400-
/O.NEW.KLIX.FF.W.0088.210829T2201Z-210830T0400Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service New Orleans LA
501 PM CDT Sun Aug 29 2021

...FLASH FLOOD EMERGENCY FOR BRAITHWAITE AREA...

The National Weather Service in New Orleans has issued a

* Flash Flood Warning for...
  Northwestern Plaquemines Parish in southeastern Louisiana...

* Until 1100 PM CDT.

* At 501 PM CDT, emergency management reported back levee 
  over-topping on the eastbank of Plaquemines Parish between the 
  parish line and White Ditch.

  This is a FLASH FLOOD EMERGENCY for Braithwaite area. This is a 
  PARTICULARLY DANGEROUS SITUATION. SEEK HIGHER GROUND NOW!

  HAZARD...Life threatening flash flooding.

  SOURCE...Emergency management reported.

  IMPACT...This is a PARTICULARLY DANGEROUS SITUATION. SEEK
           HIGHER GROUND NOW! Life threatening flash flooding
           throughout the warned area is possible.

* Some locations that will experience flash flooding include...
  Braithwaite

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Move to higher ground now! This is an extremely dangerous and 
life-threatening situation. Do not attempt to travel unless you are 
fleeing an area subject to flooding or under an evacuation order.

Turn around, don't drown when encountering flooded roads. Most flood 
deaths occur in vehicles.

&&

LAT...LON 2986 8991 2984 8990 2982 8993 2981 8993
      2980 8995 2978 8996 2977 8998 2976 8999
      2976 9001 2977 9001 2978 9001 2980 9000
      2981 9000 2982 8999 2983 8998 2985 8997
      2986 8997 2987 8996 2988 8996

FLASH FLOOD...OBSERVED
FLASH FLOOD DAMAGE THREAT...CATASTROPHIC

$$

TD
1 follow-up statement
213 
WGUS74 KLIX 300409
FFSLIX

Flash Flood Statement
National Weather Service New Orleans LA
1109 PM CDT Sun Aug 29 2021

LAC075-300419-
/O.EXP.KLIX.FF.W.0088.000000T0000Z-210830T0400Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Plaquemines LA-
1109 PM CDT Sun Aug 29 2021

...FLASH FLOOD WARNING HAS EXPIRED FOR NORTHWESTERN PLAQUEMINES 
PARISH...

The heavy rain has ended. Flooding is no longer expected to pose a 
threat. Please continue to heed remaining road closures.

A Flash Flood Watch remains in effect until 700 AM CDT Tuesday for 
portions of southeast Louisiana and Mississippi.

LAT...LON 2986 8991 2984 8990 2982 8993 2981 8993
      2980 8995 2978 8996 2977 8998 2976 8999
      2976 9001 2977 9001 2978 9001 2980 9000
      2981 9000 2982 8999 2983 8998 2985 8997
      2986 8997 2987 8996 2988 8996

$$

CAB

The office that day

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

IssuedProductOfficeCountiesLasted
Aug 29, 6:23 AM CDTSpecial Marine WarningLIX22 min
Aug 29, 7:49 AM CDTExtreme Wind WarningLIXJefferson, Lafourche, Plaquemines, Saint Bernard, Saint Charles, Terrebonne3 hr
Aug 29, 10:30 AM CDTExtreme Wind WarningLIXJefferson, Lafourche, Plaquemines, Saint Bernard, Saint Charles, Terrebonne3 hr
Aug 29, 1:26 PM CDTExtreme Wind WarningLIXAssumption, Jefferson, Lafourche, Plaquemines, Saint Charles, Saint James and 2 more3 hr
Aug 29, 2:42 PM CDTSpecial Marine WarningLIX18 min
Aug 29, 3:39 PM CDTFlash Flood WarningLIXLafourche, Terrebonne7 hr
Aug 29, 4:08 PM CDTFlash Flood Warning EmergencyLIXJefferson, Orleans, Plaquemines, Saint Bernard, Saint Charles, Saint John the Baptist8 hr
Aug 29, 4:23 PM CDTExtreme Wind WarningLIXJefferson, Lafourche, Saint Charles, Saint James, Saint John the Baptist, Terrebonne2 hr
Aug 29, 5:04 PM CDTSpecial Marine WarningLIX26 min
Aug 29, 6:04 PM CDTSpecial Marine WarningLIX26 min
Aug 29, 6:09 PM CDTFlash Flood WarningLIXSaint Tammany8 hr
Aug 29, 6:21 PM CDTFlash Flood WarningLIXSaint Tammany16 hr
Aug 29, 6:25 PM CDTTornado WarningLIXOrleans, Saint Bernard, Saint Tammany35 min
Aug 29, 6:33 PM CDTSpecial Marine WarningLIX57 min
Aug 29, 6:54 PM CDTTornado WarningLIXSaint Tammany36 min

Nearby

Flash Flood Warnings in Louisiana, 2021Every flash flood warning in 2021

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.