MESOSCALE DISCUSSION 2153
   NWS STORM PREDICTION CENTER NORMAN OK
   0519 AM CDT THU OCT 29 2009
   
   AREAS AFFECTED...SERN TX
   
   CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 
   
   VALID 291019Z - 291145Z
   
   TSTMS MAY GRADUALLY DEVELOP FROM ONGOING SHOWER ACTIVITY THIS
   MORNING.  SHOULD THIS OCCUR...ENVIRONMENT WILL FAVOR SUPERCELLS WITH
   THE THREAT FOR A TORNADO OR TWO.  CONVECTIVE TRENDS ARE BEING
   MONITORED FOR A POSSIBLE WW.
   
   TRENDS IN REGIONAL RADAR IMAGERY INDICATE DEEPENING/INCREASING
   SHOWER ACTIVITY FROM AUS EWD THROUGH CLL TO NEAR OR JUST S OF UTS. 
   BASED ON MODEL GUIDANCE AND SATELLITE IMAGERY...IT APPEARS THAT THE
   SLOW EWD MIGRATION OF LARGE-SCALE TROUGH MAY BE PROVIDING SUFFICIENT
   BACKGROUND ASCENT TO OVERCOME LINGERING CONVECTIVE INHIBITION.  THIS
   TREND SHOULD CONTINUE THROUGH THE MORNING.  AMBIENT AIR MASS IS
   QUITE MOIST WITH DEWPOINTS IN THE MID 70S...CONTRIBUTING TO MLCAPE
   OF 1000-1500 J/KG BASED ON RUC PROXIMITY SOUNDINGS.
   
   AREA VWP/PROFILER DATA INDICATE NOTABLE DIRECTIONAL/SPEED SHEAR IN
   THE LOWEST 0.5 KM...WITH A GRADUAL INCREASE IN SPEED SHEAR ABOVE
   THAT LAYER.  THIS IS RESULTING IN RELATIVELY STRONG NEAR-GROUND
   SHEAR /I.E. 30-35 KT THROUGH THE LOWEST KM/...WHICH IS MORE THAN
   SUFFICIENT FOR UPDRAFT ROTATION.  GIVEN THE MOIST/LOW LCL AIR MASS
   IN PLACE...THE THREAT WILL EXIST FOR TORNADOES WITH ANY SUPERCELLS
   THAT CAN BECOME ESTABLISHED.
   
   ..MEAD.. 10/29/2009
   
   
   ATTN...WFO...LCH...SHV...HGX...FWD...EWX...
   
   LAT...LON   29279537 29499623 30269676 30779666 31189584 31319534
               31019444 30409391 29649413 29279537