Alert archive / Oklahoma / Severe Thunderstorm Warnings in 2009

Severe Thunderstorm Warning 321, NWS Norman, OK

May 8, 2009Bryan County, Johnston County, Marshall County, Oklahoma

NWS Norman, OK issued this severe thunderstorm warning at May 8, 2009, 11:07 PM CDT for Bryan County, Johnston County, Marshall County, Oklahoma. It was in force for 38 min. No storm report in the archive falls inside the area while it was in force.

The area

The counties it named.

The facts

Issued
May 8, 2009, 11:07 PM CDT (04:07 UTC)
Expired
May 8, 2009, 11:45 PM CDT
In force
38 min
Issued by
NWS Norman, OK
Area
Storm-based polygon

Counties Bryan County, OK, Johnston County, OK, Marshall County, OK

The radar

The Norman radar (KTLX), 152 km from the middle of the area, began a volume at 04:08 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 watch it was issued in

The SPC watch in force over the same counties when this warning went out.

IssuedProductOfficeLasted
May 8, 5:52 PM CDTTornado WatchSPC11 hr

The nearest sounding before it

Norman, OK (KOUN), launched 00:00Z, 4.1 hours before the alert went out and 146 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, Norman, OK at 00:00Z on 2009-05-09Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 2143 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Norman, OK at 00:00Z on 2009-05-09The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 85 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
2143 J/kg
Mixed-layer CIN
-64 J/kg
Mixed-layer LCL
791 m above ground
0-6 km bulk shear
47 kt
0-1 km storm-relative helicity
85 m²/s²
0-3 km storm-relative helicity
208 m²/s²
Significant tornado parameter
1.2
Supercell composite
7.3

Open this sounding in Storm Lab

What forecasters said that day

The local office's own words before this severe thunderstorm 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 severe thunderstorm warning went out at May 8, 10:15 PM CDT, 52 minutes earlier.

Area forecast discussion, May 8, 10:15 PM CDT, 52 minutes before
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Hazardous weather outlook, May 8, 11:54 AM CDT, 11 hours 13 minutes before
HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE NORMAN OK
1154 AM CDT FRI MAY 8 2009

OKZ004>048-050>052-TXZ083>090-091000-
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-
1154 AM CDT FRI MAY 8 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 IS SOUTHEAST OF A LINE FROM SEYMOUR AND VERNON
TEXAS... TO DUNCAN AND PAULS VALLEY... TO SEMINOLE OKLAHOMA.

TIMING...
THE MOST LIKELY TIME FOR SEVERE THUNDERSTORMS WILL BE AFTER 4 PM
THROUGH THIS EVENING... AND POSSIBLY OVERNIGHT.

IMPACTS...
HAIL TO THE SIZE OF BASEBALLS CAUSING DAMAGE TO AUTOMOBILES...
VEGETATION... AND ROOFS AND WIND GUSTS TO 65 MPH.

RECOMMENDED ACTIONS...
STORM SPOTTER GROUPS AND EMERGENCY MANAGEMENT PERSONNEL ACROSS THE
RISK AREA SHOULD EXPECT SEVERE OPERATIONS FROM LATE THIS AFTERNOON
THROUGH AT LEAST THIS EVENING.

DISCUSSION...
A COLD FRONT WILL CONTINUE TO MOVE ACROSS OKLAHOMA AND NORTH TEXAS
THIS AFTERNOON... WITH A WARM AND HUMID AIRMASS IN PLACE AHEAD OF
THE FRONT. STRONG INSTABILITY WILL DEVELOP AHEAD OF THE FRONT THIS
AFTERNOON ACROSS PORTIONS OF SOUTHERN OKLAHOMA. CONVERGENCE ALONG
THE FRONT MAY BE SUFFICIENT TO OVERCOME THE CAP LEADING TO
THUNDERSTORM DEVELOPMENT. THE MAIN CONCERNS WILL BE VERY LARGE
HAIL... STRONG WINDS... AND HEAVY RAIN.

PROBABILITY TABLE...
VALID THROUGH 700 AM CDT SATURDAY MAY 9.
PROBABILITY OF THUNDERSTORMS OCCURRING IN THE
              NWS NORMAN COUNTY WARNING AREA...60 PERCENT.
PROBABILITY OF SEVERE STORMS IF STORMS OCCUR...90 PERCENT.

OTHER HAZARDOUS WEATHER...
HEAVY RAINFALL HAS LEFT THE GROUND SATURATED ACROSS PARTS OF THE
AREA. ANY ADDITIONAL HEAVY RAINFALL COULD RESULT IN RAPID RUNOFF AND
POSSIBLE FLASH FLOODING.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY...

THUNDERSTORM OUTLOOK...
THERE IS A SLIGHT RISK OF SEVERE STORMS ACROSS SOUTHEAST AND
SOUTH-CENTRAL OKLAHOMA AGAIN ON SATURDAY AND SUNDAY.  THERE WILL BE
A SLIGHT CHANCE OF THUNDERSTORMS EACH DAY FROM MONDAY THROUGH
THURSDAY.

OTHER HAZARDOUS WEATHER...
NONE.

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

MAXWELL

In the hours before

Local storm report, May 8, 10:03 PM CDT, 1 hour 4 minutes before
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Special weather statement, May 8, 10:26 PM CDT, 41 minutes before
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Special weather statement, May 8, 10:37 PM CDT, 30 minutes before
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Local storm report, May 8, 10:49 PM CDT, 18 minutes before
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Special weather statement, May 8, 10:58 PM CDT, 9 minutes before
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Special weather statement, May 8, 11:02 PM CDT, 5 minutes before
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The office that day

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

IssuedProductOfficeCountiesLasted
May 8, 7:26 PM CDTSevere Thunderstorm WarningOUNJefferson49 min
May 8, 7:28 PM CDTSevere Thunderstorm WarningOUNCarter, Garvin, Murray47 min
May 8, 7:50 PM CDTSevere Thunderstorm WarningOUNCarter55 min
May 8, 7:56 PM CDTAreal Flood AdvisoryOUNMurray2 hr
May 8, 8:01 PM CDTSevere Thunderstorm WarningOUNCarter, Jefferson, Stephens59 min
May 8, 8:42 PM CDTSevere Thunderstorm WarningOUNCarter, Love48 min
May 8, 8:44 PM CDTFlash Flood WarningOUNCarter3 hr
May 8, 8:58 PM CDTSevere Thunderstorm WarningOUNJohnston, Love, Marshall62 min
May 8, 9:07 PM CDTSevere Thunderstorm WarningOUNJefferson38 min
May 8, 9:26 PM CDTSevere Thunderstorm WarningOUNCarter, Love64 min
May 8, 9:37 PM CDTSevere Thunderstorm WarningOUNJefferson38 min
May 8, 9:39 PM CDTSevere Thunderstorm WarningOUNCarter, Murray33 min
May 8, 10:01 PM CDTSevere Thunderstorm WarningOUNMarshall44 min
May 8, 11:20 PM CDTSevere Thunderstorm WarningOUNCarter, Garvin, Stephens40 min
May 8, 11:27 PM CDTSevere Thunderstorm WarningOUNLove48 min
May 8, 11:42 PM CDTSevere Thunderstorm WarningOUNLove48 min
May 9, 12:00 AM CDTSevere Thunderstorm WarningOUNCleveland, McClain31 min
May 9, 12:15 AM CDTSevere Thunderstorm WarningOUNLove, Marshall45 min
May 9, 12:44 AM CDTSevere Thunderstorm WarningOUNMcClain, Pontotoc, Pottawatomie, Seminole46 min

Nearby

Severe Thunderstorm Warnings in Oklahoma, 2009Every severe thunderstorm 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.