MESOSCALE DISCUSSION 0273
   NWS STORM PREDICTION CENTER NORMAN OK
   0139 AM CDT MON MAR 12 2007
   
   AREAS AFFECTED...TX HILL COUNTRY TO MIDDLE/UPPER TX COAST
   
   CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY 
   
   VALID 120639Z - 120845Z
   
   POTENTIAL FOR ISOLATED SEVERE STORMS IS EXPECTED TO CONTINUE THROUGH
   THE EARLY MORNING HOURS ACROSS DISCUSSION AREA.  A WW IS NOT
   ANTICIPATED.
   
   AS OF 0630Z...REGIONAL RADAR IMAGERY INDICATED A QUASI-LINEAR
   CONVECTIVE SYSTEM /QLCS/...THE LEADING EDGE OF WHICH EXTENDED FROM
   VICINITY OF MCV OVER TRAVIS COUNTY SWWD TO LA SALLE AND WEBB
   COUNTIES...WITH A GENERAL SYSTEM MOTION OF 310/20 KT.  MESOSCALE
   FORCING FOR ASCENT ASSOCIATED WITH MCV COUPLED WITH MOIST AND
   UNSTABLE...INFLOW AIR MASS /MLCAPES OF 500-1000 J PER KG/ WILL
   LIKELY MAINTAIN THIS SYSTEM INTO PARTS OF THE MIDDLE AND UPPER TX
   COAST BY 12Z.
   
   WHILE A RECENT WIND GUST TO 54 KT WAS OBSERVED AT KSSF...IT APPEARS
   THAT A MORE ORGANIZED DAMAGING WIND THREAT MAY BE LIMITED BY: 1)
   MODEST TROPOSPHERIC WIND FIELDS AND RESULTANT SYSTEM MOTION OF ONLY
   20-25 KT AND 2) A RELATIVELY MOIST ENVIRONMENT WHICH SHOULD LIMIT
   EVAPORATIVE COOLING/DOWNDRAFT STRENGTH.  THE GREATEST THREAT OF
   LOCALLY DAMAGING WINDS APPEARS TO BE JUST S OF MCV WHERE GRADIENT
   FLOW AND/OR ESTABLISHMENT OF A REAR INFLOW JET /PER RECENT SAT VWP
   OBSERVATIONS/ WILL ENHANCE DOWNWARD MOMENTUM TRANSFER.
   
   EMBEDDED SUPERCELL STRUCTURES /SIMILAR TO THAT OVER BASTROP COUNTY
   AS OF 0630Z/ MAY WELL PERSIST IN SAME GEOMETRIC LOCATION RELATIVE TO
   QLCS OWING TO ENHANCED WAA /AND LOW-LEVEL SHEAR/ ENE OF MCV. 
   CURRENT LEDBETTER PROFILER INDICATES MODEST SRH OF AROUND 200 M2/S2
   THROUGH THE LOWEST 1 KM AGL...WHICH WHEN COUPLED WITH THE MARGINAL
   INSTABILITY AND MOIST BOUNDARY LAYER...SUGGEST SOME THREAT OF A
   BRIEF TORNADO.  THIS THREAT SHOULD REMAIN LIMITED OWING TO: 1)
   POTENTIAL FOR QLCS TO OVERTAKE MORE DISCRETE CELLS...AND 2) NOTION
   THAT STRONGER INSTABILITY WILL REMAIN REMOVED TO THE S FROM THE
   STRONGER LOW-LEVEL SHEAR ASSOCIATED WITH RETREATING SYNOPTIC WARM
   FRONT AND ENHANCEMENT IN WAA ZONE ENE OF MCV.
   
   ..MEAD.. 03/12/2007
   
   
   ATTN...WFO...HGX...CRP...EWX...
   
   28819835 29469768 29839760 30049761 30349749 30449710
   30279628 29849533 29489529 28889585 28439665 28129732
   28209800