Alert archive / Louisiana / Flash Flood Warnings in 2021

Flash Flood Warning 86, NWS New Orleans, LA

August 29, 2021Lafourche Parish, Terrebonne Parish, Louisiana

NWS New Orleans, LA issued this flash flood warning at Aug 29, 2021, 3:39 PM CDT for Lafourche Parish, Terrebonne Parish, Louisiana. It was in force for 7 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, 3:39 PM CDT (20:39 UTC)
Expired
Aug 29, 2021, 10:18 PM CDT
In force
7 hr
Issued by
NWS New Orleans, LA
Area
Storm-based polygon
Flood severity
None

Counties Lafourche Parish, LA, Terrebonne Parish, LA

The nearest sounding before it

Slidell Radar S, LA (KSIL), launched 12:00Z, 8.7 hours before the alert went out and 111 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.

274 
WGUS54 KLIX 292039
FFWLIX
LAC057-109-300230-
/O.NEW.KLIX.FF.W.0086.210829T2039Z-210830T0230Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

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

The National Weather Service in New Orleans has issued a

* Flash Flood Warning for...
  Central Lafourche Parish in southeastern Louisiana...
  Northeastern Terrebonne Parish in southeastern Louisiana...

* Until 930 PM CDT.

* At 339 PM CDT, Doppler radar indicated tropical rainbands and 
  thunderstorms producing persistent heavy rain across the warned 
  area. Flash flooding is ongoing or expected to begin shortly.

  HAZARD...Flash flooding caused by persistent heavy rainfall and
           slow drainage due to high tides and storm surge.

  SOURCE...Radar.

  IMPACT...Flash flooding of small creeks and streams, urban
           areas, highways, streets and underpasses as well as
           other poor drainage and low-lying areas.

* Some locations that will experience flash flooding include...
  Houma, Larose, Cut Off, Galliano, Lockport, Golden Meadow, 
  Montegut, Mathews, Chauvin, Raceland, Bayou Cane and Gray.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 2972 9063 2973 9058 2971 9052 2963 9043
      2962 9040 2957 9035 2937 9026 2935 9030
      2947 9041 2951 9049 2947 9056 2951 9065
      2953 9079 2956 9081 2961 9081 2966 9076

FLASH FLOOD...RADAR INDICATED

$$

TD
2 follow-up statements
897 
WGUS54 KLIX 300222
FFWLIX
LAC057-109-300330-
/O.EXT.KLIX.FF.W.0086.000000T0000Z-210830T0330Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

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

The National Weather Service in New Orleans has extended the

* Flash Flood Warning for...
  Central Lafourche Parish in southeastern Louisiana...
  Northeastern Terrebonne Parish in southeastern Louisiana...

* Until 1030 PM CDT.

* At 922 PM CDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Flash flooding is ongoing or 
  expected to begin shortly.

  HAZARD...Flash flooding caused by thunderstorms.

  SOURCE...Radar.

  IMPACT...Flash flooding of small creeks and streams, urban
           areas, highways, streets and underpasses as well as
           other poor drainage and low-lying areas.

* Some locations that will experience flash flooding include...
  Houma, Larose, Cut Off, Galliano, Lockport, Golden Meadow, 
  Montegut, Mathews, Chauvin, Raceland, Bayou Cane and Gray.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 2972 9063 2973 9058 2971 9052 2963 9043
      2962 9040 2957 9035 2937 9026 2935 9030
      2947 9041 2951 9049 2947 9056 2951 9065
      2953 9079 2956 9081 2961 9081 2966 9076

FLASH FLOOD...RADAR INDICATED

$$

BL
963 
WGUS74 KLIX 300318
FFSLIX

Flash Flood Statement
National Weather Service New Orleans LA
1018 PM CDT Sun Aug 29 2021

LAC057-109-300328-
/O.CAN.KLIX.FF.W.0086.000000T0000Z-210830T0330Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Lafourche LA-Terrebonne LA-
1018 PM CDT Sun Aug 29 2021

...FLASH FLOOD WARNING IS CANCELLED FOR CENTRAL LAFOURCHE AND 
NORTHEASTERN TERREBONNE PARISHES...

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 2972 9063 2973 9058 2971 9052 2963 9043
      2962 9040 2957 9035 2937 9026 2935 9030
      2947 9041 2951 9049 2947 9056 2951 9065
      2953 9079 2956 9081 2961 9081 2966 9076

$$

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, 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, 5:01 PM CDTFlash Flood Warning EmergencyCatastrophic damage threatLIXPlaquemines6 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.