Alert archive / Oklahoma / Flash Flood Warnings in 2021

Flash Flood Warning 10, NWS Norman, OK

April 28, 2021Cleveland County, McClain County, Oklahoma

NWS Norman, OK issued this flash flood warning at Apr 28, 2021, 8:53 PM CDT for Cleveland County, McClain County, Oklahoma. It was in force for 3 hr. 2 reports 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: Apr 28, 2021, 8:53 PM CDT (01:53 UTC)
Expired: Apr 29, 2021, 12:00 AM CDT
In force: 3 hr
Issued by: NWS Norman, OK
Area: Storm-based polygon
Flood severity: None

Counties Cleveland County, OK, McClain County, OK

The radar

The Norman radar (KTLX), 22 km from the middle of the area, began a volume at 01:55 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
Apr 28, 9:05 PM CDT	FLASH FLOOD	4 Wnw Norman, OK	WATER RESCUE IN A VEHICLE.
Apr 28, 9:10 PM CDT	FLASH FLOOD	Norman, OK	HALF A DOZEN CLOSED STREETS FROM FLOODING, MOSTLY ON NORTHWEST SIDE OF TOWN.

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

The nearest sounding before it

Fort Worth, TX (KFWD), launched 00:00Z, 1.9 hours before the alert went out and 272 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.

475 
WGUS54 KOUN 290153
FFWOUN
OKC027-087-290500-
/O.NEW.KOUN.FF.W.0010.210429T0153Z-210429T0500Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

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

The National Weather Service in Norman has issued a

* Flash Flood Warning for...
  Northwestern Cleveland County in central Oklahoma...
  Northwestern McClain County in central Oklahoma...

* Until midnight CDT.

* At 853 PM CDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. 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...
  Southern Oklahoma City, Norman, Moore, Newcastle and Goldsby.

This includes the following highways...
	Interstate 35 between mile markers 107 and 119.

Additional rainfall amounts of 1 to 2 inches are possible in the 
warned area.

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 3529 9757 3536 9749 3526 9733 3515 9746
      3525 9763

FLASH FLOOD...RADAR INDICATED

$$

Zwink

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, 8:56 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, 11:37 PM CDT	Flash Flood Warning	OUN	Carter, Johnston, Love, Marshall, Murray	3 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; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.