Alert archive / Louisiana / Flash Flood Warnings in 2021

Flash Flood Warning 110, NWS New Orleans, LA

August 31, 2021Lafourche Parish, Saint James Parish, Saint John the Baptist Parish, Louisiana

NWS New Orleans, LA issued this flash flood warning at Aug 31, 2021, 4:44 PM CDT for Lafourche Parish, Saint James Parish, Saint John the Baptist Parish, Louisiana. It was in force for 3 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 31, 2021, 4:44 PM CDT (21:44 UTC)
Expired: Aug 31, 2021, 7:32 PM CDT
In force: 3 hr
Issued by: NWS New Orleans, LA
Area: Storm-based polygon
Damage threat: Considerable
Flood severity: None

Counties Lafourche Parish, LA, Saint James Parish, LA, Saint John the Baptist Parish, LA

The nearest sounding before it

Slidell Radar S, LA (KSIL), launched 12:00Z, 9.7 hours before the alert went out and 112 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-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

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: 321 J/kg
Mixed-layer CIN: -53 J/kg
Mixed-layer LCL: 871 m above ground
0-6 km bulk shear: 24 kt
0-1 km storm-relative helicity: 186 m²/s²
0-3 km storm-relative helicity: 199 m²/s²
Significant tornado parameter: 0.1
Supercell composite: 1.7

Open this sounding in Storm Lab

The text

As transmitted.

904 
WGUS54 KLIX 312144
FFWLIX
LAC057-093-095-010045-
/O.NEW.KLIX.FF.W.0110.210831T2144Z-210901T0045Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service New Orleans LA
Issued by National Weather Service Lake Charles LA
444 PM CDT Tue Aug 31 2021

The National Weather Service in New Orleans has issued a

* Flash Flood Warning for...
  Northwestern Lafourche Parish in southeastern Louisiana...
  Southern St. James Parish in southeastern Louisiana...
  Southwestern St. John The Baptist Parish in southeastern Louisiana...

* Until 745 PM CDT.

* At 444 PM CDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Between 1 and 3 inches of rain 
  have fallen. Additional thunderstorms continue to develop and move 
  across the same area. Flash flooding is ongoing or expected to 
  begin shortly.

  HAZARD...Life threatening flash flooding. Thunderstorms
           producing flash flooding.

  SOURCE...Radar.

  IMPACT...Life threatening flash flooding of creeks and streams,
           urban areas, highways, streets and underpasses.

* Some locations that will experience flash flooding include...
  Thibodaux, South Vacherie, Chackbay, Raceland, North Vacherie and 
  Des Allemands.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3000 9095 2999 9069 2993 9054 2988 9054
      2971 9038 2973 9077 2978 9080 2979 9094
      2988 9088 2994 9088 2994 9092 2998 9092
      2998 9094

FLASH FLOOD...RADAR INDICATED
FLASH FLOOD DAMAGE THREAT...CONSIDERABLE

$$

13

2 follow-up statements

440 
WGUS74 KLIX 312338
FFSLIX

Flash Flood Statement
National Weather Service New Orleans LA
Issued by National Weather Service Lake Charles LA
638 PM CDT Tue Aug 31 2021

LAC093-095-312348-
/O.CAN.KLIX.FF.W.0110.000000T0000Z-210901T0045Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
St. James LA-St. John The Baptist LA-
638 PM CDT Tue Aug 31 2021

...FLASH FLOOD WARNING IS CANCELLED FOR SOUTHERN ST. JAMES AND 
SOUTHWESTERN ST. JOHN THE BAPTIST PARISHES...

Additional flash flooding from thunderstorms is no longer expected 
to pose a threat. Please continue to heed remaining road closures.

LAT...LON 2973 9060 2973 9077 2978 9080 2979 9094
      2988 9088 2991 9088 2991 9079 2992 9078
      2991 9073 2990 9072 2990 9069 2989 9068

$$

LAC057-010045-
/O.CON.KLIX.FF.W.0110.000000T0000Z-210901T0045Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Lafourche LA-
638 PM CDT Tue Aug 31 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 745 PM CDT THIS 
EVENING FOR NORTHWESTERN LAFOURCHE PARISH...

At 638 PM CDT, Doppler radar indicated thunderstorms producing heavy 
rain across the warned area, mainly near and to the west of 
Thibodaux. Between 1 and 2 inches of rain have fallen. Flash 
flooding is ongoing or expected to begin shortly.

HAZARD...Life threatening flash flooding. Thunderstorms producing
         flash flooding.

SOURCE...Radar.

IMPACT...Life threatening flash flooding of creeks and streams,
         urban areas, highways, streets and underpasses.

Some locations that will experience flash flooding include...
  Thibodaux, Chackbay, South Vacherie.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 2973 9060 2973 9077 2978 9080 2979 9094
      2988 9088 2991 9088 2991 9079 2992 9078
      2991 9073 2990 9072 2990 9069 2989 9068

FLASH FLOOD...RADAR INDICATED
FLASH FLOOD DAMAGE THREAT...CONSIDERABLE

$$

060 
WGUS74 KLIX 010032
FFSLIX

Flash Flood Statement
National Weather Service New Orleans LA
Issued by National Weather Service Lake Charles LA
732 PM CDT Tue Aug 31 2021

LAC057-010042-
/O.CAN.KLIX.FF.W.0110.000000T0000Z-210901T0045Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Lafourche LA-
732 PM CDT Tue Aug 31 2021

...FLASH FLOOD WARNING IS CANCELLED FOR NORTHWESTERN LAFOURCHE 
PARISH...

Flooding from thunderstorms is no longer expected to pose a threat. 
Please continue to heed remaining road closures.

LAT...LON 2973 9060 2973 9077 2978 9080 2979 9094
      2988 9088 2991 9088 2991 9079 2992 9078
      2991 9073 2990 9072 2990 9069 2989 9068

$$

13

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 31, 4:06 AM CDT	Heat Advisory	LIX	Assumption, East Baton Rouge, East Feliciana, Iberville, Orleans, Pointe Coupee and 9 more	38 hr
Aug 31, 10:02 AM CDT	Special Marine Warning	LIX		118 min
Aug 31, 1:21 PM CDT	Special Weather Statement	LIX	Saint Bernard	39 min
Aug 31, 1:58 PM CDT	Special Weather Statement	LIX	Saint Bernard	32 min
Aug 31, 2:49 PM CDT	Flash Flood Warning Considerable damage threat	LIX	Jefferson, Orleans, Plaquemines, Saint Bernard, Saint Charles	88 min
Aug 31, 3:52 PM CDT	Special Weather Statement	LIX	Saint Charles	53 min
Aug 31, 4:23 PM CDT	Special Marine Warning	LIX		2 hr
Aug 31, 4:36 PM CDT	Special Weather Statement	LIX	Lafourche	24 min
Aug 31, 5:05 PM CDT	Special Weather Statement	LIX	Lafourche	25 min
Aug 31, 5:22 PM CDT	Special Weather Statement	LIX	Assumption	53 min
Aug 31, 6:20 PM CDT	Flash Flood Warning Considerable damage threat	LIX	Saint Charles, Saint John the Baptist	49 min
Aug 31, 6:50 PM CDT	Flash Flood Warning	LIX	Assumption, Lafourche, Terrebonne	42 min

Nearby

Flash Flood Warnings in Louisiana, 2021 Every 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.