Alert archive / Louisiana / Flash Flood Warnings in 2021

Flash Flood Warning 46, NWS Lake Charles, LA

July 20, 2021Acadia Parish, Jefferson Davis Parish, Saint Landry Parish, Louisiana

NWS Lake Charles, LA issued this flash flood warning at Jul 20, 2021, 10:33 AM CDT for Acadia Parish, Jefferson Davis Parish, Saint Landry 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 20, 2021, 10:33 AM CDT (15:33 UTC)
Expired: Jul 20, 2021, 1:30 PM CDT
In force: 3 hr
Issued by: NWS Lake Charles, LA
Area: Storm-based polygon
Flood severity: None

Counties Acadia Parish, LA, Jefferson Davis Parish, LA, Saint Landry Parish, LA

The radar

The Lake Charles radar (KLCH), 75 km from the middle of the area, began a volume at 15:34 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

What was reported inside it

Time	Report	Where	Remark
Jul 20, 11:50 AM CDT	FLASH FLOOD	5 W Iota, LA	SOCIAL MEDIA POST FROM ACADIA PARISH SHERIFFS OFFICE WITH A LIST OF NUMEROUS ROADS WITH HIGH WATER AND SOME IMPASSABLE IN THE WESTERN PORTION OF THE PARISH AND AROUND THE CITY OF IOTA. TIME OF WHEN FLOODING STARTED IS ESTIMATED FROM FLASH DATA.

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

The nearest sounding before it

Shreveport, LA (KSHV), launched 12:00Z, 3.6 hours before the alert went out and 256 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: 699 J/kg
Mixed-layer CIN: -14 J/kg
Mixed-layer LCL: 642 m above ground
0-6 km bulk shear: 10 kt
0-1 km storm-relative helicity: -27 m²/s²
0-3 km storm-relative helicity: -15 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

477 
WGUS54 KLCH 201533
FFWLCH
LAC001-053-097-201830-
/O.NEW.KLCH.FF.W.0046.210720T1533Z-210720T1830Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Lake Charles LA
1033 AM CDT Tue Jul 20 2021

The National Weather Service in Lake Charles has issued a

* Flash Flood Warning for...
  West Central St. Landry Parish in central Louisiana...
  Northwestern Acadia Parish in southwestern Louisiana...
  East Central Jefferson Davis Parish in southwestern Louisiana...

* Until 130 PM CDT.

* At 1033 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 2 to 3 inches in 1 
  hour. 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...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...
  Eunice, Iota, Mowata, Maxie and Hathaway.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3028 9270 3039 9269 3045 9262 3048 9256
      3048 9249 3050 9248 3050 9246 3052 9246
      3054 9244 3054 9233 3037 9232 3027 9247

FLASH FLOOD...RADAR INDICATED
EXPECTED RAINFALL...2-3 INCHES IN 1 HOUR

$$

Warthen

The office that day

Everything else NWS Lake Charles, LA issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jul 19, 11:39 PM CDT	Special Marine Warning	LCH		36 min
Jul 20, 2:06 AM CDT	Special Weather Statement	LCH	Lafayette	69 min
Jul 20, 2:37 AM CDT	Special Weather Statement	LCH	Beauregard, Calcasieu	53 min
Jul 20, 3:18 AM CDT	Special Weather Statement	LCH	Calcasieu	42 min
Jul 20, 3:41 AM CDT	Severe Thunderstorm Warning	LCH	Calcasieu, Jefferson Davis	30 min
Jul 20, 9:15 AM CDT	River Flood Warning	LCH	Lafayette, Saint Martin, Vermilion	36 hr
Jul 20, 9:15 AM CDT	River Flood Warning	LCH	Acadia, Evangeline, Saint Landry	71 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; radar from the NEXRAD Level II archive.