Alert archive / Oklahoma / Flash Flood Warnings in 2021

Flash Flood Warning 25, NWS Norman, OK

May 31, 2021Greer County, Harmon County, Oklahoma

NWS Norman, OK issued this flash flood warning at May 31, 2021, 4:07 AM CDT for Greer County, Harmon County, Oklahoma. It was in force for 5 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: May 31, 2021, 4:07 AM CDT (09:07 UTC)
Expired: May 31, 2021, 9:00 AM CDT
In force: 5 hr
Issued by: NWS Norman, OK
Area: Storm-based polygon
Flood severity: None

Counties Greer County, OK, Harmon County, OK

The radar

The Altus AFB radar (KFDR), 77 km from the middle of the area, began a volume at 09:10 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

Amarillo Airport, TX (KAMA), launched 00:00Z, 9.1 hours before the alert went out and 195 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: 436 J/kg
Mixed-layer CIN: -34 J/kg
Mixed-layer LCL: 1025 m above ground
0-6 km bulk shear: 26 kt
0-1 km storm-relative helicity: 88 m²/s²
0-3 km storm-relative helicity: 129 m²/s²
Significant tornado parameter: 0.2
Supercell composite: 2.7

Open this sounding in Storm Lab

The text

As transmitted.

059 
WGUS54 KOUN 310907
FFWOUN
OKC055-057-311400-
/O.NEW.KOUN.FF.W.0025.210531T0907Z-210531T1400Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Norman OK
407 AM CDT Mon May 31 2021

The National Weather Service in Norman has issued a

* Flash Flood Warning for...
  Central Greer County in southwestern Oklahoma...
  East Central Harmon County in southwestern Oklahoma...

* Until 900 AM CDT.

* At 407 AM CDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Between 2 and 4 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...
  Mangum, Willow and Brinkman.

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.

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

&&

LAT...LON 3479 9983 3497 9964 3510 9946 3504 9943
      3472 9945 3472 9948 3472 9956 3472 9960
      3472 9961 3472 9963 3472 9967 3471 9988

FLASH FLOOD...RADAR INDICATED

$$

11

2 follow-up statements

140 
WGUS74 KOUN 311037
FFSOUN

Flash Flood Statement
National Weather Service Norman OK
537 AM CDT Mon May 31 2021

OKC055-057-311400-
/O.CON.KOUN.FF.W.0025.000000T0000Z-210531T1400Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Greer OK-Harmon OK-
537 AM CDT Mon May 31 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 9 AM CDT THIS MORNING 
FOR CENTRAL GREER AND EAST CENTRAL HARMON COUNTIES...

At 537 AM CDT, Doppler radar indicated that the heavy rain has ended 
across Greer and Harmon counties. However, with areas of 2 to 4 
inches of rain earlier this morning, areas of flash flooding may 
continue through daybreak.

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...
  Mangum, Willow and Brinkman.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

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

&&

LAT...LON 3479 9983 3497 9964 3510 9946 3504 9943
      3472 9945 3472 9948 3472 9956 3472 9960
      3472 9961 3472 9963 3472 9967 3471 9988

FLASH FLOOD...RADAR INDICATED

$$

11

014 
WGUS74 KOUN 311240
FFSOUN

Flash Flood Statement
National Weather Service Norman OK
740 AM CDT Mon May 31 2021

OKC055-057-311400-
/O.CON.KOUN.FF.W.0025.000000T0000Z-210531T1400Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Greer OK-Harmon OK-
740 AM CDT Mon May 31 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 9 AM CDT THIS MORNING 
FOR CENTRAL GREER AND EAST CENTRAL HARMON COUNTIES...

At 740 AM CDT, Doppler radar indicated thunderstorms had produced 
heavy rain from north of Gould to west of Mangum to near Brinkman 
earlier this morning where an estimated 4 to locally 6 inches of 
rain has fallen. Although precipitation has ended across the warned 
area, flooding will remain likely as the water from this morning's 
heavy rainfall continues to flow downstream.

HAZARD...Flash flooding caused by thunderstorms.

SOURCE...Doppler radar.

IMPACT...Flooding of small creeks, streams and roads as well as
         other drainage and low lying areas.

Some locations that will experience flash flooding include...
  Mangum, Willow and Brinkman.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

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

&&

LAT...LON 3479 9983 3497 9964 3510 9946 3504 9943
      3472 9945 3472 9948 3472 9956 3472 9960
      3472 9961 3472 9963 3472 9967 3471 9988

FLASH FLOOD...RADAR INDICATED

$$

.speg.

The office that day

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

Issued	Product	Office	Counties	Lasted
May 30, 8:11 PM CDT	River Flood Warning	OUN	Major, Woods, Woodward	25 hr
May 30, 8:14 PM CDT	River Flood Advisory	OUN	Kingfisher, Logan	48 hr
May 30, 8:15 PM CDT	River Flood Advisory	OUN	Alfalfa, Woods	19 hr
May 31, 1:52 AM CDT	Special Weather Statement	OUN	Harmon	38 min
May 31, 2:59 AM CDT	Areal Flood Advisory	OUN	Beckham, Greer, Harmon, Jackson, Kiowa	6 hr
May 31, 6:46 AM CDT	Areal Flood Advisory	OUN	Comanche	3 hr
May 31, 11:26 AM CDT	River Flood Warning	OUN	Greer, Jackson	3 hr
May 31, 11:27 AM CDT	River Flood Advisory	OUN	Comanche, Cotton	27 hr
May 31, 11:30 AM CDT	River Flood Advisory	OUN	Cotton	51 hr
May 31, 2:46 PM CDT	River Flood Advisory	OUN	Greer, Jackson	19 min
May 31, 3:34 PM CDT	River Flood Warning	OUN	Pottawatomie, Seminole	10 hr
May 31, 3:35 PM CDT	River Flood Advisory	OUN	Blaine, Canadian	6 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.