MESOSCALE DISCUSSION 0442
   NWS STORM PREDICTION CENTER NORMAN OK
   1041 AM CDT THU APR 11 2013
   
   AREAS AFFECTED...ERN MS THROUGH NWRN AL AND MIDDLE TN
   
   CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 
   
   VALID 111541Z - 111745Z
   
   PROBABILITY OF WATCH ISSUANCE...40 PERCENT
   
   SUMMARY...STORMS ARE EXPECTED TO UNDERGO A SLOW BUT GRADUAL INCREASE
   IN ORGANIZATION AND INTENSITY INTO THE AFTERNOON. PRIMARY THREAT
   WILL BE ISOLATED DAMAGING WIND...BUT ISOLATED TORNADOES CANNOT BE
   RULED OUT. AREA WILL CONTINUE TO BE MONITORED...AND ANY WW ISSUANCE
   WILL ULTIMATELY DEPEND ON CONVECTIVE TRENDS.
   
   DISCUSSION...EXPANSIVE SQUALL LINE EXTENDS FROM WEST OF NASHVILLE TN
   SSWWD THROUGH ERN MS INTO SERN LA. A FEW SMALL BOWING SEGMENTS AND
   MESO-VORTICES HAVE OCCASIONALLY BEEN OBSERVED WITHIN THE LINE...BUT
   OVERALL STORMS HAVE BEEN NON-SEVERE THIS MORNING. SFC MESOANALYSIS
   SHOW MOIST AXIS WITH DEWPOINTS FROM UPPER 60S OVER SERN MS/SRN AL TO
   NEAR 60 OVER THE TN VALLEY. RICHER LOW-LEVEL MOISTURE WILL ADVECT
   THROUGH SERN U.S. WARM SECTOR...BUT WIDESPREAD CLOUDS AND MODEST
   LAPSE RATES SHOULD LIMIT MLCAPE TO AROUND 1500 J/KG OVER THE GULF
   COASTAL STATES AND BELOW 1000 J/KG NORTHWARD INTO THE TN VALLEY.
   
   MORNING RAOB FROM BIRMINGHAM INDICATE A CAPPING INVERSION PRESENT
   JUST ABOVE 700 MB WHICH SHOULD TEND TO DELAY DEVELOPMENT OF MORE
   ROBUST DISCRETE ACTIVITY WITH ERN EXTENT INTO THE WARM SECTOR. THIS
   SUGGESTS MOST STORMS NEAR TERM WILL PROBABLY REMAIN CONFINED TO ZONE
   OF FORCING ALONG THE OUTFLOW BOUNDARY ASSOCIATED WITH THE SQUALL
   LINE. HOWEVER...RADAR TRENDS HAVE SHOWN AN INCREASE IN WARM SECTOR
   CONVECTION OVER SERN MS. HERE...INFLUX OF MT AIR...A FEW CLOUD
   BREAKS AND INFLUENCE FROM VORT MAX ROTATING THROUGH BASE OF UPPER
   TROUGH MAY SUPPORT MORE ROBUST DISCRETE STORMS. 
   
   INITIALLY PRIMARY THREAT IS EXPECTED TO BE DAMAGING WIND AS STORMS
   INTENSIFY AND BECOME BETTER ORGANIZED WITHIN THE ONGOING SQUALL
   LINE. HOWEVER...DEEPENING OF CONVECTION IN WARM SECTOR MAY
   EVENTUALLY OCCUR AS THE BOUNDARY LAYER GRADUALLY DESTABILIZES AND
   CAPPING INVERSION ERODES. HODOGRAPHS AND EFFECTIVE BULK SHEAR WILL
   REMAIN SUFFICIENT FOR A FEW EMBEDDED SUPERCELLS WITHIN THE LINE OR
   WITH ANY CONVECTION THAT MAY DEEPEN IN WARM SECTOR DURING THE
   AFTERNOON.
   
   ..DIAL/THOMPSON.. 04/11/2013
   
   
   ATTN...WFO...OHX...BMX...HUN...MEG...JAN...
   
   LAT...LON   32498759 32358885 32718914 33958827 34958766 36158663
               36008589 34648640 33498695 32498759