MESOSCALE DISCUSSION 0808
   NWS STORM PREDICTION CENTER NORMAN OK
   0842 PM CDT TUE MAY 12 2009
   
   AREAS AFFECTED...DAKOTAS...WRN MN/NW IA...NE NEBRASKA.
   
   CONCERNING...SEVERE THUNDERSTORM WATCH 289...291...
   
   VALID 130142Z - 130315Z
   
   THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH
   289...291...CONTINUES.
   
   IT IS NOT CERTAIN THAT A NEW WW WILL BE NEEDED AS ACTIVITY SPREADS
   TOWARD THE EASTERN EDGE OF WWS NEXT COUPLE OF HOURS. 
   
   INITIAL AREA OF STRONGER MID/UPPER FORCING FOR UPWARD VERTICAL
   MOTION...NOW SPREADING ACROSS THE CENTRAL DAKOTAS...APPEARS LIKELY
   TO LIFT THROUGH SOUTHEASTERN NORTH DAKOTA/NORTHWESTERN MINNESOTA
   DURING THE 03-06Z TIME FRAME.  AS THIS OCCURS...THE PRE-FRONTAL
   CONVECTIVE BAND IS EXPECTED TO ADVANCE INTO AND ACROSS THE
   DAKOTAS/MINNESOTA BORDER AREA...WHILE TRAILING MORE DISCRETE CELLS
   SHIFT FROM NORTH CENTRAL NEBRASKA/SOUTH CENTRAL SOUTH DAKOTA INTO
   THE MID MISSOURI VALLEY AREA.  WITH THE SURFACE FRONT/CONVECTIVE
   OUTFLOW NOW OVERTAKING THE PRE-FRONTAL LOW-LEVEL THERMAL RIDGE OVER
   THE CENTRAL DAKOTAS...LOW-LEVEL LAPSE RATES SUPPORTIVE OF STRONG
   DAMAGING SURFACE GUSTS ARE BEING STABILIZED.  FARTHER
   EAST...ELEVATED MOISTURE RETURN BENEATH LINGERING STEEP MID-LEVEL
   LAPSE RATES MAY CONTRIBUTE TO SUFFICIENT CAPE TO SUPPORT THE RISK
   FOR VIGOROUS STORMS CAPABLE OF PRODUCING MARGINALLY SEVERE
   HAIL...PARTICULARLY ACROSS EASTERN SOUTH DAKOTA INTO THE MID
   MISSOURI VALLEY.  BUT...OVERALL THE RISK FOR SEVERE STORMS SEEMS
   LIKELY TO BECOME INCREASINGLY NEGLIGIBLE LATE THIS EVENING.
   
   ..KERR.. 05/13/2009
   
   
   ATTN...WFO...MPX...FGF...FSD...OAX...ABR...BIS...LBF...UNR...
   
   LAT...LON   49659759 49439658 48909599 48099590 47249598 46229571
               45239570 44169556 42899659 42209811 41939963 42420069
               43040046 43689937 44229886 45179872 46389885 47389920
               48199939 48929911 49659759