MESOSCALE DISCUSSION 1092 NWS STORM PREDICTION CENTER NORMAN OK 1159 AM CDT THU JUN 07 2012 AREAS AFFECTED...ERN WY AND ADJACENT PORTIONS OF THE NEBRASKA PNHDL/SWRN SOUTH DAKOTA...N CNTRL/NERN CO CONCERNING...SEVERE POTENTIAL...WATCH LIKELY VALID 071659Z - 071830Z PROBABILITY OF WATCH ISSUANCE...80 PERCENT SUMMARY...TIMING IS STILL SOMEWHAT UNCERTAIN...BUT A WW WILL LIKELY BE NEEDED BY 20-21Z...IF NOT BEFORE. DISCUSSION...ISOLATED TO WIDELY SCATTERED STORMS HAVE ALREADY INITIATED OFF THE MEDICINE BOW MOUNTAINS IN RESPONSE TO BOUNDARY LAYER DESTABILIZATION AND OROGRAPHIC FORCING. THIS PROBABLY HAS BEEN AIDED BY FORCING FOR UPWARD VERTICAL MOTION ASSOCIATED WITH LARGER SCALE MID/UPPER TROUGHING LIFTING OUT OF THE EASTERN GREAT BASIN...WHICH IS EXPECTED TO CONTRIBUTE TO ADDITIONAL INCREASING STORM DEVELOPMENT NEAR/NORTH AND EAST OF THE LARAMIE MOUNTAINS BY THE 18-20Z. MODERATELY SHEARED DEEP LAYER MEAN FLOW IS STILL SOUTHERLY...BUT EXPECTED TO VEER WITH TIME WHICH WILL CONTRIBUTE TO EASTWARD PROPAGATION OF STORMS THROUGH THE HIGH PLAINS...WHERE CONVECTIVE INHIBITION WILL CONTINUE TO WEAKEN...AS MIXED LAYER CAPE INCREASES IN EXCESS OF 1500 J/KG. LARGE HAIL APPEARS THE PRIMARY SEVERE THREAT...PARTICULARLY WITH INITIAL ACTIVITY NEAR THE HIGHER TERRAIN. HOWEVER...AS ACTIVITY STRENGTHENS AND DEVELOPS EASTWARD...A FEW SUPERCELLS ARE EXPECTED...ALONG WITH THE RISK FOR LOCALLY DAMAGING WIND GUSTS...PERHAPS AN ISOLATED TORNADO OR TWO. ..KERR/WEISS.. 06/07/2012 ATTN...WFO...UNR...BOU...CYS...RIW...
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