Alert archive / Oklahoma / Flash Flood Warnings in 2009

Flash Flood Warning 28, NWS Norman, OK

September 21, 2009Bryan County, Oklahoma

NWS Norman, OK issued this flash flood warning at Sep 21, 2009, 10:10 PM CDT for Bryan County, 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 counties it named.

The facts

Issued: Sep 21, 2009, 10:10 PM CDT (03:10 UTC)
Expired: Sep 22, 2009, 1:15 AM CDT
In force: 3 hr
Issued by: NWS Norman, OK
Area: Storm-based polygon
Flood severity: None

County Bryan County, OK

The radar

The Norman radar (KTLX), 179 km from the middle of the area, began a volume at 03:12 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, 3.2 hours before the alert went out and 158 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: 2664 J/kg
Mixed-layer CIN: -12 J/kg
Mixed-layer LCL: 1499 m above ground
0-6 km bulk shear: 28 kt
0-1 km storm-relative helicity: 102 m²/s²
0-3 km storm-relative helicity: 190 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

What forecasters said that day

The local office's own words before this flash flood warning went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Norman, OK wrote its last area forecast discussion before this flash flood warning went out at Sep 21, 6:30 PM CDT, 3 hours 40 minutes earlier.

Area forecast discussion, Sep 21, 6:30 PM CDT, 3 hours 40 minutes before

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Hazardous weather outlook, Sep 21, 5:00 PM CDT, 5 hours 10 minutes before

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE NORMAN OK
500 PM CDT MON SEP 21 2009

OKZ004>048-050>052-TXZ083>090-221000-
HARPER-WOODS-ALFALFA-GRANT-KAY-ELLIS-WOODWARD-MAJOR-GARFIELD-NOBLE-
ROGER MILLS-DEWEY-CUSTER-BLAINE-KINGFISHER-LOGAN-PAYNE-BECKHAM-
WASHITA-CADDO-CANADIAN-OKLAHOMA-LINCOLN-GRADY-MCCLAIN-CLEVELAND-
POTTAWATOMIE-SEMINOLE-HUGHES-HARMON-GREER-KIOWA-JACKSON-TILLMAN-
COMANCHE-STEPHENS-GARVIN-MURRAY-PONTOTOC-COAL-COTTON-JEFFERSON-
CARTER-JOHNSTON-ATOKA-LOVE-MARSHALL-BRYAN-HARDEMAN-FOARD-WILBARGER-
WICHITA-KNOX-BAYLOR-ARCHER-CLAY-
500 PM CDT MON SEP 21 2009

THIS HAZARDOUS WEATHER OUTLOOK COVERS NORTHERN...WESTERN...
CENTRAL...AND SOUTHERN OKLAHOMA...AND WESTERN NORTH TEXAS.

.DAY ONE...THIS AFTERNOON AND TONIGHT...

THUNDERSTORM OUTLOOK...
THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THROUGH TONIGHT
ACROSS PORTIONS OF OKLAHOMA AND WESTERN NORTH TEXAS.

LOCATION...
THE SLIGHT RISK AREA COVERS LOCATIONS SOUTH AND EAST OF A LINE
EXTENDING FROM CHANDLER TO NORMAN TO DUNCAN AND WICHITA
FALLS.

TIMING...
THE MOST LIKELY TIME FOR SEVERE THUNDERSTORMS WILL BE LATE
THIS AFTERNOON INTO THE MID TO LATE EVENING HOURS.

IMPACTS...
SOME DAMAGE TO AUTOMOBILES AND TENDER VEGETATION FROM LARGE HAIL TO
THE SIZE OF GOLFBALLS.

DAMAGING WIND GUSTS TO 65 MPH.

ISOLATED TORNADOES.

RECOMMENDED ACTIONS...
STORM SPOTTER GROUPS AND EMERGENCY MANAGEMENT PERSONNEL ACROSS THE
RISK AREA SHOULD PLAN FOR SEVERE WEATHER OPERATIONS FROM THIS
AFTERNOON INTO EARLY TUESDAY MORNING.

DISCUSSION...
AN UPPER-LEVEL STORM SYSTEM MOVING SOUTH THROUGH THE CENTRAL ROCKIES
AND HIGH PLAINS WILL PUSH A COLD FRONT ACROSS SOUTHERN
AND EASTERN OKLAHOMA AND NORTH TEXAS THIS EVENING.  INCREASING
INSTABILITY AHEAD OF THE FRONT... COMBINED WITH MODEST VALUES OF
DEEP-LAYER WIND SHEAR... WILL LEAD TO THE DEVELOPMENT OF STRONG TO
SEVERE THUNDERSTORMS... ESPECIALLY NEAR THE COLD FRONT.

THE PRIMARY SEVERE WEATHER THREATS ARE EXPECTED TO BE STRONG WINDS
AND LARGE HAIL. HOWEVER... IF A SURFACE LOW PRESSURE CENTER FORMS
ALONG THE COLD FRONT... IT COULD LOCALLY INCREASE THE SURFACE WIND
SPEEDS. THESE STRONGER WINDS... COMBINED WITH THE DEVELOPMENT OF A
LOW-LEVEL JET... MAY RESULT IN A SMALL TORNADO THREAT THIS EVENING.

PROBABILITY TABLE...
VALID THROUGH 700 AM CDT TUESDAY SEP 22.
PROBABILITY OF THUNDERSTORMS OCCURRING IN THE
              NWS NORMAN COUNTY WARNING AREA...100 PERCENT.
PROBABILITY OF SEVERE STORMS IF STORMS OCCUR...100 PERCENT.

OTHER HAZARDOUS WEATHER...
THUNDERSTORMS LATE THIS EVENING AND OVERNIGHT MAY ALSO PRODUCE
HEAVY RAIN... LEADING TO LOCALIZED FLOODING PROBLEMS. THIS IS
EXPECTED TO BE MOST PRONOUNCED OVER THE SOUTHEAST PART OF OKLAHOMA.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY...

THUNDERSTORM OUTLOOK...
THUNDERSTORM ACTIVITY MAY LINGER INTO TUESDAY. THE STORM SYSTEM
RESPONSIBLE FOR THE COLD FRONT IS EXPECTED TO REMAIN NEARLY
STATIONARY OVER THE PLAINS FOR THE REMAINDER OF THE WEEK... WITH A
CHANCE OF THUNDERSTORMS POSSIBLY ORGANIZING THURSDAY AND FRIDAY AS
THE UPPER STORM SYSTEM BEGINS TO MOVE EAST THROUGH THE CENTRAL
PLAINS.

OTHER HAZARDOUS WEATHER...
NONE.

THE NEXT SCHEDULED HAZARDOUS WEATHER OUTLOOK WILL BE ISSUED AT 5 AM
TUESDAY.

CJS/SIX

In the hours before

Local storm report, Sep 21, 5:38 PM CDT, 4 hours 32 minutes before

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Special weather statement, Sep 21, 5:41 PM CDT, 4 hours 29 minutes before

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Special weather statement, Sep 21, 5:56 PM CDT, 4 hours 14 minutes before

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Special weather statement, Sep 21, 6:05 PM CDT, 4 hours 5 minutes before

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Special weather statement, Sep 21, 6:20 PM CDT, 3 hours 50 minutes before

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Special weather statement, Sep 21, 6:43 PM CDT, 3 hours 27 minutes before

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The office that day

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

Issued	Product	Office	Counties	Lasted
Sep 21, 7:00 PM CDT	Flash Flood Warning	OUN	Hughes, Seminole	3 hr
Sep 21, 7:12 PM CDT	Severe Thunderstorm Warning	OUN	Murray	33 min
Sep 21, 7:15 PM CDT	Severe Thunderstorm Warning	OUN	Coal, Hughes, Pontotoc	60 min
Sep 21, 7:23 PM CDT	Severe Thunderstorm Warning	OUN	Carter, Johnston, Love, Marshall	67 min
Sep 21, 7:28 PM CDT	Severe Thunderstorm Warning	OUN	Coal, Pontotoc	47 min
Sep 21, 7:46 PM CDT	Severe Thunderstorm Warning	OUN	Murray	59 min
Sep 21, 7:57 PM CDT	Severe Thunderstorm Warning	OUN	Atoka, Bryan	78 min
Sep 21, 8:15 PM CDT	Severe Thunderstorm Warning	OUN	Coal	45 min
Sep 21, 8:32 PM CDT	Areal Flood Advisory	OUN	Carter, Johnston, Murray	3 hr
Sep 21, 9:48 PM CDT	Areal Flood Advisory	OUN	Bryan	117 min

Nearby

Flash Flood Warnings in Oklahoma, 2009 Every flash flood warning in 2009

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.