Alert archive / Louisiana / Flash Flood Warnings in 2021

Flash Flood Warning 121, NWS New Orleans, LA

September 15, 2021Orleans Parish, Saint Tammany Parish, Washington Parish, Louisiana

NWS New Orleans, LA issued this flash flood warning at Sep 15, 2021, 8:18 AM CDT for Orleans Parish, Saint Tammany Parish, Washington Parish, Louisiana. It was in force for 5 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
Sep 15, 2021, 8:18 AM CDT (13:18 UTC)
Expired
Sep 15, 2021, 1:15 PM CDT
In force
5 hr
Issued by
NWS New Orleans, LA
Area
Storm-based polygon
Flood severity
None

Counties Orleans Parish, LA, Saint Tammany Parish, LA, Washington Parish, LA

The nearest sounding before it

Slidell Radar S, LA (KSIL), launched 12:00Z, 1.3 hours before the alert went out and 24 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 2021-09-15Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 84 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 2021-09-15The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 120 square meters per square second.1939Sfc1 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
84 J/kg
Mixed-layer CIN
-69 J/kg
Mixed-layer LCL
695 m above ground
0-6 km bulk shear
15 kt
0-1 km storm-relative helicity
120 m²/s²
0-3 km storm-relative helicity
285 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

452 
WGUS54 KLIX 151318
FFWLIX
LAC071-103-117-151615-
/O.NEW.KLIX.FF.W.0121.210915T1318Z-210915T1615Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service New Orleans LA
818 AM CDT Wed Sep 15 2021

The National Weather Service in New Orleans has issued a

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

* Until 1115 AM CDT.

* At 818 AM CDT, trained weather spotters reported thunderstorms 
  producing heavy rain in Heavy rain ovenight and water covering 
  multiple roads. . Between 2 and 5.5 inches of rain have fallen. 
  The expected rainfall rate is 1 to 2 inches in 1 hour and 30 
  minutes. Additional rainfall amounts of 1 to 3 inches are possible 
  in the warned area. Flash flooding is ongoing or expected to begin 
  shortly. Heavy rain in combionation with debris and blocked 
  drainage areas is resulting in flash flooding across the parishes.

  HAZARD...Flash flooding caused by thunderstorms.

  SOURCE...Trained spotters reported.

  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...
  New Orleans, Slidell, Bogalusa, Covington, Franklinton, Pearl 
  River, Abita Springs, Varnado, Madisonville, Folsom, Sun, Bush, 
  Enon, Lacombe, Mount Herman, Pearlington, Angie and Slidell 
  Airport.

This includes the following Interstates...
	Interstate 10 in Louisiana between mile markers 261 and 273.
	Interstate 12 between mile markers 53 and 84.
	Interstate 59 in Louisiana between mile markers 1 and 11.

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 3074 9025 3091 9035 3100 9035 3100 8973
      3066 8985 3056 8980 3045 8968 3029 8965
      3018 8956 3019 8955 3016 8957 3018 8969
      3017 8969 3015 8963 3012 8965 3015 8975
      3016 8969 3026 8998 3037 9009 3036 9024

FLASH FLOOD...OBSERVED
EXPECTED RAINFALL...1-2 INCHES IN 1 HOUR AND 30 MINUTES

$$

CAB
3 follow-up statements
053 
WGUS54 KLIX 151605
FFWLIX
LAC071-103-117-151815-
/O.EXT.KLIX.FF.W.0121.000000T0000Z-210915T1815Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service New Orleans LA
1105 AM CDT Wed Sep 15 2021

The National Weather Service in New Orleans has extended the

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

* Until 115 PM CDT.

* At 1105 AM CDT, trained weather spotters reported thunderstorms 
  producing heavy rain in Heavy rain ovenight and water covering 
  multiple roads. . Between 2 and 5.5 inches of rain have fallen. 
  The expected rainfall rate is 1 to 2 inches in 1 hour and 30 
  minutes. Additional rainfall amounts of 1 to 3 inches are possible 
  in the warned area. Flash flooding is ongoing or expected to begin 
  shortly.

  HAZARD...Flash flooding caused by thunderstorms.

  SOURCE...Trained spotters reported.

  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...
  New Orleans, Slidell, Bogalusa, Covington, Franklinton, Pearl 
  River, Abita Springs, Varnado, Madisonville, Folsom, Sun, Bush, 
  Enon, Lacombe, Mount Herman, Pearlington, Angie and Slidell 
  Airport.

This includes the following Interstates...
	Interstate 10 in Louisiana between mile markers 261 and 272.
	Interstate 12 between mile markers 53 and 84.
	Interstate 59 in Louisiana between mile markers 1 and 11.

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 3074 9025 3091 9035 3100 9035 3100 8973
      3066 8985 3056 8980 3045 8968 3029 8965
      3018 8956 3019 8955 3016 8957 3018 8969
      3017 8969 3015 8963 3012 8965 3015 8975
      3016 8969 3026 8998 3037 9009 3036 9024

FLASH FLOOD...OBSERVED
EXPECTED RAINFALL...1-2 INCHES IN 1 HOUR AND 30 MINUTES

$$
780 
WGUS74 KLIX 151621
FFSLIX

Flash Flood Statement
National Weather Service New Orleans LA
1121 AM CDT Wed Sep 15 2021

LAC071-151631-
/O.CAN.KLIX.FF.W.0121.000000T0000Z-210915T1815Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Orleans LA-
1121 AM CDT Wed Sep 15 2021

...FLASH FLOOD WARNING IS CANCELLED FOR NORTHERN ORLEANS PARISH...

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

A Flash Flood Watch remains in effect until 700 AM CDT Thursday for 
portions of southeast Louisiana and Mississippi.

LAT...LON 3074 9025 3081 9029 3089 9032 3091 9035
      3100 9035 3100 8973 3079 8981 3079 8982
      3078 8983 3075 8983 3075 8982 3073 8983
      3071 8985 3070 8984 3066 8985 3056 8980
      3037 9009 3039 9019 3037 9024

$$

LAC103-117-151815-
/O.CON.KLIX.FF.W.0121.000000T0000Z-210915T1815Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
St. Tammany LA-Washington LA-
1121 AM CDT Wed Sep 15 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 115 PM CDT THIS 
AFTERNOON FOR NORTHWESTERN ST. TAMMANY AND WASHINGTON PARISHES...

At 1121 AM CDT, Doppler radar indicated thunderstorms producing 
heavy and water covering multiple roads. Between 3 and 6 inches of 
rain have fallen. Additional rainfall amounts of 1 to 2 inches are 
possible in the warned area. Flash flooding is already occurring.

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...
  Bogalusa, Covington, Franklinton, Abita Springs, Varnado, 
  Madisonville, Folsom, Sun, Enon, Bush, Mount Herman and Angie.

This includes the following Interstates...
	Interstate 12 between mile markers 53 and 66.

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 3074 9025 3081 9029 3089 9032 3091 9035
      3100 9035 3100 8973 3079 8981 3079 8982
      3078 8983 3075 8983 3075 8982 3073 8983
      3071 8985 3070 8984 3066 8985 3056 8980
      3037 9009 3039 9019 3037 9024

FLASH FLOOD...RADAR INDICATED

$$

MEFFER
594 
WGUS74 KLIX 151809
FFSLIX

Flash Flood Statement
National Weather Service New Orleans LA
109 PM CDT Wed Sep 15 2021

LAC103-117-151819-
/O.EXP.KLIX.FF.W.0121.000000T0000Z-210915T1815Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
St. Tammany LA-Washington LA-
109 PM CDT Wed Sep 15 2021

...FLASH FLOOD WARNING WILL EXPIRE AT 115 PM CDT THIS AFTERNOON FOR 
NORTHWESTERN ST. TAMMANY AND WASHINGTON PARISHES...

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

A Flash Flood Watch remains in effect until 700 AM CDT Thursday for 
portions of southeast Louisiana and Mississippi.

LAT...LON 3074 9025 3081 9029 3089 9032 3091 9035
      3100 9035 3100 8973 3079 8981 3079 8982
      3078 8983 3075 8983 3075 8982 3073 8983
      3071 8985 3070 8984 3066 8985 3056 8980
      3037 9009 3039 9019 3037 9024

$$

The office that day

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

IssuedProductOfficeCountiesLasted
Sep 14, 10:20 PM CDTSpecial Weather StatementLIXTerrebonne55 min
Sep 14, 10:38 PM CDTTornado WarningLIXTerrebonne37 min
Sep 15, 2:33 AM CDTAreal Flood AdvisoryLIXJefferson, Orleans, Plaquemines, Saint Bernard, Saint Charles117 min
Sep 15, 3:12 AM CDTAreal Flood AdvisoryLIXTangipahoa2 hr
Sep 15, 3:29 AM CDTTornado WarningLIXPlaquemines, Saint Bernard31 min
Sep 15, 4:09 AM CDTTornado WarningLIXOrleans, Saint Bernard13 min
Sep 15, 4:32 AM CDTSpecial Marine WarningLIX58 min
Sep 15, 5:21 AM CDTFlash Flood WarningLIXSaint Tammany, Tangipahoa, Washington3 hr
Sep 15, 6:22 AM CDTTornado WarningLIXSaint Tammany23 min
Sep 15, 7:14 AM CDTSpecial Marine WarningLIX91 min
Sep 15, 7:45 AM CDTFlash Flood WarningLIXWashington3 hr
Sep 15, 7:55 AM CDTRiver Flood WarningLIXSaint Tammany4 days
Sep 15, 7:55 AM CDTRiver Flood WarningLIXSaint Tammany49 hr
Sep 15, 8:28 AM CDTSpecial Marine WarningLIX62 min
Sep 15, 8:37 AM CDTRiver Flood WarningLIXTangipahoa28 hr
Sep 15, 8:50 AM CDTSpecial Marine WarningLIX55 min
Sep 15, 8:59 AM CDTRiver Flood WarningLIXEast Baton Rouge28 hr
Sep 15, 9:02 AM CDTRiver Flood WarningLIXSaint Tammany6 days
Sep 15, 9:04 AM CDTRiver Flood WarningLIXSaint Helena4 days
Sep 15, 9:08 AM CDTRiver Flood WarningLIXSaint Tammany, Washington5 days
Sep 15, 9:08 AM CDTRiver Flood WarningLIXSaint Tammany7 days
Sep 15, 9:59 AM CDTSpecial Marine WarningLIX61 min
Sep 15, 3:39 PM CDTRiver Flood WarningLIXLivingston42 hr
Sep 15, 3:39 PM CDTRiver Flood WarningLIXWashington21 hr
Sep 15, 6:13 PM CDTAreal Flood AdvisoryLIXAscension, East Baton Rouge, Iberville, Livingston, West Baton Rouge3 hr

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.