Alert archive / Louisiana / Flash Flood Warnings in 2021

Flash Flood Warning 71, NWS New Orleans, LA

July 7, 2021Saint Tammany Parish, Louisiana

NWS New Orleans, LA issued this flash flood warning at Jul 7, 2021, 2:54 AM CDT for Saint Tammany 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: Jul 7, 2021, 2:54 AM CDT (07:54 UTC)
Expired: Jul 7, 2021, 6:00 AM CDT
In force: 3 hr
Issued by: NWS New Orleans, LA
Area: Storm-based polygon
Flood severity: None

County Saint Tammany Parish, LA

What was reported inside it

Time	Report	Where	Remark
Jul 7, 4:15 AM CDT	FLASH FLOOD	2 N Madisonville, LA	SEVERAL STREETS FLOODED NEAR HWY 21 AND DUMMYLINE RD.

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, 7.9 hours before the alert went out and 41 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: 1996 J/kg
Mixed-layer CIN: -2 J/kg
Mixed-layer LCL: 636 m above ground
0-6 km bulk shear: 12 kt
0-1 km storm-relative helicity: 66 m²/s²
0-3 km storm-relative helicity: 43 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

618 
WGUS54 KLIX 070754
FFWLIX
LAC103-071100-
/O.NEW.KLIX.FF.W.0071.210707T0754Z-210707T1100Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service New Orleans LA
254 AM CDT Wed Jul 7 2021

The National Weather Service in New Orleans has issued a

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

* Until 600 AM CDT.

* At 254 AM CDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Between 1 and 2.5 inches of 
  rain have fallen. The expected rainfall rate is 2 to 3 inches in 1 
  hour. Additional rainfall amounts of 2 to 5 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...
  Covington, Abita Springs and Madisonville.

This includes the following Interstates...
	Interstate 12 between mile markers 56 and 68.

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 3040 9023 3053 9017 3049 8999 3032 9002
      3033 9004 3034 9005 3035 9005 3035 9006
      3037 9009 3037 9012 3038 9016

FLASH FLOOD...RADAR INDICATED
EXPECTED RAINFALL...2-3 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
Jul 6, 9:18 PM CDT	Areal Flood Advisory	LIX	Saint Tammany, Washington	2 hr
Jul 7, 2:51 AM CDT	Areal Flood Advisory	LIX	Saint Tammany	3 min
Jul 7, 10:39 AM CDT	Special Marine Warning	LIX		66 min
Jul 7, 5:19 PM CDT	Severe Thunderstorm Warning	LIX	Lafourche	26 min

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.