SPC AC 090605
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0105 AM CDT TUE MAY 09 2006
   
   VALID 091200Z - 101200Z
   
   ...THERE IS A MDT RISK OF SVR TSTMS ACROSS EASTERN OK AND INTO WRN
   AR/FAR SRN MO...
   
   ...THERE IS A SLGT RISK OF SVR TSTMS FROM THE SRN PLAINS EWD INTO
   THE MIDDLE AND LOWER MS VALLEY...
   
   ...SYNOPSIS...
   LARGE MID-LEVEL TROUGH IS FORECAST TO MOVE SLOWLY EWD OUT OF THE
   ROCKIES AND INTO THE CENTRAL CONUS THIS PERIOD.  IN CONJUNCTION...A
   LARGE BELT OF ENHANCED CYCLONIC FLOW /40 TO 55 KT/ WILL SPREAD EWD
   INTO THE CENTRAL AND SRN PLAINS/MIDDLE AND LOWER MO VALLEY REGION.
   
   AT THE SURFACE...A COLD FRONT WILL MOVE EWD TOWARD THE MS VALLEY
   DURING THE DAY...WHILE SAGGING SEWD ACROSS MO/OK AND N TX THROUGH
   THE AFTERNOON. BY THE END OF THE PERIOD...FRONT SHOULD EXTEND FROM
   THE UPPER GREAT LAKES SWWD ACROSS THE MIDDLE MO VALLEY INTO CENTRAL
   TX.
   
   ...ERN OK/SRN MO/NERN TX/AR/NRN LA AND INTO THE MID MS VALLEY...
   THOUGH A RELATIVELY WIDESPREAD/SIGNIFICANT SEVERE WEATHER EVENT IS
   FORECAST TO EVOLVE THIS PERIOD...DETAILS REGARDING LOCATION OF
   GREATER THREAT AREAS REMAIN DIFFICULT TO DISCERN ATTM DUE TO ONGOING
   MCS ACROSS KS ATTM.  AT THE START OF THE PERIOD...AN OUTFLOW
   BOUNDARY IS EXPECTED OVER NRN OR CENTRAL OK...WHILE STORMS SHOULD BE
   ONGOING N OF THIS BOUNDARY ACROSS PARTS OF KS/NRN OK/MO.
   
   S OF THIS CONVECTION...VERY MOIST AIRMASS SPREADING NWD COMBINED
   WITH DAYTIME HEATING AND VERY STEEP LAPSE RATES/EML SPREADING EWD
   ACROSS WARM SECTOR WILL RESULT IN EXTREME INSTABILITY --
   PARTICULARLY ACROSS PARTS OF OK/AR/N TX.  CONVECTION IS EXPECTED TO
   DEVELOP BY AFTERNOON -- EITHER ALONG SAGGING COLD FRONT AND/OR
   CONVECTIVE OUTFLOW ACROSS THE ERN HALF OF OK AND INTO AR.  STORMS
   POSSIBLY ONGOING ACROSS CENTRAL OR ERN MO SHOULD ALSO INTENSIFY AS
   UNDISTURBED AIRMASS AHEAD OF STORMS BECOMES MODERATELY UNSTABLE.  
   
   ALONG WITH DEGREE OF INSTABILITY...LOW-LEVEL VEERING BENEATH
   MODERATELY-STRONG MID-LEVEL WLYS WILL RESULT IN VERY FAVORABLE
   KINEMATIC ENVIRONMENT FOR ROTATING/SUPERCELL STORMS.  EXPECT
   WIDESPREAD THREAT FOR VERY LARGE HAIL...ALONG WITH LOCALLY DAMAGING
   WINDS. ISOLATED TORNADOES ALSO APPEAR LIKELY -- PARTICULARLY INVOF
   OUTFLOW BOUNDARY.
   
   WITH TIME...STORMS MAY ORGANIZE IN A MORE LINEAR FASHION ALONG
   FRONT...WITH THREAT FOR DAMAGING WINDS LIKELY TO INCREASE IN
   ADDITION TO ONGOING THREAT FOR LARGE HAIL AND ISOLATED TORNADOES. 
   AS LOW-LEVEL JET DEVELOPS OVERNIGHT...EXPECT STORMS TO
   INCREASE/SPREAD ACROSS MO/AR AND EWD INTO THE MID MS VALLEY/SEWD
   ACROSS NERN TX AND NRN LA THROUGH THE END OF THE PERIOD.
   
   ...PARTS OF CENTRAL AND S TX...
   CONDITIONAL SEVERE THREAT APPEARS TO EXIST ROUGHLY ALONG THE
   INTERSTATE 35 CORRIDOR FROM NEAR ACT SWWD TO THE RIO GRANDE...AS
   STRONG DAYTIME HEATING RESULTS IN A DEEP MIXED LAYER.  THOUGH CAP
   SHOULD HOLD THROUGH MUCH OF THE AFTERNOON...DEEP MIXING COMBINED
   WITH WEAK HEIGHT FALLS MAY BE SUFFICIENT FOR LOCAL CAP BREACHES --
   AND THUS ISOLATED STORMS.  PRESUMING THAT STORMS
   DEVELOP...SHEAR/INSTABILITY COMBINATION WILL BE SUFFICIENT FOR
   HIGH-BASED SUPERCELLS...WITH MAIN THREATS LARGE HAIL AND LOCALLY
   DAMAGING GUSTS.  STORMS SHOULD DIMINISH AFTER SUNSET AS BOUNDARY
   LAYER COOLS AND CAP BECOMES RE-ESTABLISHED.
   
   ...WRN OK/TX PANHANDLE AND VICINITY...
   ISOLATED AFTERNOON THUNDERSTORMS MAY DEVELOP IN POST-FRONTAL AIRMASS
   WHERE NELY UPSLOPE FLOW IS EXPECTED.  STRONG DEEP-LAYER SHEAR
   COMBINED WITH 500 TO 1500 J/KG MEAN-LAYER CAPE WILL BE SUFFICIENT
   FOR SUPERCELLS...WITH MAIN THREAT LIKELY TO BE HAIL.  STORMS SHOULD
   DIMINISH DURING THE EVENING WITH THE LOSS OF DAYTIME HEATING.
   
   ..GOSS.. 05/09/2006
   
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