811 WWUS84 KTSA 041100 SPSTUL ARZ001-002-010-011-019-020-029-OKZ049-053>076-051100- EASTERN OKLAHOMA/NORTHWEST ARKANSAS HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE TULSA OK 600 AM CDT FRI MAY 4 2001 ...CHANCES OF THUNDERSTORMS INCREASING OVER EASTERN OKLAHOMA AND NORTHWEST ARKANSAS THIS AFTERNOON AND TONIGHT...BUT NO SEVERE WEATHER EXPECTED... AN UPPER LEVEL LOW PRESSURE AREA OVER THE SOUTHWEST U.S. AND INCREASING MOISTURE OVER THE SOUTHERN PLAINS WILL PROVIDE AN INCREASING CHANCE OF SHOWERS AND THUNDERSTORMS ACROSS EASTERN OKLAHOMA AND NORTHWEST ARKANSAS BY SATURDAY MORNING. A SLIGHT CHANCE OF THUNDERSTORMS WILL EXIST THIS AFTERNOON GENERALLY WEST OF HIGHWAY 75. SHOWERS AND THUNDERSTORMS ARE EXPECTED TO INCREASE IN THE EVENING AND SPREAD ACROSS MUCH OF EASTERN OKLAHOMA...POSSIBLY EXTENDING INTO NORTHWEST ARKANSAS BY EARLY SATURDAY MORNING. THE THUNDERSTORMS ARE EXPECTED TO REMAIN BELOW SEVERE LIMITS BUT DANGEROUS LIGHTNING AND BRIEF HEAVY RAIN WILL BE POSSIBLE. .SPOTTER ACTIVATION... STORM ACTIVATION IS NOT ANTICIPATED. $$ .DISCUSSION... IMPULSES FROM THE UPPER LOW OVER THE FOUR CORNERS WILL MOVE ACROSS WEST TEXAS AND WESTERN OKLAHOMA THIS AFTERNOON THEN INTO EASTERN OKLAHOMA AFTER MIDNIGHT. ASSOCIATED LOW LEVEL CONFLUENT FLOW IS EXPECTED TO ENHANCE VERTICAL MOTION AND HELP INITIATE CONVECTION THAT WILL SPREAD SLOWLY EASTWARD DURING THE EVENING AND NIGHT. THE AIRMASS WILL BE MODERATELY UNSTABLE DURING THE AFTERNOON WITH CAPE VALUES BETWEEN 500 AND 1000 J/KG...WHICH WILL BE DISTRIBUTED THINLY THROUGHOUT THE CONVECTIVE LAYER. THE AIRMASS WILL BECOME MORE STABLE DURING THE NIGHT...WHICH IS EXPECTED TO KEEP THUNDERSTORMS BELOW SEVERE LEVELS. THREAT TABLE VALID THROUGH 1200 UTC SATURDAY THREAT AREA...EASTERN OKLAHOMA AND NORTHWEST ARKANSAS THUNDERSTORM PROBABILITY...100 SEVERE PROBABILITY IF STORMS OCCUR...2 SIGNIFICANT SEVERE PROBABILITY IF STORMS OCCUR...0 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. A GRAPHICAL VERSION OF THIS OUTLOOK CAN BE FOUND AT: WWW.SRH.NOAA.GOV/TULSA  811 WWUS84 KTSA 041100 SPSTUL ARZ001-002-010-011-019-020-029-OKZ049-053>076-051100- EASTERN OKLAHOMA/NORTHWEST ARKANSAS HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE TULSA OK 600 AM CDT FRI MAY 4 2001 ...CHANCES OF THUNDERSTORMS INCREASING OVER EASTERN OKLAHOMA AND NORTHWEST ARKANSAS THIS AFTERNOON AND TONIGHT...BUT NO SEVERE WEATHER EXPECTED... AN UPPER LEVEL LOW PRESSURE AREA OVER THE SOUTHWEST U.S. AND INCREASING MOISTURE OVER THE SOUTHERN PLAINS WILL PROVIDE AN INCREASING CHANCE OF SHOWERS AND THUNDERSTORMS ACROSS EASTERN OKLAHOMA AND NORTHWEST ARKANSAS BY SATURDAY MORNING. A SLIGHT CHANCE OF THUNDERSTORMS WILL EXIST THIS AFTERNOON GENERALLY WEST OF HIGHWAY 75. SHOWERS AND THUNDERSTORMS ARE EXPECTED TO INCREASE IN THE EVENING AND SPREAD ACROSS MUCH OF EASTERN OKLAHOMA...POSSIBLY EXTENDING INTO NORTHWEST ARKANSAS BY EARLY SATURDAY MORNING. THE THUNDERSTORMS ARE EXPECTED TO REMAIN BELOW SEVERE LIMITS BUT DANGEROUS LIGHTNING AND BRIEF HEAVY RAIN WILL BE POSSIBLE. .SPOTTER ACTIVATION... STORM ACTIVATION IS NOT ANTICIPATED. $$ .DISCUSSION... IMPULSES FROM THE UPPER LOW OVER THE FOUR CORNERS WILL MOVE ACROSS WEST TEXAS AND WESTERN OKLAHOMA THIS AFTERNOON THEN INTO EASTERN OKLAHOMA AFTER MIDNIGHT. ASSOCIATED LOW LEVEL CONFLUENT FLOW IS EXPECTED TO ENHANCE VERTICAL MOTION AND HELP INITIATE CONVECTION THAT WILL SPREAD SLOWLY EASTWARD DURING THE EVENING AND NIGHT. THE AIRMASS WILL BE MODERATELY UNSTABLE DURING THE AFTERNOON WITH CAPE VALUES BETWEEN 500 AND 1000 J/KG...WHICH WILL BE DISTRIBUTED THINLY THROUGHOUT THE CONVECTIVE LAYER. THE AIRMASS WILL BECOME MORE STABLE DURING THE NIGHT...WHICH IS EXPECTED TO KEEP THUNDERSTORMS BELOW SEVERE LEVELS. THREAT TABLE VALID THROUGH 1200 UTC SATURDAY THREAT AREA...EASTERN OKLAHOMA AND NORTHWEST ARKANSAS THUNDERSTORM PROBABILITY...100 SEVERE PROBABILITY IF STORMS OCCUR...2 SIGNIFICANT SEVERE PROBABILITY IF STORMS OCCUR...0 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. A GRAPHICAL VERSION OF THIS OUTLOOK CAN BE FOUND AT: WWW.SRH.NOAA.GOV/TULSA