MESOSCALE DISCUSSION 1705
   NWS STORM PREDICTION CENTER NORMAN OK
   0933 PM CDT THU AUG 09 2007
   
   AREAS AFFECTED...NORTHEAST/EAST CENTRAL NEB INTO WESTERN
   IA/SOUTHEAST SD
   
   CONCERNING...SEVERE THUNDERSTORM WATCH 576...577...
   
   VALID 100233Z - 100400Z
   
   THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH
   576...577...CONTINUES.
   
   VALID PORTIONS OF SEVERE WATCHES 576/577 CONTINUES...WITH PRIMARY
   RISK OF DAMAGING WINDS AND LARGE HAIL. CLOSELY MONITORING FOR THE
   POSSIBILITY OF A NEW SEVERE THUNDERSTORM WATCH OVER THE NEXT HOUR OR
   SO ACROSS EAST CENTRAL NEB AND PERHAPS FAR WESTERN IA.
   
   QUASI-LINEAR MCS WITH HISTORY OF DAMAGING WINDS/LARGE HAIL CONTINUES
   TO ADVANCE SOUTHEASTWARD AT AROUND 30 KT...ROUGHLY CENTERED BETWEEN
   THE O'NEILL AND NORFOLK AREAS AS OF 0230Z. ALTHOUGH SHORT-TERM
   UNCERTAINTY EXISTS REGARDING THE EAST-SOUTHEAST EXTENT OF SEVERE
   POTENTIAL WITH THE EXISTING MCS...SEVERAL FACTORS SUGGEST A SEVERE
   THREAT COULD EXTEND/SPREAD DOWNSTREAM TOWARD THE MISSOURI RIVER.
   DOWNSTREAM OF THE MCS...00Z OMAHA OBSERVED SOUNDING SAMPLED A VERY
   MOIST/UNSTABLE AIRMASS...WITH A STEEP LAPSE RATE ENVIRONMENT AND
   MLCAPE AROUND 3800 J/KG...IN ADDITION TO AMPLE DRY AIR
   ALOFT...FAVORABLE FOR STRONG DOWNDRAFTS/DAMAGING WINDS. ALTHOUGH MCS
   WILL SPREAD EAST OF THE LOW LEVEL JET AXIS AND GRADUAL BOUNDARY
   LAYER COOLING IS OCCURRING...WELL-ORGANIZED NATURE OF THE MCS/COLD
   POOL AND LOW LEVEL EAST-SOUTHEASTERLY LOW LEVEL FLOW AMIDST A VERY
   UNSTABLE AIRMASS FAVORS FORWARD PROPAGATION INTO EAST CENTRAL NEB
   AND PERHAPS WESTERN IA...POTENTIALLY INCLUDING THE OMAHA METRO AREA.
   
   ..GUYER.. 08/10/2007
   
   
   ATTN...WFO...DMX...FSD...OAX...GID...LBF...
   
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