MESOSCALE DISCUSSION 1119
   NWS STORM PREDICTION CENTER NORMAN OK
   0925 PM CDT MON JUN 06 2011
   
   AREAS AFFECTED...SOUTH-CENTRAL/EAST-CENTRAL MT
   
   CONCERNING...TORNADO WATCH 435...
   
   VALID 070225Z - 070400Z
   
   THE SEVERE WEATHER THREAT FOR TORNADO WATCH 435 CONTINUES.
   
   TORNADO WATCH 435 CONTINUES UNTIL 07Z FOR PORTIONS OF
   SOUTH-CENTRAL/EAST-CENTRAL MT. THREAT FOR LARGE HAIL AND A TORNADO
   OR TWO CONTINUES...WHILE THE DAMAGING WIND THREAT MAY ALSO INCREASE
   THIS EVENING. AN ADDITIONAL WATCH COULD BE NEEDED FOR PORTIONS OF
   EASTERN MT LATER THIS EVENING.
   
   AROUND 35-40 MILES WEST-NORTHWEST OF THE BILLINGS AREA...NARROWLY
   SPACED SUPERCELLS CONTINUE TO DEVELOP/SPREAD NORTH-NORTHEASTWARD
   EARLY THIS EVENING...WITH RIGHT MOVING SUPERCELLS/SPLITS EXHIBITING
   MORE OF AN EASTERLY MOTION. THESE STORMS ARE OCCURRING WITH A LOW
   LEVEL MOIST/INSTABILITY AXIS TO THE NORTH OF A SURFACE FRONT AND
   DEEPENING SURFACE LOW IN VICINITY OF THE BIG HORN BASIN. A
   RELATIVELY MOIST ENVIRONMENT AND AMPLE LOW LEVEL SHEAR...WITH 0-1 KM
   SRH ESTIMATED TO BE IN EXCESS OF 300 M2/S2 PER THE BILLINGS WSR-88D
   VWP...WILL CONTINUE A TORNADO THREAT /ESPECIALLY IN THE SHORT TERM/
   IN ADDITION TO LARGE HAIL. WITH TIME...GIVEN APPRECIABLY INCREASING
   FORCING FOR ASCENT/VERTICAL SHEAR ATTENDANT TO THE APPROACH POTENT
   UPPER TROUGH...AND A DESTABILIZING AIRMASS ACROSS EASTERN MT /AT
   LEAST IN AN ELEVATED SENSE/...STORMS MAY ULTIMATELY GROW UPSCALE
   THROUGH MID/LATE EVENING WITH A DAMAGING WIND THREAT INCREASING IN
   ADDITION TO CONTINUED BOUTS OF LARGE HAIL.
   
   ..GUYER.. 06/07/2011
   
   
   ATTN...WFO...BYZ...GGW...TFX...
   
   LAT...LON   45260908 45721014 47531036 47660802 47240629 45780604
               45130676 45260908