Hail and Damaging Wind in Oklahoma, May 17, 2001

EASTERN OKLAHOMA/NORTHWEST ARKANSAS FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TULSA OK
320 PM CDT THU MAY 17 2001

ADDITIONAL STORMS NOW STARTING BE COME MORE LINEAR ALONG SFC BOUNDARY
THAT EXTENDS ROUGHLY FROM NE KS TO WC OK. RELATIVELY WEAK FLOW WILL
KEEP STORM MOVEMENT ON THE SLOWER SIDE...SO CURRENT ACTIVITY ACROSS
KS SHOULD ENTER THE NW CORNER OF CWA AROUND BY 21Z. STORMS WILL
CONTINUE TO SLOWLY PROPAGATE E-SE UNLESS NEW CONVECTION FORMS ON
OUTFLOW BOUNDARIES. WITH AFOREMENTIONED WEAK MID/UPPER FLOW
FLOW...SEVERE THREAT MAY DIMINISH SOMEWHAT WITH LOSS OF AFTERNOON
HEATING. HIGH PWS...DEVELOPING LOW LEVEL JET AND SLOW MOVEMENT OF
STORMS WILL PROMOTE A HEAVY RAIN THREAT FOR OVERNIGHT. WILL KEEP
MENTION OF HEAVY RAIN AT TIMES IN ZONES. EVENING SHIFT WILL WANT TO
MONITOR FLOOD POTENTIAL ESP. ACROSS NRN ZONES WHERE HIGHEST POPS
WILL BE TONIGHT. WILL FLIP-FLOP TOMORROW AND PUT HIGHEST POPS IN
SOUTH AND REDUCE TO HIGH CHANCE ACROSS THE NORTH. FRONT AND UPPER
DISTURBANCE TO MOVE AWAY FROM AREA BY LATE TOMORROW DAY...SO DONT
THINK RAIN WILL BE IN PICTURE(AT LEAST IN NE OK)ALL DAY. DRY
CONDITIONS EXPECTED AREAWIDE FRIDAY NIGHT INTO MOST OF
SATURDAY...BEFORE ANOTHER S/W APPROACHES LATE AFTERNOON SATURDAY
FROM THE WEST. SEVERAL WAVES LOOK TO AFFECT THE AREA THROUGH MONDAY
BEFORE UPPER TROUGH AXIS MOVES EAST...SO WILL KEEP RAIN CHANCES IN
TIL THEN.

00Z MRF AND TO A LESSER EXTENT 12Z AVN CLOSES OFF UPPER LOW AS IT
DROPS SE IN TO THE LOWER GREAT LAKES REGION. UPPER LOW MOVES VERY
SLOWLY EAST IN THE MID TO LATE NEXT WEEK TIME FRAME. LOOKS LIKE
BELOW NORMAL TEMPS IF THIS SCENARIO VERIFIES. WILL LEAVE EXTENDED
PARTLY CLOUDY AND DRY FOR NOW...BUT WILL LOWER TEMPS
TUES-THURS.

FCSTID = 23
TUL   65  75  58  81 /  70  50  10  20
FSM   66  79  61  83 /  50  70  20  10
MLC   67  79  60  80 /  50  70  20  10
BVO   63  74  56  80 /  80  50  10  20
FYV   63  74  55  78 /  60  50  20  10
BYV   63  74  55  78 /  60  50  20  10
MIO   63  73  55  78 /  70  50  40  10
MKO   65  74  57  79 /  70  50  10  20
F10   65  75  58  81 /  70  50  10  20
HHW   69  80  59  81 /  50  70  20  20

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

ARZ001-002-010-011-019-020-029-OKZ049-053>076-181100-

EASTERN OKLAHOMA/NORTHWEST ARKANSAS HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE TULSA OK
100 PM CDT THU MAY 17 2001

...A FEW SEVERE THUNDERSTORMS ARE EXPECTED THROUGH TONIGHT...

A COLD FRONT EXTENDED FROM NORTHEAST KANSAS INTO THE OKLAHOMA
PANHANDLE EARLY THIS AFTERNOON. SCATTERED THUNDERSTORMS ARE EXPECTED
TO DEVELOP ALONG THE FRONT AS IT CONTINUES MOVING SOUTHEAST INTO
NORTHERN OKLAHOMA THIS EVENING. THUNDERSTORMS WILL BECOME MORE
WIDESPREAD ALONG AND JUST AHEAD OF THE FRONT THIS EVENING AS AN
UPPER LEVEL SYSTEM APPROACHES FROM THE WEST. THE COLD FRONT AND
THUNDERSTORMS WILL SPREAD INTO NORTHEAST OKLAHOMA BY THIS EVENING
AND INTO SOUTHEAST OKLAHOMA AND NORTHWEST ARKANSAS LATER TONIGHT.

WIDELY SCATTERED THUNDERSTORMS COULD ALSO DEVELOP ACROSS NORTHEAST
OKLAHOMA THIS AFTERNOON AHEAD OF THE FRONT AS STRONG HEATING MAKES
THE ATMOSPHERE VERY UNSTABLE. ISOLATED SEVERE THUNDERSTORMS WILL BE
POSSIBLE AS EARLY AS 4 PM...BUT A BETTER CHANCE FOR STRONG
TO SEVERE THUNDERSTORMS WILL BE THIS EVENING AND OVERNIGHT ACROSS
PARTS OF EASTERN OKLAHOMA AND NORTHWEST ARKANSAS. HAIL LARGER THAN
GOLF BALLS AND DAMAGING WINDS CAN BE EXPECTED FROM SEVERE
THUNDERSTORMS TONIGHT.

.SPOTTER ACTIVATION...
SPOTTER ACTIVATION MAY BE NEEDED AS EARLY AS 4 PM IN NORTHEAST
OKLAHOMA AND AFTER 9 PM IN EAST CENTRAL OKLAHOMA AND NORTHWEST
ARKANSAS.

.DISCUSSION...
STRONG SURFACE HEATING MAY HELP PRODUCE A FEW THUNDERSTORMS IN
NORTHERN OKLAHOMA OR SOUTHERN KANSAS THIS AFTERNOON...BUT RELATIVELY
WEAK FORCING WILL LIMIT THE NUMBER OF STORMS. BY EARLY THIS
EVENING...SCATTERED THUNDERSTORMS ARE EXPECTED TO DEVELOP AND
ORGANIZE ALONG THE COLD FRONT IN KANSAS AND NORTHWEST OKLAHOMA AND
SPREAD SOUTHEAST. CAPE VALUES OVER 3000 J/KG IN AREAS JUST AHEAD OF
THE COLD FRONT INDICATE THAT SOME OF THE STORMS WILL BE SEVERE AS
THEY SPREAD INTO EASTERN OKLAHOMA THIS EVENING. THE EXTREMELY
UNSTABLE AIRMASS ACROSS THE AREA SUGGESTS THAT A FEW SUPERCELLS WILL
BE POSSIBLE DESPITE LIMITED WIND SHEAR. THE BEST CHANCE FOR
SUPERCELL THUNDERSTORMS WILL BE LATE THIS AFTERNOON OR EARLY THIS
EVENING WITH ANY STORMS THAT DEVELOP AHEAD OF THE COLD FRONT.

THE PRIMARY THREAT FOR SEVERE THUNDERSTORMS THROUGH TONIGHT WILL BE
IN AREAS NORTH OF A LINE FROM MCALESTER TO FORT SMITH. VERY LARGE
HAIL AND DAMAGING WIND GUSTS ARE EXPECTED WITH ANY SEVERE
THUNDERSTORMS THROUGH TONIGHT. THUNDERSTORMS ARE EXPECTED TO
GRADUALLY WEAKEN AFTER MIDNIGHT AS THEY MOVE INTO A SLIGHTLY MORE
STABLE AIRMASS.

THREAT TABLE
VALID THROUGH 1200 UTC FRIDAY
AREA 1...ALONG AND NORTH OF A MCALESTER TO FORT SMITH LINE
THUNDERSTORM PROBABILITY...100
SEVERE PROBABILITY IF STORMS OCCUR...95
SIGNIFICANT SEVERE PROBABILITY IF STORMS OCCUR...60

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.

.OTHER HAZARDS...
LOCALLY HEAVY RAINS WILL BE POSSIBLE TONIGHT AS SLOW MOVING
THUNDERSTORMS DEVELOP AND ORGANIZE ACROSS THE AREA.

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