MESOSCALE DISCUSSION 1901
   NWS STORM PREDICTION CENTER NORMAN OK
   0143 AM CDT MON AUG 27 2007
   
   AREAS AFFECTED...E CNTRL/SE MN...WRN WI...NE IA
   
   CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY 
   
   VALID 270643Z - 270815Z
   
   THE NEED FOR A WW IS NOT CURRENTLY ANTICIPATED...BUT TRENDS ARE
   BEING MONITORED FOR THE POSSIBILITY OF AN INCREASING SEVERE THREAT.
   
   INITIATION OF NEW CONVECTIVE DEVELOPMENT IS UNDERWAY...IN A NORTH/
   SOUTH BAND EXTENDING NEAR/WEST OF MINNEAPOLIS THROUGH THE MASON CITY
   IA AREA.  THIS APPEARS TO BE IN RESPONSE TO LOWER/MID TROPOSPHERIC
   WARM ADVECTION...TO THE SOUTH OF A SHORT WAVE IMPULSE LIFTING INTO
   WESTERN ONTARIO...WITHIN THE STRONGER BELT OF POLAR WESTERLIES.  AS
   MID-LEVEL SHORT WAVE RIDGING BUILDS INTO THE NORTH PLAINS AND UPPER
   MISSISSIPPI VALLEY...THE STRONGER FORCING...AND ASSOCIATED
   THUNDERSTORM ACTIVITY...IS EXPECTED TO SHIFT EASTWARD THROUGH MUCH
   OF WESTERN/CENTRAL WISCONSIN BY 12Z. 
   
   RUC GUIDANCE INDICATES THAT STORMS ARE PROBABLY HIGH BASED...IN A
   VERY MOIST AIR MASS ABOVE A NEAR SURFACE INVERSION LAYER.  LEVELS OF
   FREE CONVECTION ARE LIKELY ABOVE 700 MB...BUT LARGE CAPE ON THE
   ORDER OF 2000 TO 3000 J/KG IS SUPPORTIVE OF VIGOROUS UPDRAFTS.  THIS
   COULD BE SUFFICIENT TO SUPPORT SOME MARGINALLY SEVERE HAIL...
   DESPITE WEAK CLOUD BEARING LAYER SHEAR.  OTHERWISE...AT LEAST BRIEF
   LOCALLY HEAVY RAINFALL AND FREQUENT CLOUD TO GROUND LIGHTNING
   STRIKES APPEAR POSSIBLE AS STORMS INTENSIFY BETWEEN NOW AND
   DAYBREAK.
   
   ..KERR.. 08/27/2007
   
   
   ATTN...WFO...GRB...MKX...DVN...DLH...ARX...MPX...DMX...
   
   45279364 45959293 46359117 45998965 44758932 43198958
   42599042 42299184 42869292 43509308 44209340 44659357