MESOSCALE DISCUSSION 0550

 MESOSCALE DISCUSSION 0550
   NWS STORM PREDICTION CENTER NORMAN OK
   0156 PM CDT SUN APR 15 2012
   
   AREAS AFFECTED...CNTRL/N-CNTRL IA...SRN MN
   
   CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 
   
   VALID 151856Z - 152030Z
   
   PORTIONS OF CNTRL/N-CNTRL IA AND SRN MN ARE BEING MONITORED FOR THE
   POSSIBLE ISSUANCE OF A TORNADO WATCH THIS AFTERNOON.
   
   SFC ANALYSIS INDICATES A COLD FRONT TRAILING SWD FROM A TRIPLE POINT
   30 MILES SE OF SIOUX FALLS SD...WITH A WARM FRONT ARCING ENEWD FROM
   THE TRIPLE POINT ACROSS SRN MN INTO W-CNTRL WI. INHIBITION WITHIN
   THE WARM SECTOR CONTINUES TO ERODE...WITH THE MODIFIED
   MINNEAPOLIS-ST PAUL 18Z RAOB ACCOUNTING FOR SFC OBS IN THE WARM
   SECTOR INDICATING UPWARDS OF 1000 J/KG OF MLCAPE WITH NEAR-ZERO
   CINH. A WELL-DEFINED AXIS OF CONFLUENCE ALIGNS WITH THE COLD
   FRONT...WITH SUPPORTING LOW-LEVEL CONVERGENCE POTENTIALLY BECOMING
   RESPONSIBLE FOR CONVECTIVE INITIATION BETWEEN 1930Z AND 21Z AS
   DIABATIC HEATING CONTINUES TO THE EAST. ALREADY...VISIBLE SATELLITE
   IMAGERY DEPICTS MODEST VERTICAL DEVELOPMENT WITHIN BANDS OF CUMULUS
   NEAR THE COLD FRONT IN WRN IA. THIS COULD EVOLVE INTO DEEPER
   CONVECTION WITHIN THE NEXT COUPLE OF HOURS. ONCE STORMS FORM...THEY
   WILL HAVE THE POTENTIAL TO QUICKLY BECOME SVR GIVEN EFFECTIVE BULK
   SHEAR MAGNITUDES OF 50-70 KT. LOW-LEVEL SHEAR WILL BE SUFFICIENT FOR
   TORNADIC SUPERCELLS...PARTICULARLY NEAR THE WARM FRONT WHERE SFC
   WINDS REMAIN RELATIVELY BACKED.