MESOSCALE DISCUSSION 1738
   NWS STORM PREDICTION CENTER NORMAN OK
   0549 PM CDT SUN AUG 12 2007
   
   AREAS AFFECTED...WRN INTO CNTRL IA
   
   CONCERNING...SEVERE THUNDERSTORM WATCH 589...
   
   VALID 122249Z - 130015Z
   
   THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 589
   CONTINUES.
   
   THROUGH 00Z...GREATEST POTENTIAL FOR DAMAGING WINDS WILL EXIST FROM 
   A SHELBY TO MILLS COUNTY IA LINE EWD TO A DALLAS TO UNION COUNTY IA
   LINE.
   
   A MATURE BOW ECHO AS EVOLVED OVER THE PAST HOUR OR SO WITH THE
   LEADING EDGE OF SYSTEM EXTENDING FROM WRN SHELBY COUNTY IA TO ERN
   CASS COUNTY NEB AS OF 2240Z.  THE SYSTEM MOTION HAD ACCELERATED TO
   40-45 KT.  AMBIENT AIR MASS ACROSS SRN IA REMAINS HOT AND EXTREMELY
   MOIST THIS EVENING WITH MLCAPES OF 4000-5000 J/KG.  PRIMARY COLD
   POOL SURGE THUS FAR HAS OCCURRED FROM DODGE AND WASHINGTON COUNTIES
   IN E-CNTRL NEB EWD THROUGH HARRISON AND SHELBY COUNTIES INTO IA. 
   EXTRAPOLATION OF THIS PORTION OF MCS TAKES IT INTO DALLAS COUNTY IA
   BY 00Z.
   
   GIVEN THE LARGE CONVECTIVE MASS TRAILING SWD ALONG THE MO RIVER...AN
   ADDITIONAL COLD POOL SURGE IS ALSO POSSIBLE ACROSS SWRN IA WHERE AIR
   MASS REMAINS EXTREMELY UNSTABLE.  WIND GUSTS TO 50-60 KT WILL BE
   POSSIBLE WITHIN THESE BOWING PORTIONS OF THE MCS.
   
   ..MEAD.. 08/12/2007
   
   
   ATTN...WFO...DMX...OAX...
   
   41689545 41789512 41849418 41749383 41209372 40709422
   40619494 40689536 40879570