NORTH COAST        
            Long Range Forecast      
            Issued July 26, 2010        
     
  LONG RANGE PERIOD  
      July Summer Fall Winter  
  Temperature Trend Equal Chances Equal Chances Equal Chances Below  
  Confidence ** ** ** low  
                       
  Precipitation Trend Equal Chances Equal Chances Above Equal Chances  
  Confidence ** ** low **  
                       
  TEMPERATURES NORMALS 1971-2000  
  temperature max min max min max min max min  
  Eureka   63 53 64 53 57 44 55 43  
  Lakeport   94 54 91 52 63 36 59 35  
  Santa Rosa 82 53 82 53 66 42 62 41  
  Napa   83 55 83 54 66 43 62 41  
                       
  PRECIPITATION NORMALS 1971-2000  
  precipitation inches inches inches inches  
  Eureka   0.19 1.42 14.52 16.97  
  Lakeport   0.07 0.69 11.47 18.68  
  Santa Rosa 0.07 0.70 10.72 16.69  
  Napa   0.05 0.58 9.24 14.37  
  Winter = Jan-Mar, Spring = Apr-Jun, Summer = Jul-Sep, Fall = Oct-Dec  
  Note: Equal chances denotes an equal probability of above, below or a near normal event will occur.  
  (**) means not applicable as a forecast of equal chances does not have a confidence associated with it.  
                       
 
Text Box: DISCUSSION: Climatologically, it will take another couple months of cooler than normal sea surface temperatures over the equatorial Eastern Pacific waters before it can officially be classified a La Nina event. This seems quite likely since a large reservoir of cooler than normal water persists from near the surface to considerable depth along the Equator. In addition, nearly all climatic models show La Nina conditions in place by late summer and project it to last into the winter and probably well beyond. In the near term, climatic models are reluctant to extend unseasonably warm conditions expected over the eastern and central United States to include the Pacific Coast. (hence the equal chances for forecast for August). Further down the road, climatic models are mixed on how strong this La Nina event will become and thus maintain an equal chances prognostication for the state (both for temperatures & precipitation) through the fall and winter. Moderate to strong La Nina events generally leave the wet season with cooler than normal temperatures with the Central and South State left unusually dry. The North State during these La Nina event ends up the transition zone between wet conditions across the Pacific Northwest and the very dry conditions to the south, and thus can end up anywhere from quite wet to quite dry. Cushman