Alert archive / Louisiana / Flash Flood Warnings in 2021

Flash Flood Warning 10, NWS Shreveport, LA

May 20, 20214 parishes in Louisiana

NWS Shreveport, LA issued this flash flood warning at May 20, 2021, 9:32 PM CDT for 4 parishes in Louisiana. It was in force for 88 min. 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
May 20, 2021, 9:32 PM CDT (02:32 UTC)
Expired
May 20, 2021, 11:00 PM CDT
In force
88 min
Issued by
NWS Shreveport, LA
Area
Storm-based polygon
Flood severity
None

Counties De Soto Parish, LA, Natchitoches Parish, LA, Red River Parish, LA, Sabine Parish, LA

The radar

The Ft Polk radar (KPOE), 47 km from the middle of the area, began a volume at 02:33 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

TimeReportWhereRemark
May 20, 10:12 PM CDTFLASH FLOOD2 Nne Many, LAHIGH WATER REPORTED ON PETTY ROAD NORTHEAST OF MANY, LOUISIANA.

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 00:00Z, 2.5 hours before the alert went out and 118 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, Shreveport, LA at 00:00Z on 2021-05-21Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 198 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, Shreveport, LA at 00:00Z on 2021-05-21The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 140 square meters per square second.19395878Sfc1 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
198 J/kg
Mixed-layer CIN
-14 J/kg
Mixed-layer LCL
844 m above ground
0-6 km bulk shear
38 kt
0-1 km storm-relative helicity
140 m²/s²
0-3 km storm-relative helicity
204 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.6

Open this sounding in Storm Lab

The text

As transmitted.

441 
WGUS54 KSHV 210232
FFWSHV
LAC031-069-081-085-210400-
/O.NEW.KSHV.FF.W.0010.210521T0232Z-210521T0400Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Shreveport LA
932 PM CDT Thu May 20 2021

The National Weather Service in Shreveport has issued a

* Flash Flood Warning for...
  Southeastern De Soto Parish in northwestern Louisiana...
  Southwestern Natchitoches Parish in northwestern Louisiana...
  Red River Parish in northwestern Louisiana...
  Eastern Sabine Parish in northwestern Louisiana...

* Until 1100 PM CDT.

* At 932 PM CDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Between 1 and 3 inches of rain 
  have fallen. Flash flooding is ongoing or expected to begin 
  shortly.

  HAZARD...Flash flooding caused by thunderstorms.

  SOURCE...Doppler radar.

  IMPACT...Flooding of small creeks and streams, urban areas,
           highways, streets and underpasses as well as other
           drainage and low lying areas.

* Some locations that will experience flash flooding include...
  Natchitoches, Many, Coushatta, Allen, Pleasant Hill, Florien, 
  Provencal, Natchez, Martin, Hall Summit, Fisher, Edgefield, 
  Robeline, Powhatan, Marthaville, Hagewood, Ajax, Lake End, Belmont 
  and Hanna.

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 3222 9370 3222 9328 3139 9289 3139 9291
      3137 9291 3137 9295 3135 9295 3135 9298
      3136 9299 3136 9303 3136 9339 3128 9344
      3128 9348

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

$$

13

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; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.