Alert archive / Louisiana / Flash Flood Warnings in 2021

Flash Flood Warning 45, NWS New Orleans, LA

May 20, 20217 parishes in Louisiana

NWS New Orleans, LA issued this flash flood warning at May 20, 2021, 10:04 AM CDT for 7 parishes in Louisiana. It was in force for 13 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: May 20, 2021, 10:04 AM CDT (15:04 UTC)
Expired: May 20, 2021, 10:45 PM CDT
In force: 13 hr
Issued by: NWS New Orleans, LA
Area: Storm-based polygon
Flood severity: None

Counties Ascension Parish, LA, Assumption Parish, LA, Iberville Parish, LA, Lafourche Parish, LA, Livingston Parish, LA, Saint James Parish, LA, Terrebonne Parish, LA

The nearest sounding before it

Slidell Radar S, LA (KSIL), launched 12:00Z, 3.1 hours before the alert went out and 108 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: 622 J/kg
Mixed-layer CIN: -1 J/kg
Mixed-layer LCL: 599 m above ground
0-6 km bulk shear: 19 kt
0-1 km storm-relative helicity: 152 m²/s²
0-3 km storm-relative helicity: 227 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

115 
WGUS54 KLIX 201504
FFWLIX
LAC005-007-047-057-063-093-109-201800-
/O.NEW.KLIX.FF.W.0045.210520T1504Z-210520T1800Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service New Orleans LA
1004 AM CDT Thu May 20 2021

The National Weather Service in New Orleans has issued a

* Flash Flood Warning for...
  Southern Ascension Parish in southeastern Louisiana...
  Assumption Parish in southeastern Louisiana...
  Southeastern Iberville Parish in southeastern Louisiana...
  Northwestern Lafourche Parish in southeastern Louisiana...
  Southern Livingston Parish in southeastern Louisiana...
  St. James Parish in southeastern Louisiana...
  North Central Terrebonne Parish in southeastern Louisiana...

* Until 100 PM CDT.

* At 1004 AM CDT, the public reported 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. 
  Many levees are close to the top and any additional rain could 
  quickly lead to over topping into the marshes per emergency 
  management.

  HAZARD...Flash flooding caused by thunderstorms.

  SOURCE...Emergency management

  IMPACT...Flooding of small creeks and streams, urban areas,
           highways, streets and underpasses as well as other
           drainage and low lying areas.

* Some locations that will experience flash flooding include...
  Thibodaux, Gonzales, Donaldsonville, Napoleonville, St. Gabriel, 
  Gramercy, Lutcher, White Castle, Sorrento, Convent, Chackbay, 
  Labadieville, Supreme, South Vacherie, North Vacherie, Schriever, 
  Paincourtville, Belle Rose, Wallace and Gray.

This includes the following Interstates...
	Interstate 10 in Louisiana between mile markers 180 and 196.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3022 9118 3022 9106 3018 9081 3021 9063
      3010 9065 3009 9067 3005 9066 3003 9069
      2998 9067 2995 9067 2989 9066 2989 9060
      2989 9059 2966 9056 2965 9108 3005 9111

FLASH FLOOD...OBSERVED

$$

CAB

7 follow-up statements

218 
WGUS54 KLIX 201734
FFWLIX
LAC005-007-047-057-063-093-109-202000-
/O.EXT.KLIX.FF.W.0045.000000T0000Z-210520T2000Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service New Orleans LA
1234 PM CDT Thu May 20 2021

The National Weather Service in New Orleans has extended the

* Flash Flood Warning for...
  Southern Ascension Parish in southeastern Louisiana...
  Assumption Parish in southeastern Louisiana...
  Southeastern Iberville Parish in southeastern Louisiana...
  Northwestern Lafourche Parish in southeastern Louisiana...
  Southwestern Livingston Parish in southeastern Louisiana...
  St. James Parish in southeastern Louisiana...
  Northern Terrebonne Parish in southeastern Louisiana...

* Until 300 PM CDT.

* At 1234 PM CDT, the public reported thunderstorms producing heavy 
  rain across the warned area. Between 1.5 and 3 inches of rain have 
  fallen. Flash flooding is ongoing or expected to begin shortly.

  HAZARD...Flash flooding caused by thunderstorms.

  SOURCE...Public.

  IMPACT...Flooding of small creeks and streams, urban areas,
           highways, streets and underpasses as well as other
           drainage and low lying areas.

* Some locations that will experience flash flooding include...
  Thibodaux, Gonzales, Donaldsonville, Napoleonville, St. Gabriel, 
  Gramercy, Lutcher, White Castle, Sorrento, Convent, Chackbay, 
  Supreme, Paincourtville, Labadieville, Belle Rose, North Vacherie, 
  South Vacherie, Wallace, Schriever and Geismar.

This includes the following Interstates...
	Interstate 10 in Louisiana between mile markers 179 and 196.

Additional rainfall amounts of 0.5 to 1.5 inches are possible in the 
warned area.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3022 9118 3022 9106 3018 9081 3021 9063
      3010 9065 3009 9067 3005 9066 3003 9069
      2998 9067 2995 9067 2975 9064 2975 9109
      3005 9111

FLASH FLOOD...OBSERVED

$$

CAB

198 
WGUS54 KLIX 201934
FFWLIX
LAC005-007-047-063-093-202200-
/O.EXT.KLIX.FF.W.0045.000000T0000Z-210520T2200Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service New Orleans LA
234 PM CDT Thu May 20 2021

The National Weather Service in New Orleans has extended the

* Flash Flood Warning for...
  Southern Ascension Parish in southeastern Louisiana...
  Northeastern Assumption Parish in southeastern Louisiana...
  Southeastern Iberville Parish in southeastern Louisiana...
  Southwestern Livingston Parish in southeastern Louisiana...
  St. James Parish in southeastern Louisiana...

* Until 500 PM CDT.

* At 234 PM CDT, the public reported thunderstorms producing heavy 
  rain across the warned area. Between 1.5 and 3 inches of rain have 
  fallen. Flash flooding is ongoing or expected to begin shortly.

  HAZARD...Flash flooding caused by thunderstorms.

  SOURCE...Public.

  IMPACT...Flooding of small creeks and streams, urban areas,
           highways, streets and underpasses as well as other
           drainage and low lying areas.

* Some locations that will experience flash flooding include...
  Gonzales, Donaldsonville, Napoleonville, St. Gabriel, Gramercy, 
  Lutcher, White Castle, Sorrento, Convent, Belle Rose, 
  Paincourtville, Geismar, North Vacherie, Chackbay, South Vacherie, 
  Wallace and Garyville.

This includes the following Interstates...
	Interstate 10 in Louisiana between mile markers 179 and 196.

Additional rainfall amounts of 0.5 to 1.5 inches are possible in the 
warned area.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3022 9118 3022 9106 3018 9081 3021 9063
      3010 9065 3009 9067 3005 9066 3004 9069
      3003 9069 2999 9067 2998 9068 2998 9067
      2991 9068 2991 9073 2992 9079 2991 9079
      2990 9109 3005 9111

FLASH FLOOD...OBSERVED

$$

CAB

391 
WGUS74 KLIX 201934
FFSLIX

Flash Flood Statement
National Weather Service New Orleans LA
234 PM CDT Thu May 20 2021

LAC057-109-201944-
/O.CAN.KLIX.FF.W.0045.000000T0000Z-210520T2000Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Lafourche LA-Terrebonne LA-
234 PM CDT Thu May 20 2021

...FLASH FLOOD WARNING IS CANCELLED FOR NORTHWESTERN LAFOURCHE AND 
NORTHERN TERREBONNE PARISHES...

Flooding is no longer expected to pose a threat at this time. Please 
continue to heed remaining road closures.

A Flash Flood Watch remains in effect until 700 PM CDT for a portion 
of southeast Louisiana and more rain is anticipated to move in later 
today.

LAT...LON 3022 9118 3022 9106 3018 9081 3021 9063
      3010 9065 3009 9067 3005 9066 3004 9069
      3003 9069 2999 9067 2998 9068 2998 9067
      2991 9068 2991 9073 2992 9079 2991 9079
      2990 9109 3005 9111

$$

LAC005-007-047-063-093-202000-
/O.CON.KLIX.FF.W.0045.000000T0000Z-210520T2000Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Ascension LA-Assumption LA-Iberville LA-Livingston LA-St. James LA-
234 PM CDT Thu May 20 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 3 PM CDT THIS 
AFTERNOON FOR SOUTHERN ASCENSION, NORTHEASTERN ASSUMPTION, 
SOUTHEASTERN IBERVILLE, SOUTHWESTERN LIVINGSTON AND ST. JAMES 
PARISHES...

At 234 PM CDT, the public reported thunderstorms producing heavy 
rain across the warned area. Between 1.5 and 3 inches of rain have 
fallen. Flash flooding is ongoing or expected to begin shortly.

HAZARD...Flash flooding caused by thunderstorms.

SOURCE...Public.

IMPACT...Flooding of small creeks and streams, urban areas,
         highways, streets and underpasses as well as other
         drainage and low lying areas.

Some locations that will experience flash flooding include...
  Gonzales, Donaldsonville, Napoleonville, St. Gabriel, Gramercy, 
  Lutcher, White Castle, Sorrento, Convent, Belle Rose, 
  Paincourtville, Geismar, North Vacherie, Chackbay, South Vacherie, 
  Wallace and Garyville.

This includes the following Interstates...
	Interstate 10 in Louisiana between mile markers 179 and 196.

Additional rainfall amounts of 0.5 to 1.5 inches are possible in the 
warned area.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3022 9118 3022 9106 3018 9081 3021 9063
      3010 9065 3009 9067 3005 9066 3004 9069
      3003 9069 2999 9067 2998 9068 2998 9067
      2991 9068 2991 9073 2992 9079 2991 9079
      2990 9109 3005 9111

FLASH FLOOD...OBSERVED

$$

CAB

230 
WGUS54 KLIX 202139
FFWLIX
LAC005-007-047-063-093-210000-
/O.EXT.KLIX.FF.W.0045.000000T0000Z-210521T0000Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service New Orleans LA
439 PM CDT Thu May 20 2021

The National Weather Service in New Orleans has extended the

* Flash Flood Warning for...
  Southern Ascension Parish in southeastern Louisiana...
  Northeastern Assumption Parish in southeastern Louisiana...
  Southeastern Iberville Parish in southeastern Louisiana...
  Southwestern Livingston Parish in southeastern Louisiana...
  St. James Parish in southeastern Louisiana...

* Until 700 PM CDT.

* At 439 PM CDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Between 5 and 15 inches of rain 
  have fallen over the last 2 days. Flash flooding is expected to 
  begin as another band of moderate to heavy rain moves in over the 
  next few hours.

  HAZARD...Flash flooding caused by thunderstorms.

  SOURCE...Doppler radar.

  IMPACT...Flooding of small creeks and streams, urban areas,
           highways, streets and underpasses as well as other
           drainage and low lying areas.

* Some locations that will experience flash flooding include...
  Gonzales, Donaldsonville, Napoleonville, St. Gabriel, Gramercy, 
  Lutcher, White Castle, Sorrento, Convent, Belle Rose, 
  Paincourtville, Geismar, North Vacherie, Chackbay, South Vacherie, 
  Wallace and Garyville.

This includes the following Interstates...
	Interstate 10 in Louisiana between mile markers 179 and 196.

Additional rainfall amounts of 1.5 to 4 inches are possible in the 
warned area.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3022 9118 3022 9106 3018 9081 3021 9063
      3010 9065 3009 9067 3005 9066 3004 9069
      3003 9069 2999 9067 2998 9068 2998 9067
      2991 9068 2991 9073 2992 9079 2991 9079
      2990 9109 3005 9111

FLASH FLOOD...RADAR INDICATED
EXPECTED RAINFALL...1.5-4 INCHES IN 8 HOURS 

$$

CAB

351 
WGUS54 KLIX 202343
FFWLIX
LAC005-007-047-063-093-210200-
/O.EXT.KLIX.FF.W.0045.000000T0000Z-210521T0200Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service New Orleans LA
643 PM CDT Thu May 20 2021

The National Weather Service in New Orleans has extended the

* Flash Flood Warning for...
  Southern Ascension Parish in southeastern Louisiana...
  Northeastern Assumption Parish in southeastern Louisiana...
  Southeastern Iberville Parish in southeastern Louisiana...
  Southwestern Livingston Parish in southeastern Louisiana...
  St. James Parish in southeastern Louisiana...

* Until 900 PM CDT.

* At 643 PM CDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Between 5 and 15 inches of rain 
  have fallen. Flash flooding is ongoing or expected to begin 
  shortly.

  HAZARD...Flash flooding caused by thunderstorms.

  SOURCE...Doppler radar.

  IMPACT...Flooding of small creeks and streams, urban areas,
           highways, streets and underpasses as well as other
           drainage and low lying areas.

* Some locations that will experience flash flooding include...
  Gonzales, Donaldsonville, Napoleonville, St. Gabriel, Gramercy, 
  Lutcher, White Castle, Sorrento, Convent, Belle Rose, 
  Paincourtville, Geismar, North Vacherie, Chackbay, South Vacherie, 
  Wallace and Garyville.

This includes the following Interstates...
	Interstate 10 in Louisiana between mile markers 179 and 196.

Additional rainfall amounts of 1.5 to 4 inches are possible in the 
warned area.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3022 9118 3022 9106 3018 9081 3021 9063
      3010 9065 3009 9067 3005 9066 3004 9069
      3003 9069 2999 9067 2998 9068 2998 9067
      2991 9068 2991 9073 2992 9079 2991 9079
      2990 9109 3005 9111

FLASH FLOOD...RADAR INDICATED
EXPECTED RAINFALL...1.5-4 INCHES IN 8 HOURS 

$$

158 
WGUS54 KLIX 210140
FFWLIX
LAC005-007-047-063-093-210400-
/O.EXT.KLIX.FF.W.0045.000000T0000Z-210521T0400Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service New Orleans LA
840 PM CDT Thu May 20 2021

The National Weather Service in New Orleans has extended the

* Flash Flood Warning for...
  Southern Ascension Parish in southeastern Louisiana...
  Northeastern Assumption Parish in southeastern Louisiana...
  Southeastern Iberville Parish in southeastern Louisiana...
  Southwestern Livingston Parish in southeastern Louisiana...
  St. James Parish in southeastern Louisiana...

* Until 1100 PM CDT.

* At 840 PM CDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Between 5 and 15 inches of rain 
  have fallen over the last few days. Flash flooding is ongoing or 
  expected to begin shortly.

  HAZARD...Flash flooding caused by thunderstorms.

  SOURCE...Doppler radar.

  IMPACT...Flooding of small creeks and streams, urban areas,
           highways, streets and underpasses as well as other
           drainage and low lying areas.

* Some locations that will experience flash flooding include...
  Gonzales, Donaldsonville, Napoleonville, St. Gabriel, Gramercy, 
  Lutcher, White Castle, Sorrento, Convent, Belle Rose, 
  Paincourtville, Geismar, North Vacherie, Chackbay, South Vacherie, 
  Wallace and Garyville.

This includes the following Interstates...
	Interstate 10 in Louisiana between mile markers 179 and 196.

Additional rainfall amounts of 1 to 2 inches are possible in the 
warned area.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3022 9118 3022 9106 3018 9081 3021 9063
      3010 9065 3009 9067 3005 9066 3004 9069
      3003 9069 2999 9067 2998 9068 2998 9067
      2991 9068 2991 9073 2992 9079 2991 9079
      2990 9109 3005 9111

FLASH FLOOD...RADAR INDICATED
EXPECTED RAINFALL...1-2 INCHES IN 2 HOURS 

$$

612 
WGUS74 KLIX 210345
FFSLIX

Flash Flood Statement
National Weather Service New Orleans LA
1045 PM CDT Thu May 20 2021

LAC005-007-047-063-093-210355-
/O.CAN.KLIX.FF.W.0045.000000T0000Z-210521T0400Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Ascension LA-Assumption LA-Iberville LA-Livingston LA-St. James LA-
1045 PM CDT Thu May 20 2021

...FLASH FLOOD WARNING IS CANCELLED FOR SOUTHERN ASCENSION, 
NORTHEASTERN ASSUMPTION, SOUTHEASTERN IBERVILLE, SOUTHWESTERN 
LIVINGSTON AND ST. JAMES PARISHES...

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

A Flash Flood Watch remains in effect until 1200 PM CDT Friday for a 
portion of southeast Louisiana.

LAT...LON 3022 9118 3022 9106 3018 9081 3021 9063
      3010 9065 3009 9067 3005 9066 3004 9069
      3003 9069 2999 9067 2998 9068 2998 9067
      2991 9068 2991 9073 2992 9079 2991 9079
      2990 9109 3005 9111

$$

The office that day

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

Issued	Product	Office	Counties	Lasted
May 19, 7:03 PM CDT	Special Weather Statement	LIX	Saint Tammany	42 min
May 19, 7:24 PM CDT	Special Marine Warning	LIX		81 min
May 19, 8:00 PM CDT	Severe Thunderstorm Warning	LIX	Saint Charles, Saint John the Baptist	25 min
May 19, 8:30 PM CDT	Special Marine Warning	LIX		30 min
May 19, 9:19 PM CDT	Areal Flood Advisory	LIX	Ascension, East Baton Rouge, Iberville, Livingston	116 min
May 20, 3:42 AM CDT	Special Weather Statement	LIX	Ascension, Assumption, Iberville, Jefferson, Plaquemines, Saint Charles and 3 more	63 min
May 20, 4:05 AM CDT	Special Marine Warning	LIX		55 min
May 20, 4:18 AM CDT	Special Marine Warning	LIX		57 min
May 20, 5:03 AM CDT	Special Marine Warning	LIX		57 min
May 20, 5:33 AM CDT	Special Marine Warning	LIX		57 min
May 20, 7:00 AM CDT	Special Weather Statement	LIX	Assumption, Jefferson, Lafourche, Saint Charles, Saint James	60 min
May 20, 7:39 AM CDT	Tornado Warning	LIX	Jefferson	8 min
May 20, 7:42 AM CDT	Special Marine Warning	LIX		33 min
May 20, 8:27 AM CDT	Special Marine Warning	LIX		63 min
May 20, 8:37 AM CDT	Areal Flood Advisory	LIX	Ascension, Assumption, East Baton Rouge, Iberville, Lafourche, Livingston and 3 more	52 min
May 20, 8:58 AM CDT	Tornado Warning	LIX	East Feliciana	13 min
May 20, 9:29 AM CDT	Flash Flood Warning	LIX	Ascension, East Baton Rouge, Iberville, Livingston, West Baton Rouge	9 hr
May 20, 9:45 AM CDT	Flash Flood Warning	LIX	East Baton Rouge, East Feliciana, Saint Helena, West Feliciana	11 hr
May 20, 10:52 AM CDT	Severe Thunderstorm Warning	LIX	Saint Charles, Saint John the Baptist	19 min
May 20, 11:22 AM CDT	Special Marine Warning	LIX		38 min
May 20, 11:26 AM CDT	Severe Thunderstorm Warning	LIX	East Baton Rouge, East Feliciana, Livingston, Saint Helena	94 min
May 20, 2:16 PM CDT	River Flood Warning	LIX	East Baton Rouge, Livingston	68 hr
May 20, 2:22 PM CDT	River Flood Warning	LIX	Ascension, Livingston	4 days
May 20, 2:33 PM CDT	Special Marine Warning	LIX		57 min
May 20, 2:40 PM CDT	River Flood Warning	LIX	East Baton Rouge	61 hr
May 20, 3:29 PM CDT	Special Marine Warning	LIX		61 min
May 20, 3:56 PM CDT	Gale Warning	LIX		19 hr
May 20, 3:56 PM CDT	Small Craft Advisory	LIX		60 hr
May 20, 3:56 PM CDT	Wind Advisory	LIX	Orleans, Saint Bernard, Saint John the Baptist, Saint Tammany	27 hr
May 20, 4:30 PM CDT	Special Marine Warning	LIX		90 min
May 20, 4:58 PM CDT	Special Weather Statement	LIX	Lafourche, Terrebonne	47 min
May 20, 5:16 PM CDT	Areal Flood Advisory	LIX	Assumption, Jefferson, Lafourche, Terrebonne	3 hr
May 20, 6:42 PM CDT	Flash Flood Warning	LIX	Ascension, East Baton Rouge, Iberville, Livingston, Saint Helena, West Baton Rouge	4 hr

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.