MESOSCALE DISCUSSION 0558
   NWS STORM PREDICTION CENTER NORMAN OK
   0923 AM CDT SAT APR 25 2009
   
   AREAS AFFECTED...LOWER MI
   
   CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 
   
   VALID 251423Z - 251630Z
   
   RADAR COMPOSITES/VISIBLE SATELLITE IMAGERY SHOW A WELL-DEFINED
   MESOSCALE CONVECTIVE VORTICITY /MCV/ CENTER MOVING ACROSS CENTRAL
   LAKE MI.  THIS FEATURE SHOULD TRANSLATE ACROSS LOWER MI THROUGH THE
   AFTERNOON...JUST SOUTH OF A SYNOPTIC FRONT SITUATED ACROSS NORTHERN
   PARTS OF THE STATE. 
   
   THUNDERSTORM LINE SEGMENTS HAVE BEGUN TO INTENSIFY ALONG EASTERN
   QUADRANTS OF THE MCV.  ONE SUCH SEGMENT WAS BEGINNING TO WEAKEN
   ACROSS AREAS FROM GAYLORD EAST AS IT ENTERS A ZONE OF LOWER
   INSTABILITY.  HOWEVER...RECENTLY...ANOTHER BAND HAS INTENSIFIED WEST
   OF OCEANA AND MUSKEGON COUNTIES OVER THE LAKE.  DOWNSTREAM AIR MASS
   WILL HEAT WITH MID-50S SURFACE DEW POINTS MAINTAINED ON STRONG
   LOW-LEVEL SOUTHWEST WINDS.  THUS...THESE STORMS MAY BE MAINTAINED AS
   THEY MOVE INTO CENTRAL LOWER MI.
   
   LARGELY UNIDIRECTIONAL FLOW REGIME NOTED ON AREA VAD WIND PROFILES
   SUGGEST THAT SMALL SCALE BOWS MAY EVOLVE.  AS THE BOUNDARY LAYER
   CONTINUES TO HEAT...PROBABILITIES FOR SURFACE-BASED
   UPDRAFT/DOWNDRAFTS WILL INCREASE AND DAMAGING WIND POTENTIAL MAY
   INCREASE ALONG WITH LARGE HAIL RISKS.  
   
   THE REGION WILL BE MONITORED FOR A POSSIBLE SEVERE THUNDERSTORM
   WATCH.
   
   ..RACY.. 04/25/2009
   
   
   ATTN...WFO...DTX...APX...GRR...
   
   LAT...LON   45388362 43088255 42378477 42768629 43708640 44718486
               45388362