Alert archive / Oklahoma / Flash Flood Warnings in 2021

Flash Flood Warning 11, NWS Norman, OK

April 28, 20215 counties in Oklahoma

NWS Norman, OK issued this flash flood warning at Apr 28, 2021, 11:37 PM CDT for 5 counties in Oklahoma. It was in force for 3 hr. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued: Apr 28, 2021, 11:37 PM CDT (04:37 UTC)
Expired: Apr 29, 2021, 2:45 AM CDT
In force: 3 hr
Issued by: NWS Norman, OK
Area: Storm-based polygon
Flood severity: None

Counties Carter County, OK, Johnston County, OK, Love County, OK, Marshall County, OK, Murray County, OK

The radar

The Norman radar (KTLX), 131 km from the middle of the area, began a volume at 04:37 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.

The nearest sounding before it

Fort Worth, TX (KFWD), launched 00:00Z, 4.6 hours before the alert went out and 150 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: 1526 J/kg
Mixed-layer CIN: -11 J/kg
Mixed-layer LCL: 1058 m above ground
0-6 km bulk shear: 73 kt
0-1 km storm-relative helicity: 191 m²/s²
0-3 km storm-relative helicity: 154 m²/s²
Significant tornado parameter: 2.2
Supercell composite: 9.4

Open this sounding in Storm Lab

The text

As transmitted.

342 
WGUS54 KOUN 290437
FFWOUN
OKC019-069-085-095-099-290745-
/O.NEW.KOUN.FF.W.0011.210429T0437Z-210429T0745Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Norman OK
1137 PM CDT Wed Apr 28 2021

The National Weather Service in Norman has issued a

* Flash Flood Warning for...
  West Central Johnston County in southeastern Oklahoma...
  Northwestern Marshall County in southeastern Oklahoma...
  Southeastern Carter County in southern Oklahoma...
  North Central Love County in southern Oklahoma...
  Southeastern Murray County in southern Oklahoma...

* Until 245 AM CDT.

* At 1137 PM CDT, Doppler radar and automated rain gauges indicated 
  thunderstorms producing heavy rain across the warned area. Between 
  1 and 2 inches of rain have fallen. Flash flooding is ongoing or 
  expected to begin shortly.

  HAZARD...Flash flooding caused by thunderstorms.

  SOURCE...Doppler radar and automated gauges.

  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...
  Ardmore, Lone Grove, Dickson, Mannsville, Gene Autry, Lake Murray 
  and Overbrook.

This includes the following highways...
	Interstate 35 between mile markers 23 and 35.

Additional rainfall amounts of 0.5 to 1 inch are possible in the 
warned area.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3414 9727 3420 9721 3439 9686 3427 9679
      3417 9689 3401 9706 3404 9718

FLASH FLOOD...RADAR AND GAUGE INDICATED
EXPECTED RAINFALL...1-1.5 INCHES IN 1 HOUR 

$$

03

1 follow-up statement

928 
WGUS74 KOUN 290602
FFSOUN

Flash Flood Statement
National Weather Service Norman OK
102 AM CDT Thu Apr 29 2021

OKC019-069-085-095-099-290745-
/O.CON.KOUN.FF.W.0011.000000T0000Z-210429T0745Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Carter OK-Johnston OK-Love OK-Marshall OK-Murray OK-
102 AM CDT Thu Apr 29 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 245 AM CDT EARLY THIS 
MORNING FOR WEST CENTRAL JOHNSTON, NORTHWESTERN MARSHALL, 
SOUTHEASTERN CARTER, NORTH CENTRAL LOVE AND SOUTHEASTERN MURRAY 
COUNTIES...

At 102 AM CDT, Doppler radar and automated rain gauges indicated 
thunderstorms produced heavy rain across the warned area. Between 1 
and 2 inches of rain have fallen. Flash flooding is ongoing or 
expected to begin shortly.

HAZARD...Flash flooding caused by thunderstorms.

SOURCE...Doppler radar and automated gauges.

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...
  Ardmore, Lone Grove, Dickson, Mannsville, Gene Autry, Lake Murray 
  and Overbrook.

This includes the following highways...
	Interstate 35 between mile markers 23 and 35.

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.

Please report flooding to your local law enforcement agency when you 
can do so safely.

&&

LAT...LON 3414 9727 3420 9721 3438 9688 3439 9686
      3427 9679 3410 9697 3401 9706 3404 9718

FLASH FLOOD...RADAR AND GAUGE INDICATED

$$

03

The office that day

Everything else NWS Norman, OK issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Apr 28, 7:15 PM CDT	Severe Thunderstorm Warning	OUN	Caddo	45 min
Apr 28, 7:55 PM CDT	Severe Thunderstorm Warning	OUN	Caddo, Grady	50 min
Apr 28, 8:28 PM CDT	Severe Thunderstorm Warning	OUN	Cleveland, Grady, McClain	47 min
Apr 28, 8:53 PM CDT	Flash Flood Warning	OUN	Cleveland, McClain	3 hr
Apr 28, 8:56 PM CDT	Severe Thunderstorm Warning	OUN	Cleveland, Lincoln, McClain, Oklahoma, Pottawatomie	49 min
Apr 28, 9:13 PM CDT	Areal Flood Advisory	OUN	Cleveland, Grady, McClain, Pottawatomie	3 hr
Apr 28, 9:41 PM CDT	Severe Thunderstorm Warning	OUN	Pottawatomie, Seminole	49 min
Apr 28, 9:45 PM CDT	Special Weather Statement	OUN	Stephens	45 min
Apr 28, 10:23 PM CDT	Special Weather Statement	OUN	Love	37 min
Apr 28, 10:53 PM CDT	Special Weather Statement	OUN	Carter, Hughes, Love, Murray, Pontotoc	37 min
Apr 28, 10:57 PM CDT	Areal Flood Advisory	OUN	Carter, Coal, Hughes, Johnston, Love, Marshall and 2 more	5 hr
Apr 28, 11:19 PM CDT	River Flood Advisory	OUN	Pottawatomie, Seminole	9 hr
Apr 28, 11:24 PM CDT	River Flood Advisory	OUN	Hughes	9 hr
Apr 28, 11:51 PM CDT	River Flood Warning	OUN	Jackson, Kiowa, Tillman	7 hr
Apr 28, 11:52 PM CDT	River Flood Warning	OUN	Atoka	3 days
Apr 28, 11:52 PM CDT	Special Weather Statement	OUN	Coal, Johnston, Love, Marshall	23 min
Apr 28, 11:53 PM CDT	River Flood Advisory	OUN	Cotton	10 hr
Apr 29, 12:06 AM CDT	Areal Flood Advisory	OUN	Atoka, Bryan, Coal, Hughes, Johnston, Marshall	5 hr
Apr 29, 12:23 AM CDT	Special Weather Statement	OUN	Atoka, Bryan	37 min
Apr 29, 6:29 AM CDT	River Flood Advisory	OUN	Bryan	11 hr

Nearby

Flash Flood Warnings in Oklahoma, 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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.