Tornado and Hail in Oklahoma, October 17, 2007

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TULSA OK
151 AM CDT WED OCT 17 2007

.DISCUSSION...

...SIGNIFICANT SEVERE WEATHER EVENT EXPECTED LATE THIS AFTERNOON AND
   EVENING WITH THE POTENTIAL FOR STRONG/LONG LIVED TORNADOES...

ELEVATED SHOWERS/THUNDERSTORMS STARTING TO DEVELOP OVER PORTIONS
OF NORTHEAST OKLAHOMA EARLY THIS MORNING IN LOW LEVEL JET. EXPECT
THIS ACTIVITY TO INCREASE IN COVERAGE/INTENSITY THROUGH THE
MORNING HOURS BEFORE LIFTING NORTH OF THE AREA BY EARLY AFTERNOON.
A FEW OF THESE STORMS COULD BECOME SEVERE WITH MARGINALLY SEVERE
HAIL.

MAIN FOCUS SHIFTS TO THIS AFTERNOON AS STRONG UPPER LEVEL SHORT
WAVE LIFTS RAPIDLY NORTHEAST INTO OKLAHOMA AND BECOMES NEGATIVELY
TILTED WITH 90 KT-250 MB SPEED MAX. DRY LINE EXPECTED TO BE NEAR
THE INTERSTATE 35 CORRIDOR BY 00Z WITH SUPERCELL THUNDERSTORMS
RAPIDLY DEVELOPING ALONG BOUNDARY BY THIS TIME.

ALTHOUGH ONLY MODEST SURFACE HEATING IS EXPECTED TODAY DUE TO MORNING
CONVECTION/EXTENSIVE CLOUD COVER...STEEP MID LEVEL LAPSE RATES ARE
EXPECTED TO SPREAD OVER THE WARM SECTOR THIS AFTERNOON ALLOWING
ATMOSPHERE TO BECOME MODERATELY UNSTABLE WITH MLCAPES AROUND 1000 J/KG.
WIND PROFILES AHEAD OF DRY LINE ARE FORECAST TO BECOME VERY STRONG
BY LATE AFTERNOON WITH 60-70 KT DEEP LAYER SHEAR. LARGE LOOPING
HODOGRAPHS COMBINED WITH LOW LCL HEIGHTS/SMALL TEMP/DEW- POINT
SPREADS INDICATE THE POTENTIAL FOR A FEW STRONG/LONG LIVED
TORNADOES ACROSS EASTERN OKLAHOMA/NORTHWEST ARKANSAS LATE THIS
AFTERNOON THROUGH THE EVENING HOURS. IN ADDITION...VERY LARGE HAIL
WILL ALSO BE LIKELY GIVEN MID LEVEL LAPSE RATES/LOW WET BULB ZERO
HEIGHTS...ESPECIALLY ACROSS NORTHEAST OKLAHOMA. THE SEVERE WEATHER
THREAT WILL LIKELY END AROUND MIDNIGHT AS STORMS SHIFT NORTHEAST
OF FA.

REMAINDER OF FORECAST/EXTENDED STAYED CLOSE TO THE MEX GUIDANCE.
ANOTHER STRONG UPPER LEVEL TROUGH IS EXPECTED TO MOVE INTO THE
CENTRAL PLAINS ON SUNDAY WITH COLD FRONT PUSHING THROUGH AREA
DURING THIS TIME. THE POTENTIAL FOR A STRONG TO SEVERE SQUALL LINE
APPEARS POSSIBLE WITH FROPA GIVEN INSTABILITY/DYNAMICS WITH
SYSTEM. TIMING HOWEVER WILL REMAIN UNCERTAIN AS GFS CONTINUES TO
DEVIATE FROM RUN TO RUN.

&&

.PRELIMINARY POINT TEMPS/POPS...
TUL   75  60  77  52 /  90  60  20  10
FSM   75  61  84  52 /  70  80   0  10
MLC   77  59  84  50 /  80  50   0  10
BVO   73  56  74  50 /  90  60  20  10
FYV   75  61  77  48 /  80  80   0  10
BYV   74  60  78  49 /  80  90   0  10
MKO   75  57  78  51 /  90  60  10  10
MIO   75  59  75  50 /  90  80  20  10
F10   76  58  78  51 /  80  50  10  10
HHW   79  62  85  54 /  60  40   0  10

&&

.TSA WATCHES/WARNINGS/ADVISORIES...
OK...NONE.
AR...NONE.
&&

SHORT TERM...18
LONG TERM....12

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE TULSA OK
500 AM CDT WED OCT 17 2007

ARZ001-002-010-011-019-020-029-OKZ049-053>076-181000-
ADAIR OK-BENTON AR-CARROLL AR-CHEROKEE OK-CHOCTAW OK-CRAIG OK-
CRAWFORD AR-CREEK OK-DELAWARE OK-FRANKLIN AR-HASKELL OK-LATIMER OK-
LE FLORE OK-MADISON AR-MAYES OK-MCINTOSH OK-MUSKOGEE OK-NOWATA OK-
OKFUSKEE OK-OKMULGEE OK-OSAGE OK-OTTAWA OK-PAWNEE OK-PITTSBURG OK-
PUSHMATAHA OK-ROGERS OK-SEBASTIAN AR-SEQUOYAH OK-TULSA OK-WAGONER OK-
WASHINGTON OK-WASHINGTON AR-
500 AM CDT WED OCT 17 2007

...SEVERE WEATHER OUTBREAK EXPECTED BY LATE AFTERNOON AND EVENING
WITH THE POSSIBILITY OF STRONG TORNADOES...LARGE HAIL AND DAMAGING
WINDS...

THIS OUTLOOK IS FOR NORTHWEST AND WEST CENTRAL ARKANSAS AS WELL AS
MUCH OF EASTERN OKLAHOMA.

.DAY ONE...TODAY AND TONIGHT.
TORNADO.
	RISK...ELEVATED.
	AREA...EASTERN OKLAHOMA AND NORTHWEST ARKANSAS.
	ONSET...AFTER 4 PM.

SEVERE THUNDERSTORM.
	RISK...SIGNIFICANT.
        AREA...EASTERN OKLAHOMA AND NORTHWEST ARKANSAS.
        ONSET...AFTER 7 AM AND AGAIN AFTER 4 PM.

DISCUSSION...
A 40 TO 50 KNOT LOW-LEVEL JET COMBINED WITH STEEPENING LAPSE RATES HAS
RESULTED IN SCATTERED CONVECTION ACROSS THE AREA OVERNIGHT.
ADDITIONAL THUNDERSTORMS OVER WESTERN AND NORTHWESTERN OKLAHOMA
COULD AFFECT PARTS OF NORTHEAST OKLAHOMA EARLY THIS MORNING. A FEW
OF THE STRONGER STORMS MAY PRODUCE MARGINALLY SEVERE HAIL.

ATTENTION WILL TURN TO THE DRYLINE THAT WILL MIX INTO WESTERN TO
CENTRAL OKLAHOMA BY LATE AFTERNOON. HEATING WILL BE TEMPERED SOME BY
THE CLOUD COVER...ALTHOUGH LATE AFTERNOON SURFACE BASED CAPE VALUES
SHOULD STILL INCREASE TO AROUND 1000 J/KG. AS A 90 KNOT MID-LEVEL
JET AND HEIGHT FALLS PUNCH EAST INTO THE TEXAS PANHANDLE...SCATTERED
THUNDERSTORM DEVELOPMENT IS EXPECTED ALONG THE DRYLINE BY MID TO
LATE AFTERNOON. GIVEN THE VERY STRONG DEEP-LAYERED SHEAR...ANY
THUNDERSTORM THAT DEVELOPS WILL ROTATE AND QUICKLY BECOME SEVERE.

DISCRETE SUPERCELLS MAY BEGIN TO AFFECT PORTIONS OF EASTERN
OKLAHOMA BY LATE AFTERNOON...WITH THE POSSIBILITY OF A FEW
LONG-LIVED STRONG TORNADOES AND VERY LARGE HAIL. SEVERE THUNDERSTORMS
WILL QUICKLY SPREAD THROUGH THE REMAINDER OF EASTERN OKLAHOMA AND
NORTHWEST ARKANSAS...WITH THE THREAT ENDING ACROSS THE AREA AFTER
ABOUT 2 AM.

SPOTTER AND EMERGENCY MANAGEMENT ACTION STATEMENT...
SPOTTER GROUPS AND EMERGENCY MANAGEMENT AGENCIES SHOULD PREPARE FOR
ACTIVATION THIS AFTERNOON.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY.
THURSDAY...NO HAZARDS.
FRIDAY...NO HAZARDS.
SATURDAY...NO HAZARDS.
SUNDAY...THUNDERSTORM POTENTIAL.
MONDAY...THUNDERSTORM POTENTIAL.
TUESDAY...NO HAZARDS.

EXTENDED DISCUSSION...
THE MAIN UPPER SYSTEM WILL CLEAR THE AREA BY THURSDAY...WITH
PLEASANT WEATHER EXPECTED FOR MOST OF THE WEEKEND. THE NEXT UPPER
SYSTEM SHOULD MOVE INTO THE CENTRAL AND SOUTHERN PLAINS SUNDAY
NIGHT...BRINGING A CHANCE OF SHOWERS AND THUNDERSTORMS THROUGH
MONDAY.

WWW.SRH.NOAA.GOV/TULSA CONTAINS ADDITIONAL TABULAR AND GRAPHICAL
INFORMATION.