MESOSCALE DISCUSSION 1228
   NWS STORM PREDICTION CENTER NORMAN OK
   0355 AM CDT THU JUN 21 2007
   
   AREAS AFFECTED...PARTS OF SRN MN
   
   CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 
   
   VALID 210855Z - 211030Z
   
   TRENDS ARE BEING MONITORED FOR AN INCREASING SEVERE THREAT AND THE
   POSSIBILITY OF A WW.
   
   IT SEEMS TO BE COMING APPARENT THAT MAIN CONVECTIVE CLUSTER...IF
   ANY...WILL CONTINUE TO GRADUALLY EVOLVE FARTHER TO THE WEST...
   ACROSS PARTS OF THE DAKOTAS...ASSOCIATED WITH A COUPLE OF UPPER
   IMPULSES PROGRESSING AROUND CREST OF UPPER RIDGE TO THE EAST OF THE
   NORTHERN ROCKIES.  HOWEVER...LARGE-SCALE ASCENT ASSOCIATED WITH
   LOW-LEVEL WARM ADVECTION DOWNSTREAM OF THESE FEATURES...AND IN THE
   WAKE OF VIGOROUS UPPER TROUGH PROGRESSING THROUGH THE GREAT LAKES
   ...APPEARS LIKELY TO MAINTAIN CONVECTIVE DEVELOPMENT ACROSS SOUTHERN
   MINNESOTA THROUGH AT LEAST DAYBREAK.  NEW CONVECTIVE DEVELOPMENT IS
   EVIDENT NORTH OF WATERTOWN SD INTO THE REDWOOD FALLS MN...AND
   PROBABLY WILL INTENSIFY THROUGH 10-12Z...IN ENVIRONMENT WITH MOST
   UNSTABLE CAPE INCREASING TO 2000-3000 J/KG.  DEEP LAYER SHEAR ALONG
   FRONTAL ZONE ACROSS THIS REGION IS ALSO BECOMING INCREASINGLY
   SUPPORTIVE OF UPDRAFT ROTATION ROTATION...ENHANCING POTENTIAL FOR
   LARGE HAIL.  COOLER/MORE SATURATED LOW-LEVEL ENVIRONMENT ACROSS
   SOUTHERN MINNESOTA...AS COMPARED TO AREAS ACROSS THE NORTH CENTRAL
   PLAINS...SEEMS LIKELY TO MINIMIZE DAMAGING WIND POTENTIAL.
   
   ..KERR.. 06/21/2007
   
   
   ATTN...WFO...ARX...MPX...FGF...FSD...ABR...
   
   45699764 45859631 45459410 45099343 44669245 44039174
   43539208 43749429 44279637 44849725