Severe Thunderstorm Warning 77, NWS Tulsa, OK

EASTERN OKLAHOMA/NORTHWEST ARKANSAS FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TULSA OK
1013 AM CDT TUE APR 30 2002

ELEVATED CONVECTION THAT STARTED ACROSS NORTHWEST ARKANSAS THIS
MORNING HAS EXPANDED INTO A SMALL MCS WHICH WAS NOW LOCATED ACROSS
SOUTHERN MISSOURI AND NORTHEASTERN ARKANSAS. THIS ACTIVITY WILL
REMAIN EAST OF THE AREA THIS AFTERNOON.

WIDELY SCATTERED SHOWERS AND THUNDERSTORMS WERE DEVELOPING ACROSS
SOUTHEAST OKLAHOMA AND WEST CENTRAL ARKANSAS AT THIS TIME...IN
TERRAIN-FAVORED AREAS NORTH OF THE ADVANCING WARM FRONT. WILL HAVE
TO WATCH THIS ACTIVITY THROUGH THIS AFTERNOON AS AIRMASS
DESTABILIZES ALONG AND NORTH OF WARM FRONT.

WILL SEND AN UPDATED ZONE AND RDF PACKAGE BY 1030 AM TO MAKE SOME
MINOR FIRST PERIOD ADJUSTMENTS TO ZONES. WILL LOWER SOME OF THE MAX
TEMPERATURE FORECASTS ABOUT A CATEGORY AS CLOUD COVER LIKELY TO KEEP
TEMPERATURES BELOW THEIR FULL POTENTIAL IN MANY AREAS. WILL ALSO
ADJUST POPS TO REFLECT CURRENT AND EXPECTED TRENDS. WILL KEEP
HIGHEST POPS IN EASTERN AND NORTHERN ZONES WHERE CAPPING IS WEAKEST
AND WHERE FORCING FROM WARM FRONT IS MAXIMIZED.

NO CHANGES TO LATER PERIODS OF FORECAST.

FCSTID = 9

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

ARZ001-002-010-011-019-020-029-OKZ049-053>076-011200-

EASTERN OKLAHOMA / NORTHWEST ARKANSAS HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE TULSA OK
600 AM CDT TUE APR 30 2002

...A CHANCE OF SEVERE THUNDERSTORMS ACROSS NORTHEAST OKLAHOMA
AND NORTHWEST ARKANSAS THIS MORNING AND THEN AGAIN LATE THIS
AFTERNOON...

SCATTERED SHOWERS AND THUNDERSTORMS ARE POSSIBLE ACROSS NORTHEAST
OKLAHOMA EARLY THIS MORNING NORTH OF A WARM FRONT THAT WAS LOCATED
ALONG THE RED RIVER. THE THUNDERSTORMS WILL THEN SPREAD EAST INTO
NORTHWEST ARKANSAS BY MID-MORNING. ANY STORMS THAT DO DEVELOP WILL
BE CAPABLE OF BECOMING SEVERE WITH LARGE HAIL THE MAIN THREAT.

ADDITIONAL THUNDERSTORMS WILL BE POSSIBLE LATE THIS AFTERNOON AS THE
WARM FRONT ADVANCES NORTH INTO NORTHEAST OKLAHOMA AND NORTHWEST
ARKANSAS. THESE STORMS COULD ALSO BECOME SEVERE WITH SUPERCELLS
POSSIBLE NEAR THE WARM FRONT.

.SPOTTER ACTIVATION...
SPOTTER ACTIVATION MAY BE REQUIRED THIS MORNING AND THEN AGAIN LATE
THIS AFTERNOON ACROSS NORTHEAST OKLAHOMA AND NORTHWEST ARKANSAS.

.DISCUSSION...
SCATTERED ELEVATED THUNDERSTORMS MAY DEVELOP EARLY THIS MORNING AS
THE LOW LEVEL JET INCREASES ACROSS THE AREA. THE LOW LEVEL
CONVERGENCE ASSOCIATED WITH THE LOW LEVEL JET ALONG WITH WARM AIR
ADVECTION WILL PRODUCE ENOUGH LOW LEVEL LIFT TO PRODUCE SCATTERED
SHOWERS AND THUNDERSTORMS ACROSS NORTHEAST OKLAHOMA. THE
THUNDERSTORMS WILL THEN MOVE EAST INTO NORTHWEST ARKANSAS BY
MID-MORNING. ELEVATED INSTABILITIES ARE SUCH THAT SEVERE
THUNDERSTORMS WILL BE POSSIBLE WITH LARGE HAIL THE MAIN THREAT.

THE WARM FRONT CURRENTLY NEAR THE RED RIVER WILL MOVE NORTH INTO
NORTHEAST OKLAHOMA AND NORTHWEST ARKANSAS LATE THIS AFTERNOON. THE
AREA SOUTH OF THE WARM FRONT SHOULD REMAIN CAPPED.
HOWEVER...THUNDERSTORMS COULD DEVELOP ALONG AND NORTH OF THE WARM
LATE THIS AFTERNOON. ONCE AGAIN...THE AIRMASS WILL BE CAPABLE OF
SUPPORTING SEVERE THUNDERSTORMS. WHILE LARGE HAIL WILL BE THE
PRIMARY THREAT...SUPERCELLS WILL BE POSSIBLE NEAR THE WARM FRONT
WITH FAVORABLE WIND SHEAR AND INSTABILITY VALUES.

THREAT TABLE
VALID THROUGH 1200 UTC WEDNESDAY

AREA 1...NORTH OF A MCALESTER TO FORT SMITH LINE
THUNDERSTORM PROBABILITY...50
SEVERE PROBABILITY IF STORMS OCCUR...60
SIGNIFICANT SEVERE PROBABILITY IF STORMS OCCUR...20

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

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