Alert archive / Louisiana / Flash Flood Warnings in 2021

Flash Flood Warning 91, NWS New Orleans, LA

August 29, 2021Saint Tammany Parish, Louisiana

NWS New Orleans, LA issued this flash flood warning at Aug 29, 2021, 6:21 PM CDT for Saint Tammany Parish, Louisiana. It was in force for 16 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, 6:21 PM CDT (23:21 UTC)
Expired
Aug 30, 2021, 10:45 AM CDT
In force
16 hr
Issued by
NWS New Orleans, LA
Area
Storm-based polygon
Flood severity
None

County Saint Tammany Parish, LA

The nearest sounding before it

Slidell Radar S, LA (KSIL), launched 12:00Z, 11.4 hours before the alert went out and 21 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.

966 
WGUS54 KLIX 292321
FFWLIX
LAC103-300515-
/O.NEW.KLIX.FF.W.0091.210829T2321Z-210830T0515Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

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

The National Weather Service in New Orleans has issued a

* Flash Flood Warning for...
  St. Tammany Parish in southeastern Louisiana...

* Until 1215 AM CDT.

* At 621 PM CDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Between 1.5 and 4 inches of 
  rain have fallen. Additional rainfall amounts of 3 to 6 inches are 
  possible in the warned area through midnight. Flash flooding is 
  ongoing or expected to begin shortly.

  HAZARD...Flash flooding caused by heavy rainfall from hurricane
           rainbands.

  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...
  Slidell, Covington, Pearl River, Abita Springs, Madisonville, 
  Lacombe and Slidell Airport.

This includes the following Interstates...
	Interstate 10 in Louisiana between mile markers 261 and 271.
	Interstate 12 between mile markers 53 and 84.
	Interstate 59 in Louisiana between mile markers 1 and 9.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3026 8967 3019 8969 3018 8972 3023 8985
      3025 8986 3027 8994 3035 9006 3040 9024
      3061 9025 3060 9007 3054 8982 3044 8971

FLASH FLOOD...RADAR INDICATED

$$

TD
4 follow-up statements
243 
WGUS54 KLIX 300122
FFWLIX
LAC103-300715-
/O.EXT.KLIX.FF.W.0091.000000T0000Z-210830T0715Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

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

The National Weather Service in New Orleans has extended the

* Flash Flood Warning for...
  St. Tammany Parish in southeastern Louisiana...

* Until 215 AM CDT.

* At 822 PM CDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Between 3 and 6.5 inches of 
  rain have fallen. Additional rainfall amounts of 3 to 6 inches are 
  possible in 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...
  Slidell, Covington, Pearl River, Abita Springs, Madisonville, 
  Lacombe and Slidell Airport.

This includes the following Interstates...
	Interstate 10 in Louisiana between mile markers 261 and 271.
	Interstate 12 between mile markers 53 and 84.
	Interstate 59 in Louisiana between mile markers 1 and 9.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3026 8967 3019 8969 3018 8972 3023 8985
      3025 8986 3027 8994 3035 9006 3040 9024
      3061 9025 3060 9007 3054 8982 3044 8971

FLASH FLOOD...RADAR INDICATED

$$

CAB
611 
WGUS54 KLIX 300509
FFWLIX
LAC103-300915-
/O.EXT.KLIX.FF.W.0091.000000T0000Z-210830T0915Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service New Orleans LA
1209 AM CDT Mon Aug 30 2021

The National Weather Service in New Orleans has extended the

* Flash Flood Warning for...
  St. Tammany Parish in southeastern Louisiana...

* Until 415 AM CDT.

* At 1209 AM CDT, Doppler radar and automated rain gauges indicated 
  thunderstorms producing heavy rain across the warned area. Between 
  5 and 11 inches of rain have fallen. Additional rainfall amounts 
  of 2 to 4 inches are possible in the warned area. Combination of 
  surge and heavy rain is leading to significant flash flooding 
  concerns around Covington, Mandeville, and Madisonville. Flash 
  flooding due to heavy rain is expected around Slidell.

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

  SOURCE...Radar and automated gauges.

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

* Some locations that will experience flash flooding include...
  Slidell, Covington, Pearl River, Abita Springs, Madisonville, 
  Lacombe and Slidell Airport.

This includes the following Interstates...
	Interstate 10 in Louisiana between mile markers 261 and 271.
	Interstate 12 between mile markers 53 and 84.
	Interstate 59 in Louisiana between mile markers 1 and 9.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Be especially cautious at night when it is harder to recognize the 
dangers of flooding.

&&

LAT...LON 3026 8967 3019 8969 3018 8972 3023 8985
      3025 8986 3027 8994 3035 9006 3040 9024
      3061 9025 3060 9007 3054 8982 3044 8971

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

$$

CAB
567 
WGUS54 KLIX 300908
FFWLIX
LAC103-301245-
/O.EXT.KLIX.FF.W.0091.000000T0000Z-210830T1245Z/
/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
408 AM CDT Mon Aug 30 2021

The National Weather Service in New Orleans has extended the

* Flash Flood Warning for...
  St. Tammany Parish in southeastern Louisiana...

* Until 745 AM CDT.

* At 408 AM CDT, Doppler radar and automated rain gauges indicated 
  thunderstorms producing heavy rain across are ending across the 
  area. Between 7 and 15 inches of rain have fallen. Additional 
  rainfall amounts of 1 to 2 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 and automated gauges.

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

* Some locations that will experience flash flooding include...
  Slidell, Covington, Pearl River, Abita Springs, Madisonville, 
  Lacombe and Slidell Airport.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Be especially cautious at night when it is harder to recognize the 
dangers of flooding.

&&

LAT...LON 3026 8967 3019 8969 3018 8972 3023 8985
      3025 8986 3027 8994 3035 9006 3040 9024
      3061 9025 3060 9007 3054 8982 3044 8971

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

$$
279 
WGUS54 KLIX 301235
FFWLIX
LAC103-301545-
/O.EXT.KLIX.FF.W.0091.000000T0000Z-210830T1545Z/
/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
735 AM CDT Mon Aug 30 2021

The National Weather Service in New Orleans has extended the

* Flash Flood Warning for...
  St. Tammany Parish in southeastern Louisiana...

* Until 1045 AM CDT.

* At 735 AM CDT, Doppler radar indicated that the heavy rainfall has 
  ended across the area, however river gauges continue to indicate 
  rising waters in the area. Between 7 and 15 inches of rain have 
  fallen. Flash flooding is already occurring.

  HAZARD...Life threatening flash flooding. Heavy rain producing
           flash flooding.

  SOURCE...Radar and automated gauges.

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

* Some locations that will experience flash flooding include...
  Slidell, Covington, Pearl River, Abita Springs, Madisonville, 
  Lacombe and Slidell Airport.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Be especially cautious at night when it is harder to recognize the 
dangers of flooding.

&&

LAT...LON 3026 8967 3019 8969 3018 8972 3023 8985
      3025 8986 3027 8994 3035 9006 3040 9024
      3061 9025 3060 9007 3054 8982 3044 8971

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

$$

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, 3:39 PM CDTFlash Flood WarningLIXLafourche, Terrebonne7 hr
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, 6:25 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.