SPC MESOSCALE DISCUSSION 0670 FOR ERN NE/NE KS/WRN IA/NW MO
   CONCERNING...TORNADO WATCH 226...229...230...
   
   VALID 060007Z - 060200Z
   
   CONVECTIVE TRENDS CONTINUE TO BE MONITORED FOR POSSIBILITY OF NEW
   WWS.
   
   SUBTROPICAL SPEED MAXIMUM TOPPING SOUTHERN PLAINS UPPER RIDGE AND
   NORTHERN BRANCH SHORT WAVE TROUGH MIGRATING OUT OF THE NORTHERN
   ROCKIES INTO THE NORTHERN PLAINS ARE COMBINING TO FOCUS STRONG
   DIVERGENT UPPER FLOW FIELD ACROSS THE MIDDLE MISSOURI VALLEY.  THIS
   HAS ENHANCED INTENSE CONVECTIVE DEVELOPMENT PAST FEW HOURS IN MOIST
   AND MODERATELY UNSTABLE ENVIRONMENT EAST OF SURFACE TROUGH/DRY LINE
   OVER CENTRAL/EASTERN NEBRASKA AND NORTH CENTRAL/NORTHEAST KANSAS. 
   THUNDERSTORMS HAVE BECOME INCREASINGLY NUMEROUS...BUT ACTIVITY
   REMAINS GENERALLY CELLULAR...AND TO THIS POINT...RATHER UNORGANIZED
   DUE TO LACK OF LOW-LEVEL FOCUS.  DRY AIR EVIDENT IN 06/00Z RAOB
   FROM OMAHA NEB SUGGESTS POTENTIAL FOR SLOW EVOLUTION OF LARGE
   SURFACE COLD POOL DURING THE NEXT FEW HOURS FROM EXTENSIVE ONGOING
   ACTIVITY.  IF THIS OCCURS...GUST FRONT SHOULD SURGE EAST OF THE
   MISSOURI RIVER INTO PARTS OF NORTHWEST MISSOURI AND WESTERN IOWA
   WITH THREAT FOR DAMAGING WIND GUSTS...BENEATH MODERATELY STRONG
   WESTERLY MID-LEVEL FLOW...BEFORE ACTIVITY WEAKENS IN MORE STABLE
   AIR MASS LATER THIS EVENING.
   
   ..KERR.. 05/05/02