SPC MESOSCALE DISCUSSION 1592 FOR MUCH OF WRN AND CENTRAL MT
CONCERNING...SEVERE THUNDERSTORM POTENTIAL...

VALID 202303Z - 210100Z

WE ARE MONITORING PORTIONS OF CENTRAL MT FOR A POSSIBLE SEVERE
THUNDERSTORM WATCH IN THE NEXT FEW HOURS.

LATEST WV IMAGERY INDICATES THAT CONVECTION WAS DEVELOPING OVER WRN
MT/NRN ID IN REGION OF STRONG ASCENT/UPPER LEVEL DIVERGENCE AHEAD
OF APPROACHING PACIFIC JET. DEEP LAYER SHEAR PROFILES REMAIN VERY
FAVORABLE FOR ORGANIZED ROTATING UPDRAFTS. HOWEVER...INSTABILITY
REMAINS VERY MARGINAL WITH LATEST OBJECTIVE ANALYSIS INDICATES LESS
THAN 500 J/KG OF MLCAPE WEST OF A LINE FROM BILLINGS TO LEWISTOWN.
HOWEVER...LOW LEVEL T/TD SPREADS REMAIN RELATIVELY HIGH /NEAR 40
DEG F/ THUS THERE MAY BE SOME POTENTIAL FOR AN ISOLATED DAMAGING
DOWNBURST/MARGINALLY SEVERE HAIL WITH ACTIVITY CURRENTLY OVER WRN
MT. AS CONVECTION MOVES FARTHER EWD...IT WILL ENCOUNTER AN
INCREASINGLY UNSTABLE AIRMASS. THUS WE ARE EXPECTING
INTENSIFICATION/GREATER SEVERE THREAT AS ONGOING CONVECTION
APPROACHES ROUGHLY THE LONGITUDE OF LEWISTOWN AND BILLINGS.

..CROSBIE.. 07/20/01