Alert archive / Oklahoma / Flash Flood Warnings in 2021

Flash Flood Warning 9, NWS Shreveport, LA

May 20, 2021McCurtain County, Oklahoma

NWS Shreveport, LA issued this flash flood warning at May 20, 2021, 7:50 PM CDT for McCurtain County, Oklahoma. It was in force for 100 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, 7:50 PM CDT (00:50 UTC)
Expired
May 20, 2021, 9:30 PM CDT
In force
100 min
Issued by
NWS Shreveport, LA
Area
Storm-based polygon
Flood severity
None

County McCurtain County, OK

The radar

The Western Arkansas radar (KSRX), 121 km from the middle of the area, began a volume at 00:53 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, 8:16 PM CDTFLASH FLOOD3 W Hochatown, OKPARK RANGERS REPORT FLOODED ROADWAYS IN AND AROUND HOCHATOWN STATE PARK.

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, 0.8 hours before the alert went out and 215 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.

103 
WGUS54 KSHV 210050
FFWSHV
OKC089-210230-
/O.NEW.KSHV.FF.W.0009.210521T0050Z-210521T0230Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

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

The National Weather Service in Shreveport has issued a

* Flash Flood Warning for...
  Northeastern McCurtain County in southeastern Oklahoma...

* Until 930 PM CDT.

* At 750 PM CDT, Trained weather spotters reported thunderstorms 
  producing heavy rain across the warned area. Between 2 and 4 
  inches of rain have fallen. Flash flooding is already occurring.

  HAZARD...Flash flooding caused by thunderstorms.

  SOURCE...Trained spotters.

  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...
  Idabel, Broken Bow, Haworth, Hochatown, Eagletown, Sherwood, 
  Goodwater, Cerrogordo, Watson, Shinewell and Smithville.

While heavy rainfall is trying to move out of the area, runoff from 
previous heavy rainfall is likely not complete.

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.

Excessive runoff from heavy rainfall will cause flooding of small 
creeks and streams, country roads, farmland, and other low lying 
spots.

&&

LAT...LON 3442 9481 3386 9482 3382 9449 3447 9450
      3446 9481

FLASH FLOOD...OBSERVED
EXPECTED RAINFALL...0.5-1 INCH IN 1 HOUR AND 30 MINUTES

$$

13

Nearby

Flash Flood Warnings in Oklahoma, 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.