MESOSCALE DISCUSSION 0472
   NWS STORM PREDICTION CENTER NORMAN OK
   0552 PM CDT MON APR 13 2009
   
   AREAS AFFECTED...NRN AL...PORTIONS OF SRN TN/NWRN GA
   
   CONCERNING...TORNADO WATCH 151...
   
   VALID 132252Z - 132345Z
   
   THE SEVERE WEATHER THREAT FOR TORNADO WATCH 151 CONTINUES.
   
   SCATTERED CONVECTION DEVELOPING ALONG A LOW-LEVEL CONFLUENCE AXIS
   AHEAD OF A COLD FRONT MAY POSE A SEVERE HAIL/DAMAGING WIND THREAT
   INTO EARLY EVENING. OVERALL TORNADIC POTENTIAL APPEARS LIMITED...BUT
   A BRIEF/WEAK TORNADO REMAINS POSSIBLE...MOST LIKELY TOWARDS THE
   CUMBERLAND PLATEAU. A REPLACEMENT SEVERE TSTM WATCH IS BEING
   CONSIDERED FOR THE REGION.
   
   RECENT RADAR/SATELLITE IMAGERY INDICATE SCATTERED CONVECTION HAS
   DEVELOPED WITHIN A CONFLUENCE AXIS FROM S-CNTRL MS NEWD TOWARD THE
   CUMBERLAND PLATEAU IN ERN TN. MODIFIED RUC SOUNDINGS/18Z JAN RAOB
   SUGGEST THAT TOTAL CAPE WILL BE LIMITED BY MID-LEVEL INVERSION
   BETWEEN 600-500 MB...AND THIS WILL LIKELY MITIGATE WHAT MIGHT
   OTHERWISE BE A MORE ROBUST SEVERE THREAT. NEVERTHELESS...STRONG
   SPEED SHEAR /WITH EFFECTIVE SHEAR VALUES OF 50-60 KT/ AND STEEP
   LOW-LEVEL LAPSE RATES SHOULD SUPPORT UPDRAFT ORGANIZATION WITH
   ATTENDANT THREATS FOR SEVERE HAIL/DAMAGING WINDS. STRAIGHT-LINE
   HODOGRAPHS WILL CONTINUE TO RESULT IN SPLITTING CELLS...AS EVIDENCED
   BY AN EARLIER SPLIT AND LEFT-MOVING CELL NOW ENTERING WALKER COUNTY
   AL. ALTHOUGH OVERALL TORNADIC THREAT SHOULD BE MITIGATED BY
   MODEST/UNIDIRECTIONAL LOW-LEVEL FLOW...POTENTIAL FOR A TORNADO OR
   TWO COULD EXIST OVER THE CUMBERLAND PLATEAU WHERE LOW-LEVEL WINDS
   REMAIN SLIGHTLY BACKED AND SURFACE DEW POINT DEPRESSIONS ARE LOWER.
   
   ..GRAMS.. 04/13/2009
   
   
   ATTN...WFO...MRX...FFC...OHX...BMX...HUN...MEG...JAN...
   
   LAT...LON   35318609 35808510 35698447 35268430 34888479 34248559
               33818622 33108734 32898814 33088868 33808844 34908671
               35318609