SPC AC 290613

   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0113 AM CDT FRI APR 29 2016

   VALID 291200Z - 301200Z

   ...THERE IS AN ENH RISK OF SVR TSTMS ACROSS PORTIONS OF OK/NORTH TX
   TO THE ARKLATEX...

   ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS THE SOUTHERN PLAINS TO
   ARKLATEX/LOWER MS RIVER VALLEY...

   ...THERE IS A MRGL RISK OF SVR TSTMS ACROSS THE CENTRAL/SOUTHERN
   PLAINS TO ARKLATEX/LOWER MS RIVER VALLEY...

   ...SUMMARY...
   SEVERE THUNDERSTORMS ARE LIKELY TODAY AND TONIGHT ESPECIALLY ACROSS
   PARTS OF OKLAHOMA AND TEXAS TO THE ARKLATEX REGION AND LOWER
   MISSISSIPPI RIVER VALLEY.

   ...SYNOPSIS...
   AN AMPLIFIED LARGE-SCALE PATTERN OVER MUCH OF THE CONUS WILL BE
   HIGHLIGHTED BY THE NORTHEASTWARD-ADVANCEMENT OF A
   CLOSED/INCREASINGLY NEGATIVE-TILT TROUGH FROM THE FOUR CORNERS AREA
   EARLY TODAY TO THE CENTRAL HIGH PLAINS TONIGHT.

   ...SOUTHERN PLAINS TO ARKLATEX/LOWER MS RIVER VALLEY...
   A HIGHLY COMPLEX FORECAST SCENARIO IS EXPECTED PARTICULARLY ACROSS
   OK/NORTH TX THROUGH THE AFTERNOON/EVENING...WITH ADMITTEDLY
   BELOW-AVERAGE CONFIDENCE IN FORECAST/SPATIAL DETAILS. THIS IS
   LARGELY ATTRIBUTABLE TO UNCERTAINTIES REGARDING THE
   EXTENSIVENESS/PERSISTENCE OF EARLY-DAY CONVECTION AND APPRECIABLE
   SHORTER-TERM /24-36 HOUR/ DETERMINISTIC AND ENSEMBLE GUIDANCE
   VARIABILITY.

   SCATTERED THUNDERSTORMS...SOME POTENTIALLY STRONG/SEVERE AND CAPABLE
   OF HAIL...ARE EXPECTED TO BE ONGOING THIS MORNING FROM THE TX/OK
   PANHANDLES INTO PARTS OF THE BODY OF OK AND THE ARKLATEX REGION.
   THESE STORMS WILL GENERALLY BE FOCUSED ALONG A NORTHWARD-SHIFTING
   WARM FRONT...WHICH SHOULD ROUGHLY BE SITUATED ACROSS
   WEST-CENTRAL/SOUTH-CENTRAL OK AND THE OK/TX RED RIVER VICINITY AND
   ARKLATEX THIS AFTERNOON...ALTHOUGH PERSISTENT EARLY-DAY
   CONVECTION/CLOUD COVER AND RELATED DIURNAL DIFFERENTIAL HEATING WILL
   BE FACTORS IN EXACTLY WHERE THE WARM FRONT IS EFFECTIVELY LOCATED
   LATER TODAY. MIDDLE 60S TO NEAR 70F SURFACE DEWPOINTS WILL BECOME
   INCREASINGLY ESTABLISHED THIS AFTERNOON NEAR/SOUTH OF THIS WARM
   FRONT...EAST OF AN EASTWARD-MOVING TX/SOUTHERN OK DRYLINE...AND EAST
   OF A PACIFIC COLD FRONT WHICH WILL ACCELERATE EAST-SOUTHEASTWARD
   TONIGHT ACROSS KS/OK AND WESTERN NORTH TX.

   DEVELOPMENT/INTENSIFICATION OF SURFACE-BASED STORMS WILL BE POSSIBLE
   THIS AFTERNOON/EARLY EVENING AS FAR WEST AS WEST/SOUTHWEST OK IN
   VICINITY OF A SURFACE TRIPLE POINT...AND AS FAR EAST AS AR/LOWER MS
   RIVER VALLEY WHERE MORNING STORMS COULD PERSIST/POSSIBLY GROW
   UPSCALE DURING THE DAY. CURRENT THINKING IS THAT SEVERE HAIL WILL BE
   THE MOST COMMON SEVERE THREAT OVERALL...POTENTIALLY FROM A MULTIPLE
   ROUND OF STORMS IN SOME SUB-REGIONAL AREAS INCLUDING PARTS OF OK AND
   THE ARKLATEX. TORNADO POTENTIAL...AT LEAST IN A CONDITIONAL
   SENSE...SHOULD BE MAXIMIZED IN A ROUGHLY WSW/ESE-ORIENTED
   NEAR-WARM-FRONT CORRIDOR ACROSS THE SOUTHERN HALF OF OK/FAR NORTH TX
   AND PARTS OF THE ARKLATEX. ALTHOUGH LOW-LEVEL SHEAR FORECASTS VARY
   CONSIDERABLY AMONG AVAILABLE RAP/GFS AND MORE-AGGRESSIVE NAM
   GUIDANCE...SOMEWHAT HIGHER TORNADO PROBABILITIES /10 PERCENT/ APPEAR
   WARRANTED NEAR THE WARM FRONT...BUT SUBSEQUENT SPATIAL ADJUSTMENTS
   CAN BE EXPECTED PENDING MESOSCALE DETAILS AND A RESOLUTION TO
   CURRENT FORECAST UNCERTAINTIES.

   FARTHER SOUTH...OF SOMEWHAT GREATER SPATIAL/TIMING FORECAST
   CERTAINTY WILL BE FOR STORMS TO DEVELOP/INCREASE THIS AFTERNOON
   ACROSS MUCH OF NORTH/CENTRAL TX IN VICINITY OF THE NNE/SSW-ORIENTED
   DRYLINE. STRONG VERTICAL SHEAR /40+ KT/ AND MODERATE INSTABILITY
   WILL SUPPORT SUPERCELLS CAPABLE OF LARGE HAIL AND POSSIBLY A COUPLE
   OF TORNADOES THIS AFTERNOON AND EVENING.

   ..GUYER/PICCA.. 04/29/2016

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