MESOSCALE DISCUSSION 1313 NWS STORM PREDICTION CENTER NORMAN OK 0535 PM CDT FRI JUN 29 2012 AREAS AFFECTED...PORTIONS OF ERN SD...SWRN MN...NWRN IA CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY VALID 292235Z - 292330Z PROBABILITY OF WATCH ISSUANCE...20 PERCENT SUMMARY...AN ISOLATED SVR THREAT MAY CONTINUE INTO THE EVENING. WHILE CONVECTIVE TRENDS ACROSS THE AREA WILL CONTINUE TO BE MONITORED...THE NEED FOR A WW CURRENTLY APPEARS UNLIKELY. DISCUSSION...CONVECTION CONTINUES TO INITIATE ALONG A DIFFUSE STATIONARY FRONT THAT EXTENDS FROM S-CNTRL SD ENEWD TO E-CNTRL MN WITHIN A FAIRLY NARROW CORRIDOR WHERE PRECIPITATION/OVERTURNING HAS BEEN MINIMAL THROUGH THE DIURNAL HEATING CYCLE. THIS HAS CONTRIBUTED TO THE DEVELOPMENT OF MODERATE INSTABILITY -- MLCAPE VALUES OF 1000 TO 2000 J/KG -- WHICH MAY SUPPORT OCCASIONALLY ROBUST CONVECTIVE UPDRAFTS. SIOUX FALLS VWP DATA INDICATE 44 KT OF 0-6 KM BULK SHEAR...WHICH WILL SUPPORT OCCASIONALLY ORGANIZED CONVECTION...INCLUDING PERHAPS BRIEF/TRANSIENT SUPERCELL STRUCTURES. HOWEVER...WITH VISIBLE SATELLITE IMAGERY DEPICTING A LACK OF BOUNDARY-LAYER CU ACROSS THE AREA...INHIBITION MAY GREATLY LIMIT THE SPATIAL EXTENT OF ANY SVR THREAT IF A LARGER COLD POOL DOES NOT MATERIALIZE. AND...IN THE ABSENCE OF STRONGER LARGE-SCALE FORCING FOR ASCENT...STORM COVERAGE MAY BE LIMITED...THUS BREEDING LOW CONFIDENCE IN THE OPPORTUNITY FOR UPSCALE CONVECTIVE GROWTH. WHILE THE AREA WILL CONTINUE TO BE MONITORED...THE ANTICIPATED ISOLATED NATURE OF THE SVR THREAT OVER A FAIRLY NARROW CORRIDOR WILL LIKELY PRECLUDE THE NEED FOR WW ISSUANCE.
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