MESOSCALE DISCUSSION 2100
   NWS STORM PREDICTION CENTER NORMAN OK
   1132 PM CDT FRI SEP 02 2011
   
   AREAS AFFECTED...SOUTHERN LA AND EXTREME SOUTHERN MS/AL
   
   CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 
   
   VALID 030432Z - 030630Z
   
   NORTH-NORTHEAST PERIPHERAL BANDS OF TROPICAL STORM LEE MAY POSE AN
   ISOLATED/MAINLY BRIEF TORNADO THREAT ACROSS SOUTHERN LA COASTAL
   AREAS /ESPECIALLY SOUTHEAST LA/ AND PERHAPS EXTREME SOUTHERN MS/AL
   THROUGH THE EARLY MORNING HOURS OF SATURDAY. WHILE ANY THREAT MAY
   REMAIN VERY ISOLATED...A TORNADO WATCH MAY NEED TO BE CONSIDERED.
   
   AS PER LATEST NHC GUIDANCE...TROPICAL STORM LEE IS EXPECTED TO
   CONTINUE A SLOW GENERAL NORTHWARD DRIFT TOWARD THE LA COAST AS IT
   GRADUALLY INTENSIFIES THROUGH EARLY SATURDAY. THE NORTH-NORTHEAST
   PERIPHERAL WIND FIELD HAS SHOWN A GRADUAL STRENGTHENING INLAND
   THROUGH THE EVENING...AS PER THE 01Z OBSERVED RAOB FROM SLIDELL LA
   AND TRENDS OF LIX/MOB WSR-88D VWP DATA...WITH SOME ADDITIONAL
   STRENGTHENING ANTICIPATED OVERNIGHT AS TROPICAL STORM LEE MOVES A
   BIT CLOSER/MODESTLY INTENSIFIES.
   
   IT SEEMS PROBABLE THAT WEAK BUOYANCY/LOW-LEVEL LAPSE RATES INLAND
   AMID CLOUD COVER/PRECIPITATION WILL TEND TO LIMIT THE
   CERTAINTY/MAGNITUDE OF A TORNADO THREAT...ALTHOUGH
   LIGHTNING-PRODUCING CONVECTIVE BANDS CONTINUE TO PERSIST LATE THIS
   EVENING SOUTH OF THE HOUMA VICINITY. NONETHELESS...ADJUSTMENTS TO
   THE AFOREMENTIONED 01Z LIX RAOB AND LATEST LIX/MOB WSR-88D VWP DATA
   IS INDICATIVE OF 0-1 KM SRH ON THE ORDER OF 150-225 M2/S2...GIVEN
   THE EAST-SOUTHEASTERLY COMPONENT OF THE LOW-LEVEL FLOW IN VICINITY
   OF A NEAR-SHORE CONFLUENCE AXIS. WITH A VERY MOIST AIRMASS /MIDDLE
   70S F SURFACE DEWPOINTS/...THE DEGREE OF SHEAR/SRH WILL PROVIDE THE
   POTENTIAL FOR EMBEDDED LOW-TOPPED SUPERCELLS CAPABLE OF ISOLATED
   TORNADOES.
   
   ..GUYER.. 09/03/2011
   
   
   ATTN...WFO...MOB...LIX...LCH...
   
   LAT...LON   29369216 30079220 30549174 30699100 30748989 30758886
               30658830 30378803 30218803 29098880 28948948 28879014
               28809079 29009175 29369216