MESOSCALE DISCUSSION 1835
   NWS STORM PREDICTION CENTER NORMAN OK
   0630 AM CDT SUN AUG 09 2009
   
   AREAS AFFECTED...PORTIONS CENTRAL/ERN NEB...WRN THROUGH NERN IA.
   
   CONCERNING...SEVERE THUNDERSTORM WATCH 680...
   
   VALID 091130Z - 091330Z
   
   THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 680
   CONTINUES.
   
   ANOTHER WW WILL BE NEEDED FARTHER DOWNSHEAR ACROSS MORE OF IA...AS
   INCREASINGLY WELL-ORGANIZED AREA OF STG-SVR TSTMS ENCOUNTERS
   PROGRESSIVELY GREATER BUOYANCY ROOTED CLOSER TO SFC.
   
   A COUPLE ESTIMATES OF 1/75 INCH HAIL HAVE BEEN RECEIVED FROM NANCE
   COUNTY NEB DURING PAST HOUR.  THIS ACTIVITY SHOULD MOVE ENEWD INTO
   IA AROUND 1230Z...PRECEDED BY INCREASINGLY WELL-DEFINED
   WARM-ADVECTION WING OF TSTMS MOVING OVER SUX AREA.  LARGE HAIL
   THREAT SHOULD CONTINUE WITH THIS COMPLEX...AND PERHAPS TRAILING TSTM
   CLUSTER 50-80 NM FARTHER WSW...AS EACH PROCEEDS ENEWD ACROSS MO
   VALLEY.  WIND DAMAGE POTENTIAL ALSO MAY DEVELOP AS TWO PRIMARY
   PROCESSES TAKE PLACE:
   
   1. LAGRANGIAN -- CONVECTION OBLIQUELY APCHS SFC COLD FRONT...AND IN
   DOING SO...MOVES OVER PROGRESSIVELY HIGHER AMBIENT THETAE AND ALSO
   SHALLOWER/POSTFRONTAL LAYER OF STATIC STABILITY ALONG STORM TRACK. 
   FAVORABLY BUOYANT/ELEVATED INFLOW LAYER BECOMES WIDER IN HORIZONTAL
   EXTENT WITH HIGHER MOISTURE CONTENT ALONG PROJECTED TRACK INTO
   IA...SUPPORTING POTENTIAL FOR FURTHER MCS EXPANSION/INTENSIFICATION.
   
   2. EULERIAN -- IR IMAGERY INDICATES MINIMAL CLOUD IMPEDIMENT TO
   DIABATIC HEATING OVER CENTRAL/ERN IA AFTER SUNRISE...WHICH WILL
   BEGIN TO ERODE MLCINH...INCREASE MLCAPE AND THEREBY BOOST POTENTIAL
   FOR SVR GUSTS AT SFC FROM STORMS ENTERING THIS TEMPORALLY
   DESTABILIZING AIR MASS.
   
   45-50 KT EFFECTIVE SHEAR MAGNITUDES SHOULD CONTINUE ALONG PROJECTED
   MCS PATH...WHICH CORRESPONDS CLOSELY TO GRADIENT OF CAPE LOCATED N
   OF NEARLY PARALLEL LOW LEVEL THETAE AXIS.
   
   ..EDWARDS.. 08/09/2009
   
   
   ATTN...WFO...DVN...ARX...DMX...FSD...OAX...GID...
   
   LAT...LON   41289877 42049746 42419651 42739514 43299293 42979195
               41849212 40819723 40819923 41289877