Hail and Damaging Winds in Oklahoma, August 15, 2001

EASTERN OKLAHOMA/NORTHWEST ARKANSAS FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TULSA OK
245 PM CDT WED AUG 15 2001

COLD FRONT CONTINUES TO MOVE SOUTHEAST THIS AFTERNOON INTO
NORTH-CENTRAL OKLAHOMA.  ENHANCED CU HAS DEVELOPED AHEAD OF BOUNDARY
WITH A FEW RADAR ECHOES STARTING TO SHOW UP SW OF PNC FROM KINX. SFC
MOISTURE CONVERGENCE HAS BEEN ONGOING IN THIS AREA...AND EXPECT SCT
TSTMS TO DEVELOP IN THE NEXT COUPLE OF HOURS...PUSHING EASTWARD INTO
NE OK ZONES BY LATE AFTERNOON.  ATMOSPHERE HAS BECOME MODERATELY
UNSTABLE ACROSS THIS AREA WITH LIS RANGING FROM -5 TO -7 DEG C.
ISOLATED SVR STORMS WILL BE POSSIBLE...MAINLY THROUGH THE EVENING
HOURS AS STORMS PUSH EAST ALONG FRONT.

THUNDERSTORMS MAY BECOME MORE WIDESPREAD ALONG FRONT AFTER MIDNIGHT
AS LOW LEVEL MOISTURE/JET INCREASES OVER SE OK/NW ARK. THIS AREA
WILL ALSO BE IN RIGHT REAR QUAD OF 70KT 300 MB JET.  COULD SEE A FEW
LINGERING TSTMS OVER FAR SE OK TOWARD THE RED RIVER THU MORNING...
HOWEVER PRECIP SHOULD PUSH SOUTH BY EARLY AFTERNOON AS COLD FRONT
MOVES INTO NE TX/SOUTHERN ARK.  EXPECT SOME CLEARING BEHIND FRONT
OVER NORTHERN ZONES AND WITH LITTLE CAA FORECAST BEHIND FRONT...
TEMPS SHOULD BE BACK INTO THE LOW TO MID 90S WITH THE LIMITED CLOUD
COVER.

WEAK 50H SHORTWAVE PROGGED TO MOVE INTO AREA ON FRI UNDER NW FLOW.
MAY JUST GIVE FA MID/HIGH LEVEL CLOUDS ON FRI AND WILL GO WITH DRY
FORECAST FOR NOW. STRONGER SHORTWAVE TROUGH DIGS INTO KANSAS/OK FRI
NIGHT WITH THE POTENTIAL FOR MCS DEVELOPMENT OVER KANSAS...MOVING
SE INTO NE OK/NW ARK LATE FRIDAY NIGHT INTO SATURDAY.  WILL BUMP
POPS TO CHANCE CATEGORY (30%) ON SAT.  NO OTHER SIG CHANGES TO
EXTENDED.  WILL LIKELY TWEAK 1ST PERIOD POPS AT ISSUANCE TIME...
DEPENDING ON LATEST RADAR TRENDS.

FCSTID = 12

PRELIM NUMBERS BELOW
TUL   68  95  66  95 /  50   0  10  10
FSM   70  92  65  94 /  60  30   0   0
MLC   70  93  67  96 /  50  20   0   0
BVO   66  95  64  94 /  50   0  10  10
FYV   64  85  59  90 /  60  20   0  10
BYV   64  85  59  90 /  60  20   0  10
MIO   66  92  63  92 /  60  10  10  10
MKO   68  94  65  95 /  50  10   0  10
F10   68  95  66  95 /  50   0  10  10
HHW   72  91  69  95 /  60  50   0   0

.TSA...
AR...NONE.
OK...NONE.

ARZ001-002-010-011-019-020-029-OKZ049-053>076-161100-

EASTERN OKLAHOMA/NORTHWEST ARKANSAS HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE TULSA OK
209 PM CDT WED AUG 15 2001

...ISOLATED SEVERE THUNDERSTORMS EXPECTED LATE THIS AFTERNOON AND
TONIGHT ACROSS EASTERN OKLAHOMA AND NORTHWEST ARKANSAS...

A COLD FRONT...WHICH WAS MOVING INTO SOUTHEAST KANSAS AND NORTHWEST
OKLAHOMA THIS AFTERNOON...IS EXPECTED TO MOVE INTO NORTHEAST
OKLAHOMA BY EARLY EVENING AND ACROSS THE AREA OVERNIGHT.  SCATTERED
THUNDERSTORMS ARE EXPECTED TO DEVELOP NEAR THE FRONT IN CENTRAL
OKLAHOMA WITH OTHER STORMS POSSIBLY DEVELOPING IN SOUTHEAST KANSAS
AND SOUTHERN MISSOURI. ISOLATED SEVERE STORMS MAY MOVE EASTWARD INTO
EASTERN OKLAHOMA AFTER 5PM WITH MORE WIDESPREAD DEVELOPMENT POSSIBLE
DURING THE EVENING. THE STORMS MAY DEVELOP INTO A LINE ALONG THE
FRONT AS IT PUSHES INTO NORTHWEST ARKANSAS AND SOUTHEAST OKLAHOMA
TOWARDS MIDNIGHT...WITH THE STORMS EXPECTED TO MOVE SOUTH OF THE
AREA BY THURSDAY MORNING.

DAMAGING WINDS WILL BE THE MAIN THREAT FROM THE STORMS WITH THE
THREAT HIGHEST IN NORTHEAST OKLAHOMA BETWEEN 5PM AND 9PM AND IN
SOUTHEAST OKLAHOMA AND NORTHWEST ARKANSAS AFTER 8PM.

.SPOTTER ACTIVATION...
SPOTTERS ACTIVATION MAY BE REQUIRED IN EASTERN OKLAHOMA AND
NORTHWEST ARKANSAS LATE THIS AFTERNOON AND TONIGHT.

.DISCUSSION...
LOW LEVEL MOISTURE WAS MOVING NORTHEASTWARD OUT OF WEST TEXAS AND
THE ADDITION OF THE MOISTURE TO THE AIRMASS AHEAD OF THE ONCOMING
FRONT WILL CREATE CAPES FROM 1500 TO 2000 J/KG IN EASTERN OKLAHOMA
BY LATE AFTERNOON. INSTABILITY AND LIFT NEAR THE FRONT WILL BE
GREATER OVER CENTRAL OKLAHOMA AND SOUTHEAST KANSAS THIS AFTERNOON...
WHERE INITIAL DEVELOPMENT IS EXPECTED. IF ANY STORMS DEVELOP OR
ENTER EASTERN OKLAHOMA LATE THIS AFTERNOON...DOWNBURST WINDS WILL BE
THE MAIN THREAT WITH HAIL TO 1 INCH ALSO POSSIBLE. FACTORS THAT MAY
LIMIT THE SEVERE THREAT ARE VEERING SURFACE WINDS AHEAD OF THE FRONT
AND THE LATE ARRIVAL OF LOW LEVEL MOISTURE. BY EVENING...THE
APPROACH OF THE UPPER LEVEL TROUGH AND INCREASING LOW LEVEL JET
WINDS WILL INCREASE THE CHANCE OF THE CONVECTION BECOMING ORGANIZED
ALONG THE FRONT. ELEVATED LIFTED INDICES ARE FORECAST TO REMAIN IN
THE -2 TO -4 RANGE OVERNIGHT WHICH MAY KEEP THE THREAT FOR SEVERE
STORMS GOING UNTIL AFTER MIDNIGHT IN NORTHWEST ARKANSAS AND
SOUTHEAST OKLAHOMA.

THREAT TABLE
VALID THROUGH 1200 UTC THURSDAY
AREA 1...EASTERN OKLAHOMA AND NORTHWEST ARKANSAS
THUNDERSTORM PROBABILITY...100
SEVERE PROBABILITY IF STORMS OCCUR...40
SIGNIFICANT SEVERE PROBABILITY IF STORMS OCCUR...10

THREAT AREAS DEFINE THE GREATEST RISK. PROBABILITIES ARE IN PERCENT.
SIGNIFICANT SEVERE IS DEFINED AS F1 OR GREATER WIND/TORNADO DAMAGE
AND/OR GOLF BALL SIZE HAIL OR LARGER.

RELATED GRAPHICAL INFORMATION CAN BE FOUND AT: WWW.SRH.NOAA.GOV/TULSA