MESOSCALE DISCUSSION 1589
   NWS STORM PREDICTION CENTER NORMAN OK
   0209 AM CDT TUE JUL 12 2011
   
   AREAS AFFECTED...PORTIONS CENTRAL/ERN NEB...EXTREME SERN SD...WRN
   IA.
   
   CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 
   
   VALID 120709Z - 120815Z
   
   TSTM TRENDS WILL BE MONITORED FOR POSSIBLE WW.
   
   BOW ECHO THAT EVOLVED FROM EARLIER CONVECTION OVER SWRN NEB AND NERN
   CO IS MOVING NEWD 35-40 KT ACROSS ERN PORTIONS NEB SANDHILLS. 
   CONVECTIVE TRENDS HAVE REMAINED QUASI-STEADY WITH THIS COMPLEX ON
   END...WEAKENING ON S END.  ACTIVITY HAS YIELDED GUSTS BELOW SVR
   LIMITS AT STATIONS IT HAS CROSSED...EXCEPT FOR 59-KT NON-TSTM GUST
   506Z AT MCK IN PORTION OF GUST FRONT WELL-REMOVED FROM CONVECTION. 
   CONVECTION MAY TURN MORE EWD OVER CENTRAL-ERN NEB INTO MORE
   FAVORABLE AIR MASS...IN WHICH CASE SVR THREAT MAY DEVELOP ACROSS MO
   RIVER VALLEY INTO WRN IA.  WW MAY BE REQUIRED IF TRENDS
   STRENGTHEN...PROSPECTS FOR WHICH INVOLVE MIXED SIGNALS ATTM.
   
   SFC MESOANALYSIS SHOWS QUASISTATIONARY BAROCLINIC ZONE...RELATED TO
   AND REINFORCED BY OUTFLOW FROM CONVECTION JUST TO ITS N...EXTENDING
   FROM GARFIELD COUNTY NEB ENEWD NEAR OFK-SUX-SLB LINE. SHARP DROP IN
   THETAE AND INCREASE IN BOUNDARY-LAYER STABILITY N OF THIS BOUNDARY
   INDICATES IT WILL SERVE AS NRN BOUND FOR MOST ROBUST GUST POTENTIAL.
    FARTHER S...MOIST AXIS IS ANALYZED NEAR WARM FRONT OVER MO...THEN
   SPLITTING NNWWD FROM FRONTAL ZONE OVER NERN KS TO S-CENTRAL
   NEB...WITH LOW-MID 70S F DEW POINTS COMMON.  MLCAPE 2000-2500 J/KG
   IS EVIDENT NEAR THAT MOIST AXIS...DIMINISHING NWD TOWARD
   BOUNDARY...WITH ABOUT 100-150 J/KG MLCINH BASED ON MODIFIED RAOBS
   AND RUC SOUNDINGS.  BUOYANCY THEREFORE WILL BE FAVORABLE FOR ANY
   PARCELS THAT CAN BE FORCED TO LFC ALONG LEADING EDGE OF COLD POOL. 
   HOWEVER...BOTH UPDRAFTS AND DOWNDRAFTS MAY BE MUTED FOR PARCELS NEAR
   SFC DUE TO REINFORCEMENT OF THAT CINH BY CONTINUED/GRADUAL DIABATIC
   COOLING.  STORM-RELATIVE INFLOW MAY REMAIN ENHANCED BY BACKING OF
   SFC-850 MB WINDS AHEAD OF MCS.  FCST FORWARD-PROPAGATIONAL MCS
   MOTION VECTORS SUGGEST EWD TURN WITH TIME...WHICH IS REASONABLE
   GIVEN ANTICYCLONIC CURVATURE OF AMBIENT MID-UPPER
   WINDS...STRENGTHENING CINH WITH NWD EXTENT ACROSS BOUNDARY...AND
   PRESENCE OF MOST FAVORABLE INSTABILITY S OF CURRENTLY EXTRAPOLATED
   TRACK.  ATTM...HOWEVER...ONE COLD POOL EFFECTIVELY IS PENETRATING
   ANOTHER TO A GREAT EXTENT...LIMITING NEAR-TERM SVR THREAT.
   
   ..EDWARDS.. 07/12/2011
   
   
   ATTN...WFO...DMX...FSD...OAX...GID...LBF...
   
   LAT...LON   41289919 41769927 42519956 42929787 43189592 42889486
               41079482 41009606 41079724 41289919