MESOSCALE DISCUSSION 0859
   NWS STORM PREDICTION CENTER NORMAN OK
   0226 PM CDT TUE MAY 22 2007
   
   AREAS AFFECTED...CNTRL/SCNTRL NEB...WRN KS
   
   CONCERNING...SEVERE POTENTIAL...TORNADO WATCH LIKELY 
   
   VALID 221926Z - 222130Z
   
   TSTMS SHOULD INITIATE BETWEEN 21-22Z ACROSS PORTIONS OF SCNTRL NEB
   AND WRN KS WITH AN INCREASING THREAT FOR LARGE HAIL...TORNADOES AND
   DAMAGING WIND GUSTS.  A TORNADO WATCH WILL BE REQUIRED FOR PARTS OF
   THE REGION.
   
   LATEST PROFILER/VWP PLOTS SHOW AN AREA OF INCREASING DIVERGENCE
   ALOFT AS H5/H25 JET TURNS NWD ACROSS ERN CO INTO NEB AND A SECOND
   BRANCH PEELS MORE ENEWD ACROSS OK AND CNTRL KS.  AT THE
   SFC...LEE-LOW OVER EXTREME SWRN KS AT 18Z IS EXPECTED TO DEVELOP
   SLOWLY NEWD ALONG AN INITIAL SURGE OF MORE DENSE/COLD AIR INTO NWRN
   KS BY LATE AFTN.  AHEAD OF THIS FEATURE...LOW-LEVEL FLOW HAS BACKED
   TO SSELY WITH INCREASING CONVERGENCE NOTED FROM NEAR LEXINGTON NEB
   SWWD TO NEAR/NW OF GARDEN CITY KS. VSBL SATL SHOWS INCREASING SFC
   BASED CUMULUS ALONG THIS ZONE AND CONTINUED HEATING SHOULD ERASE
   INHIBITION SUFFICIENTLY FOR INITIATION BY 22Z.  
   
   VERTICAL SHEAR IS MORE SUBSTANTIAL ACROSS SRN NEB AND KS GIVEN
   GREATER DEGREE OF CROSS-OVER BETWEEN LOW- AND MID-LEVEL FLOW
   REGIMES.  THUS...THE SUPERCELL THREAT WILL LIKELY BE HIGHER THAN AT
   POINTS FARTHER TO THE NORTH.  STEEP LAPSE RATES ALOFT AND MAGNITUDE
   OF SHEAR SUGGEST LARGE HAIL...SOME LARGER THAN 2 INCHES IN
   DIAMETER...WILL BE LIKELY.  MOREOVER...0-1KM SHEAR...PARTICULARLY
   VCNTY THE SFC LOW TRACK...WILL BE MORE THAN ENOUGH FOR TORNADOES.  
   
   ACTIVITY WILL SLOWLY PROGRESS EWD TOWARD CNTRL KS AND SCNTRL NEB
   TOWARD THE US HIGHWAY 281 CORRIDOR LATER THIS EVENING.
   
   ..RACY.. 05/22/2007
   
   
   ATTN...WFO...GID...LBF...DDC...GLD...
   
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