Alert archive / Louisiana / Flash Flood Warnings in 2021

Flash Flood Warning 109, NWS New Orleans, LA

August 31, 20215 parishes in Louisiana

NWS New Orleans, LA issued this flash flood warning at Aug 31, 2021, 2:49 PM CDT for 5 parishes in Louisiana. It was in force for 88 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, 2:49 PM CDT (19:49 UTC)
Expired
Aug 31, 2021, 4:17 PM CDT
In force
88 min
Issued by
NWS New Orleans, LA
Area
Storm-based polygon
Damage threat
Considerable
Flood severity
None

Counties Jefferson Parish, LA, Orleans Parish, LA, Plaquemines Parish, LA, Saint Bernard Parish, LA, Saint Charles Parish, LA

The nearest sounding before it

Slidell Radar S, LA (KSIL), launched 12:00Z, 7.8 hours before the alert went out and 48 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 2021-08-31Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 321 joules per kilogram.LCLLFCEL10008507005003002001001 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 2021-08-31The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 186 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
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.

189 
WGUS54 KLIX 311949
FFWLIX
LAC051-071-075-087-089-312300-
/O.NEW.KLIX.FF.W.0109.210831T1949Z-210831T2300Z/
/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
249 PM CDT Tue Aug 31 2021

The National Weather Service in New Orleans has issued a

* Flash Flood Warning for...
  Northwestern Jefferson Parish in southeastern Louisiana...
  Southwestern Orleans Parish in southeastern Louisiana...
  Northwestern Plaquemines Parish in southeastern Louisiana...
  West Central St. Bernard Parish in southeastern Louisiana...
  Northeastern St. Charles Parish in southeastern Louisiana...

* Until 600 PM CDT.

* At 249 PM CDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Between 1 and 3.5 inches of 
  rain have fallen. Additional rainfall amounts of 1 to 3 inches are 
  possible in the warned 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...
  New Orleans, Timberlane, Belle Chasse, Harvey, Chalmette, Marrero, 
  Avondale, Metairie, Jefferson, Gretna, Harahan, Westwego, 
  Terrytown, Arabi, Woodmere, Estelle, Meraux, Violet, Poydras and 
  Bridge City.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Be aware of your surroundings and do not drive on flooded roads.

&&

LAT...LON 2983 9025 2987 9033 2994 9038 2997 9037
      3000 9031 2997 9015 2999 8998 2997 8985
      2993 8982 2995 8975 2992 8976 2993 8975
      2990 8974 2991 8974 2986 8968 2976 8974
      2976 8985 2983 9007

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

$$

jb
2 follow-up statements
154 
WGUS74 KLIX 312044
FFSLIX

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

LAC051-071-075-087-089-312300-
/O.CON.KLIX.FF.W.0109.000000T0000Z-210831T2300Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Jefferson LA-Orleans LA-Plaquemines LA-St. Bernard LA-St. Charles LA-
344 PM CDT Tue Aug 31 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 6 PM CDT THIS EVENING 
FOR NORTHWESTERN JEFFERSON, SOUTHWESTERN ORLEANS, NORTHWESTERN 
PLAQUEMINES, WEST CENTRAL ST. BERNARD AND NORTHEASTERN ST. CHARLES 
PARISHES...

At 344 PM CDT, Doppler radar indicated thunderstorms producing heavy 
rain across the warned area. Between 1 and 4 inches of rain have 
fallen, especially between Terrytown and Yscloskey. Additional 
rainfall amounts of 1 to 3 inches are possible in the warned 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...
  New Orleans, Timberlane, Belle Chasse, Harvey, Chalmette, Marrero, 
  Avondale, Metairie, Jefferson, Gretna, Harahan, Westwego, 
  Terrytown, Arabi, Woodmere, Estelle, Meraux, Violet, Poydras and 
  Bridge City.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Be aware of your surroundings and do not drive on flooded roads.

&&

LAT...LON 2983 9025 2987 9033 2994 9038 2997 9037
      3000 9031 2997 9015 2999 8998 2997 8985
      2993 8982 2995 8975 2992 8976 2993 8975
      2990 8974 2991 8974 2986 8968 2976 8974
      2976 8985 2983 9007

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

$$
279 
WGUS74 KLIX 312117
FFSLIX

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

LAC051-071-075-087-089-312127-
/O.CAN.KLIX.FF.W.0109.000000T0000Z-210831T2300Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Jefferson LA-Orleans LA-Plaquemines LA-St. Bernard LA-St. Charles LA-
417 PM CDT Tue Aug 31 2021

...FLASH FLOOD WARNING IS CANCELLED FOR NORTHWESTERN JEFFERSON, 
SOUTHWESTERN ORLEANS, NORTHWESTERN PLAQUEMINES, WEST CENTRAL ST. 
BERNARD AND NORTHEASTERN ST. CHARLES PARISHES...

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

LAT...LON 2983 9025 2987 9033 2994 9038 2997 9037
      3000 9031 2997 9015 2999 8998 2997 8985
      2993 8982 2995 8975 2992 8976 2993 8975
      2990 8974 2991 8974 2986 8968 2976 8974
      2976 8985 2983 9007

$$

The office that day

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

IssuedProductOfficeCountiesLasted
Aug 31, 4:06 AM CDTHeat AdvisoryLIXAssumption, East Baton Rouge, East Feliciana, Iberville, Orleans, Pointe Coupee and 9 more38 hr
Aug 31, 10:02 AM CDTSpecial Marine WarningLIX118 min
Aug 31, 1:21 PM CDTSpecial Weather StatementLIXSaint Bernard39 min
Aug 31, 1:58 PM CDTSpecial Weather StatementLIXSaint Bernard32 min
Aug 31, 3:52 PM CDTSpecial Weather StatementLIXSaint Charles53 min
Aug 31, 4:23 PM CDTSpecial Marine WarningLIX2 hr
Aug 31, 4:36 PM CDTSpecial Weather StatementLIXLafourche24 min
Aug 31, 4:44 PM CDTFlash Flood Warning Considerable damage threatLIXLafourche, Saint James, Saint John the Baptist3 hr
Aug 31, 5:05 PM CDTSpecial Weather StatementLIXLafourche25 min
Aug 31, 5:22 PM CDTSpecial Weather StatementLIXAssumption53 min
Aug 31, 6:20 PM CDTFlash Flood Warning Considerable damage threatLIXSaint Charles, Saint John the Baptist49 min
Aug 31, 6:50 PM CDTFlash Flood WarningLIXAssumption, Lafourche, Terrebonne42 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.