MESOSCALE DISCUSSION 1827
   NWS STORM PREDICTION CENTER NORMAN OK
   0327 PM CDT SAT AUG 08 2009
   
   AREAS AFFECTED...ERN MN INTO WRN WI
   
   CONCERNING...TORNADO WATCH 677...
   
   VALID 082027Z - 082100Z
   
   THE SEVERE WEATHER THREAT FOR TORNADO WATCH 677 CONTINUES.
   
   NEW TORNADO WATCH WILL BE COORDINATED SHORTLY BETWEEN THE SPC AND
   AFFECTED WFOS TO THE EAST OF WW 677.
   
   MID AFTERNOON SURFACE ANALYSIS SHOWED THE LOW HAS REACHED FAR SWRN
   MN...WITH THE WARM FRONT CONTINUING TO RETREAT NWD ACROSS SRN TO
   CENTRAL MN.  STRONG SURFACE HEATING S OF THE WARM FRONT /UPPER 80S
   TO AROUND 90/ WITHIN VERY MOIST AIR MASS /SURFACE DEWPOINTS LOW-MID
   70S/ IS CONTRIBUTING TO VERY STRONG INSTABILITY ACROSS MUCH OF SRN
   MN INTO IA WITH EXTREME INSTABILITY /MLCAPE 4000+ J/KG/ EXTENDING
   NWWD FROM CENTRAL IA INTO SWRN MN.  OBJECTIVE ANALYSES INDICATED THE
   AIR MASS IMMEDIATELY DOWNSTREAM OF THE LEAD STORM WHICH JUST ENTERED
   SWRN MN HAS BECOME UNCAPPED.  THIS SUGGESTS THIS STORM WILL BE
   SURFACE BASED AS IT PROGRESSES NEWD LATE THIS AFTERNOON TOWARD ERN
   EXTENT OF WW 677.  ADDITIONAL SURFACE BASED DEVELOPMENT IS POSSIBLE
   AS STRONG FORCING FOR ASCENT SPREADS EWD IN MN.  VISIBLE SATELLITE
   IMAGERY/REGIONAL RADARS INDICATED STORMS DEVELOPING EWD ALONG THE
   WARM FRONT THROUGH THE SRN TWIN CITIES METRO TO WEST CENTRAL WI. 
   STRONG FORCING ALOFT COMBINED WITH VERY STRONG INSTABILITY AND
   STRONG DEEP LAYER SHEAR WILL FAVOR SUPERCELLS WITH TORNADOES...VERY
   LARGE HAIL AND DAMAGING WINDS.
   
   ..PETERS.. 08/08/2009
   
   
   ATTN...WFO...DLH...ARX...MPX...DMX...FGF...FSD...
   
   LAT...LON   42969771 43949661 44909590 45779572 46389506 46029359
               45679180 45499087 44519055 43789114 43679178 43529421
               42969771