MESOSCALE DISCUSSION 1840
   NWS STORM PREDICTION CENTER NORMAN OK
   0828 PM CDT TUE AUG 21 2007
   
   AREAS AFFECTED...PARTS OF NW KS...SRN NEB
   
   CONCERNING...SEVERE THUNDERSTORM WATCH 632...
   
   VALID 220128Z - 220300Z
   
   THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 632
   CONTINUES.
   
   THE SEVERE THREAT HAS DIMINISHED SOME...BUT COULD INCREASE ONCE
   AGAIN LATER THIS EVENING.  A NEW WW ACROSS PARTS OF SOUTHERN
   NEBRASKA...PERHAPS PARTS OF NORTHERN KANSAS COULD BE REQUIRED. 
   
   RADIATIONAL SURFACE COOLING IS NOW WELL UNDERWAY ACROSS THE CENTRAL
   PLAINS...AND CONSIDERABLE COOLING HAS ALREADY OCCURRED ASSOCIATED
   WITH OUTFLOWS GENERATED BY CONVECTIVE DEVELOPMENT NEAR THE DRY LINE
   EXTENDING TO THE WEST OF KEARNEY NEB/GOODLAND KS.  THIS HAS
   CONTRIBUTED TO WEAKENING TRENDS TO STORMS DURING THE PAST HOUR OR
   SO...WHICH MAY GENERALLY CONTINUE INTO THE 02-04Z TIME FRAME. 
   HOWEVER...NOCTURNAL STRENGTHENING OF THE LOW-LEVEL JET ABOVE THE
   DECOUPLING BOUNDARY LAYER WILL CONTRIBUTE TO STRENGTHENING LOWER/MID
   TROPOSPHERIC WARM ADVECTION...WHICH MAY MAINTAIN SCATTERED
   CONVECTIVE DEVELOPMENT IN A MOIST AND HIGH CAPE ENVIRONMENT. 
   BENEATH A FAVORABLY DIFLUENT/DIVERGENT UPPER FLOW REGIME ACROSS THE
   CENTRAL PLAINS...POTENTIAL EXISTS FOR RENEWED CONVECTIVE GROWTH AND
   POSSIBLE EXPANDING CLUSTER OF STORMS TOWARD THE 06Z TIME FRAME. 
   THIS SEEMS MOST PROBABLE ACROSS THE KEARNEY/GRAND ISLAND/HASTING
   AREAS...WHERE THE NOSE OF THE 35-40 KT LOW-LEVEL JET MAY FOCUS
   LOW-LEVEL CONVERGENCE.  IF THIS OCCURS...MODERATE DEEP LAYER SHEAR
   AS FAR SOUTH AS THE NEBRASKA/KANSAS BORDER WILL BE SUFFICIENT FOR
   UPDRAFT ROTATION AND ENHANCED RISK FOR HAIL...IN ADDITION TO LOCALLY
   HEAVY RAINFALL... IN SLOW MOVING/TRAINING CELLS.
   
   ..KERR.. 08/22/2007
   
   
   ATTN...WFO...OAX...TOP...ICT...GID...LBF...DDC...GLD...
   
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