Alert archive / Louisiana / Flash Flood Warnings in 2021

Flash Flood Warning 117, NWS New Orleans, LA

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

NWS New Orleans, LA issued this flash flood warning at Sep 15, 2021, 5:21 AM CDT for Saint Tammany Parish, Tangipahoa Parish, Washington Parish, Louisiana. It was in force for 3 hr. 1 report came from inside the area while it was in force.

The area

The outline as issued, with what was reported inside it.

The facts

Issued: Sep 15, 2021, 5:21 AM CDT (10:21 UTC)
Expired: Sep 15, 2021, 8:30 AM CDT
In force: 3 hr
Issued by: NWS New Orleans, LA
Area: Storm-based polygon
Flood severity: None

Counties Saint Tammany Parish, LA, Tangipahoa Parish, LA, Washington Parish, LA

What was reported inside it

Time	Report	Where	Remark
Sep 15, 7:15 AM CDT	FLASH FLOOD	4 S Bogalusa, LA	ROADS FLOODED AROUND THE LEES CREEK AREA. RELAYED VIA SOCIAL MEDIA.

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

The nearest sounding before it

Slidell Radar S, LA (KSIL), launched 00:00Z, 10.4 hours before the alert went out and 85 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: 136 J/kg
Mixed-layer CIN: -10 J/kg
Mixed-layer LCL: 589 m above ground
0-6 km bulk shear: 31 kt
0-1 km storm-relative helicity: 29 m²/s²
0-3 km storm-relative helicity: 181 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.1

Open this sounding in Storm Lab

The text

As transmitted.

501 
WGUS54 KLIX 151021
FFWLIX
LAC103-105-117-151330-
/O.NEW.KLIX.FF.W.0117.210915T1021Z-210915T1330Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

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

The National Weather Service in New Orleans has issued a

* Flash Flood Warning for...
  North Central St. Tammany Parish in southeastern Louisiana...
  Northeastern Tangipahoa Parish in southeastern Louisiana...
  Washington Parish in southeastern Louisiana...

* Until 830 AM CDT.

* At 521 AM CDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Between 2 and 3 inches of rain 
  have fallen. The expected rainfall rate is 1 to 2 inches in 1 
  hour. Additional rainfall amounts of 2 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...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, Franklinton, Varnado, Sun, Enon, Bush and Mount Herman.

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 3096 9037 3100 9040 3100 9039 3100 9038
      3100 9037 3100 9026 3099 8991 3089 8978
      3078 8983 3075 8984 3042 8991 3093 9035

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

$$

TE

The office that day

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

Issued	Product	Office	Counties	Lasted
Sep 14, 10:20 PM CDT	Special Weather Statement	LIX	Terrebonne	55 min
Sep 14, 10:38 PM CDT	Tornado Warning	LIX	Terrebonne	37 min
Sep 15, 2:33 AM CDT	Areal Flood Advisory	LIX	Jefferson, Orleans, Plaquemines, Saint Bernard, Saint Charles	117 min
Sep 15, 3:12 AM CDT	Areal Flood Advisory	LIX	Tangipahoa	2 hr
Sep 15, 3:29 AM CDT	Tornado Warning	LIX	Plaquemines, Saint Bernard	31 min
Sep 15, 4:09 AM CDT	Tornado Warning	LIX	Orleans, Saint Bernard	13 min
Sep 15, 4:32 AM CDT	Special Marine Warning	LIX		58 min
Sep 15, 6:22 AM CDT	Tornado Warning	LIX	Saint Tammany	23 min
Sep 15, 7:14 AM CDT	Special Marine Warning	LIX		91 min
Sep 15, 7:45 AM CDT	Flash Flood Warning	LIX	Washington	3 hr
Sep 15, 7:55 AM CDT	River Flood Warning	LIX	Saint Tammany	4 days
Sep 15, 7:55 AM CDT	River Flood Warning	LIX	Saint Tammany	49 hr
Sep 15, 8:18 AM CDT	Flash Flood Warning	LIX	Orleans, Saint Tammany, Washington	5 hr
Sep 15, 8:28 AM CDT	Special Marine Warning	LIX		62 min
Sep 15, 8:37 AM CDT	River Flood Warning	LIX	Tangipahoa	28 hr
Sep 15, 8:50 AM CDT	Special Marine Warning	LIX		55 min
Sep 15, 8:59 AM CDT	River Flood Warning	LIX	East Baton Rouge	28 hr
Sep 15, 9:02 AM CDT	River Flood Warning	LIX	Saint Tammany	6 days
Sep 15, 9:04 AM CDT	River Flood Warning	LIX	Saint Helena	4 days
Sep 15, 9:08 AM CDT	River Flood Warning	LIX	Saint Tammany, Washington	5 days
Sep 15, 9:08 AM CDT	River Flood Warning	LIX	Saint Tammany	7 days
Sep 15, 9:59 AM CDT	Special Marine Warning	LIX		61 min
Sep 15, 3:39 PM CDT	River Flood Warning	LIX	Livingston	42 hr
Sep 15, 3:39 PM CDT	River Flood Warning	LIX	Washington	21 hr
Sep 15, 6:13 PM CDT	Areal Flood Advisory	LIX	Ascension, East Baton Rouge, Iberville, Livingston, West Baton Rouge	3 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; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive.