SPC MESOSCALE DISCUSSION 1138 FOR SRN AND CNTRL NEB
CONCERNING...SEVERE THUNDERSTORM POTENTIAL...

VALID 120542Z - 120900Z

CURRENT TRENDS SUGGEST SEVERE THUNDERSTORM WATCH MAY BE NEEDED
ACROSS AREA WITHIN THE NEXT HOUR.

LOW-LEVEL CONVERGENCE/WARM ADVECTION IS BECOMING FOCUSED ACROSS
SOUTHWEST NEBRASKA...ON NOSE OF STRENGTHENING SOUTHERN HIGH PLAINS
LOW-LEVEL JET.   THIS IS SUPPORTING ONGOING CONVECTIVE DEVELOPMENT
WEST/NORTHWEST OF IMPERIAL...WHICH APPEARS LIKELY TO CONTINUE
INCREASING IN COVERAGE AND ORGANIZING THROUGH THE OVERNIGHT HOURS. 

WEAK SHORT WAVE TROUGH MIGRATING NORTHEASTWARD FROM THE COLORADO
ROCKIES WILL CONTRIBUTE TO STRENGTHENING UPPER DIVERGENCE ACROSS
SOUTHERN NEBRASKA DURING THE NEXT SEVERAL HOURS...SUPPORTING
EVOLUTION OF SMALL CONVECTIVE SYSTEM...PROGRESSING TOWARD THE GRAND
ISLAND AREA THROUGH 12Z.  ELEVATED MOIST LAYER AND STEEP MID-LEVEL
LAPSE RATES WILL PROVIDE FAVORABLE THERMODYNAMIC ENVIRONMENT FOR
LARGE HAIL...ESPECIALLY WITH INITIAL ACTIVITY.  GIVEN PRESENCE OF
DRY MID-LEVEL AIR...BOUNDARY LAYER NORTH OF SURFACE FRONT MAY BE
SUFFICIENTLY WARM/MOIST TO SUPPORT THREAT FOR ORGANIZED SURFACE
COLD POOL AND ASSOCIATED DAMAGING WIND THREAT.

..KERR.. 06/12/01