MESOSCALE DISCUSSION 0489
   NWS STORM PREDICTION CENTER NORMAN OK
   0732 PM CDT THU MAR 27 2008
   
   AREAS AFFECTED...NERN OK...NWRN AR...S CNTRL THROUGH E CNTRL MO AND
   S CNTRL IL
   
   CONCERNING...SEVERE THUNDERSTORM WATCH 138...139...
   
   VALID 280032Z - 280200Z
   
   THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH
   138...139...CONTINUES.
   
   THREAT FOR MAINLY LARGE HAIL WILL PERSIST INTO MUCH OF THE EVENING
   FROM NERN OK...SRN THROUGH E CNTRL MO INTO S CNTRL IL. AN ISOLATED
   TORNADO OR TWO REMAINS POSSIBLE WITH SURFACE BASED DISCRETE STORMS
   FROM NERN OK THROUGH SRN MO NEXT HOUR OR TWO.
   
   COLD FRONT EXTENDS FROM SRN IND THROUGH SRN IL TO JUST SOUTH OF ST
   LOUIS THEN SWWD THROUGH SWRN MO...NERN AND SWRN OK. WARM SECTOR
   SOUTH OF THIS BOUNDARY REMAINS MODERATELY UNSTABLE WITH MLCAPE FROM
   1000 TO 1500 J/KG ALONG WITH STEEP LAPSE RATES. AS EVIDENCED ON THE
   00Z RAOB FROM SPRINGFIELD...STRONG HEATING AND BOUNDARY LAYER MIXING
   WEAKENED THE CAP ENOUGH FOR SURFACE BASED STORMS TO DEVELOP WITHIN
   THE ZONE OF LOW LEVEL CONVERGENCE ALONG FRONT FROM NERN OK INTO E
   CNTRL MO. LOW LEVEL HODOGRAPHS ARE SMALL OWING TO MODEST AND VEERED
   LOW LEVEL WINDS. HOWEVER...EFFECTIVE BULK SHEAR OF 40 TO 50 KT HAS
   SUPPORTED SUPERCELL STRUCTURES. THE MAIN THREAT WITH THESE STORMS IS
   LARGE HAIL. ISOLATED BRIEF TORNADOES HAVE BEEN REPORTED OVER NERN OK
   AND SRN MO. GIVEN THE RELATIVELY LARGE TEMPERATURE-DEWPOINT
   SPREADS...SURFACE BASED INVERSION WILL BECOME MORE PRONOUNCED WITH
   ONSET OF NOCTURNAL COOLING. THIS SUGGEST ANY REMAINING TORNADO
   THREAT WILL GRADUALLY DECREASE IN THIS REGION. STORMS ARE SHOWING A
   TENDENCY TO BACKBUILD DOWN THE FRONT IN ERN OK. HOWEVER...SRN EXTENT
   OF DEVELOPMENT IN WARM SECTOR WILL BE LIMITED BY A STRENGTHENING
   CAP...ESPECIALLY AS THE BOUNDARY LAYER COOLS.
   
   SHORT TERM TORNADO THREAT APPEARS A LITTLE HIGHER WITH SUPERCELLS
   ACROSS SERN MO NEXT HOUR OR TWO WHERE TEMPERATURE-DEWPOINT SPREADS
   ARE LOWER AND 0-1 KM HODOGRAPHS ARE LARGER ON NOSE OF THE LOW LEVEL
   JET.
   
   ..DIAL.. 03/28/2008
   
   
   ATTN...WFO...LSX...LZK...SGF...TSA...
   
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