SPC MESOSCALE DISCUSSION 1619 FOR N CNTRL/NERN MT
   CONCERNING...TORNADO WATCH 580...
   
   VALID 062323Z - 070100Z
   
   LARGE SUPERCELL OVER TREASURE COUNTY MONTANA MOVING 180/20. 
   EXTRAPOLATION HAS STORM MOVING INTO TORNADO WATCH AROUND 0100Z
   ALONG ROSEBUD/GARFIELD COUNTY LINE.  RADAR DATA FROM GGW WSR-88D
   AND LATEST SURFACE DATA INDICATES A NORTH-SOUTH TROUGH AXIS
   EXTENDING FROM SUPERCELL NORTHWARD TO JUST EAST OF GGW. 
   THUS...STORMS IN SOUTHEAST MONTANA WILL LIKELY TRACK NORTH-
   NORTHEASTWARD ALONG THIS BOUNDARY DURING THE EVENING.  
   
   OTHER SUPERCELL OVER FERGUS COUNTY MONTANA WILL BE TRACKING
   NORTHEASTWARD THROUGH INSTABILITY MAXIMUM AND TOWARD BEST CURRENT
   COMBINATION OF DEEP LAYER SHEAR/INSTABILITY OVER PHILLIPS/VALLEY
   COUNTY AREA.  MLLCL HEIGHTS ARE PROGRESSIVELY LOW FROM SOUTH TO
   NORTH ACROSS MONTANA CURRENTLY.  THUS...TORNADO POTENTIAL SHOULD
   INCREASE AS SUPERCELLS ENCOUNTER MIDDLE 60S DEWPOINTS AND INTERACT
   WITH SURFACE BOUNDARY.  
   
   ..CRAVEN.. 08/06/02