Alert archive / Louisiana / Flash Flood Warnings in 2021

Flash Flood Warning 112, NWS New Orleans, LA

August 31, 2021Assumption Parish, Lafourche Parish, Terrebonne Parish, Louisiana

NWS New Orleans, LA issued this flash flood warning at Aug 31, 2021, 6:50 PM CDT for Assumption Parish, Lafourche Parish, Terrebonne Parish, Louisiana. It was in force for 42 min. 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, 6:50 PM CDT (23:50 UTC)
Expired: Aug 31, 2021, 7:32 PM CDT
In force: 42 min
Issued by: NWS New Orleans, LA
Area: Storm-based polygon
Flood severity: None

Counties Assumption Parish, LA, Lafourche Parish, LA, Terrebonne Parish, LA

The nearest sounding before it

Slidell Radar S, LA (KSIL), launched 12:00Z, 11.8 hours before the alert went out and 124 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.

148 
WGUS54 KLIX 312350
FFWLIX
LAC007-057-109-010045-
/O.NEW.KLIX.FF.W.0112.210831T2350Z-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
650 PM CDT Tue Aug 31 2021

The National Weather Service in New Orleans has issued a

* Flash Flood Warning for...
  Southeastern Assumption Parish in southeastern Louisiana...
  Northwestern Lafourche Parish in southeastern Louisiana...
  North Central Terrebonne Parish in southeastern Louisiana...

* Until 745 PM CDT.

* At 650 PM CDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Between 1 and 2 inches of rain 
  have fallen. 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...
  Thibodaux, Schriever, Gray and Bayou Cane.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 2979 9095 2978 9080 2973 9077 2973 9065
      2961 9065 2962 9108

FLASH FLOOD...RADAR INDICATED

$$

13

1 follow-up statement

940 
WGUS74 KLIX 010032 RRA
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

LAC007-057-109-010042-
/O.CAN.KLIX.FF.W.0112.000000T0000Z-210901T0045Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Assumption LA-Lafourche LA-Terrebonne LA-
732 PM CDT Tue Aug 31 2021

...FLASH FLOOD WARNING IS CANCELLED FOR SOUTHEASTERN ASSUMPTION, 
NORTHWESTERN LAFOURCHE AND NORTH CENTRAL TERREBONNE PARISHES...

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

LAT...LON 2979 9095 2978 9080 2973 9077 2973 9065
      2961 9065 2962 9108

$$

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, 4:44 PM CDT	Flash Flood Warning Considerable damage threat	LIX	Lafourche, Saint James, Saint John the Baptist	3 hr
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

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.