MESOSCALE DISCUSSION 2168
   NWS STORM PREDICTION CENTER NORMAN OK
   0416 AM CST MON DEC 17 2012
   
   AREAS AFFECTED...FAR SERN MS/SWRN-SOUTH CENTRAL AL/WRN FL PANHANDLE
   
   CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 
   
   VALID 171016Z - 171215Z
   
   PROBABILITY OF WATCH ISSUANCE...40 PERCENT
   
   SUMMARY...A SEVERE WEATHER THREAT /DAMAGING WINDS AND/OR A TORNADO/
   MAY BE DEVELOPING EARLY THIS MORNING ALONG THE COASTAL AREAS OF SERN
   MS...SWRN AL AND THE WRN FL PANHANDLE...WITH POTENTIAL TO MOVE A
   LITTLE FARTHER INLAND OVER SWRN AL/WRN FL PANHANDLE.  WW ISSUANCE IS
   AT 40 PERCENT SINCE UNCERTAINTY REMAINS IN THE OVERALL STORM
   COVERAGE INTO THE MORNING.
   
   DISCUSSION...TRENDS DURING THE OVERNIGHT/EARLY THIS MORNING SHOWED A
   PORTION OF THE CONVECTIVE OUTFLOW BOUNDARY THAT HAD MOVED INTO THE
   NRN GULF OF MEXICO HAS RETURNED NWD...AND WAS IMPINGING UPON THE
   COASTAL AREAS OF FAR SERN MS/SWRN AL /DAUPHIN ISLAND VICINITY/.
   REGIONAL RADAR IMAGERY SHOWED CONVECTIVE CELLS MOVING INTO SRN
   MOBILE COUNTY FROM OFFSHORE...WITH LIGHTNING ALSO DETECTED FARTHER
   SSW OVER THE CHANDELEUR ISLANDS...WHERE A TRAILING PORTION OF THE
   OUTFLOW BOUNDARY HAD BECOME ORIENTED NNE-SSW ALONG AND OFFSHORE OF
   SERN LA. 
   
   SWLY MIDLEVEL WINDS OVER THE LOWER MS VALLEY-CENTRAL GULF COAST
   STATES WILL CONTINUE TO STRENGTHEN THIS MORNING AS A PROGRESSIVE
   SHORTWAVE TROUGH...CURRENTLY MOVING EWD ACROSS THE OZARKS-ARKLATEX
   REGION PER MOISTURE CHANNEL IMAGERY...BECOMES NEGATIVELY TILTED. 
   THESE WINDS AND 30-35 KT SSWLY LLJ SUPPORT BULK SHEAR OF 40-55 KT
   FOR ORGANIZED STORMS...WHILE EFFECTIVE SRH OF 100-200 M2/S2 INVOF
   THE NWD MOVING BOUNDARY INTO THE DISCUSSION AREA WILL SUPPORT THE
   POTENTIAL FOR LOW LEVEL ROTATION/AT LEAST A BRIEF TORNADO.  MUCAPE
   OF 200-400 J/KG N OF THE RETREATING BOUNDARY AND AOA 500 J/KG IN THE
   WARM SECTOR SHOULD REMAIN MEAGER THROUGH THE MORNING AND WILL BE THE
   MAIN LIMITING FACTOR FOR GREATER TSTM/SVR COVERAGE.  AN ADDITIONAL
   THREAT FOR AT LEAST A FEW STRONG TO SEVERE STORMS COULD DEVELOP
   ALONG THE TRAILING EXTENT OF OVERNIGHT ELEVATED CONVECTION THAT
   SHOULD MOVE INTO SWRN AL BETWEEN 11-12Z.
   
   ..PETERS/EDWARDS.. 12/17/2012
   
   
   ATTN...WFO...TAE...MOB...LIX...
   
   LAT...LON   29638923 30718891 31328798 31258688 30858631 30138664
               30068723 29768820 29458862 29638923