SPC MESOSCALE DISCUSSION 1580 FOR SD AND ND
CONCERNING...TORNADO WATCH 589 AND SEVERE THUNDERSTORM WATCH 588...

VALID 200235Z - 200430Z

THUNDERSTORM CLUSTER MOVING EWD ALONG ND/SD BORDER NEAR Y22 IS
LIKELY TO COLLIDE WITH NWD MOVING BAND OF THUNDERSTORMS MOVING NWD
FROM SW OF Y26.  CURRENT PROJECTIONS WOULD HAVE THE MERGER TAKING
PLACE IN WESTERN CORSON CO SD ABOUT 03Z WITH THE MERGER CONTINUING
TO TAKE PLACE NEWD INTO SRN MORTON CO ND BY 0430Z.  THERE MAY BE
ENHANCE SEVERE POTENTIAL AS THIS MERGER TAKES PLACE.

..JOHNS.. 07/20/01