LONG PERIOD AVERAGE (LPA)

About: 

• Long Period Average (LPA) is the averages of rainfall received over a 50-year period between 1951 and 2001. This average comes to 89 cm of rainfall. 
  
  
• This is the average rainfall recorded during the months from June to September, calculated during the 50-year period, and is kept as a benchmark while forecasting the quantitative rainfall for the monsoon season every year. 
  
  
• Categories: IMD maintains five rainfall distribution categories on an all-India scale which are – 
  • Normal or Near Normal: When per cent departure of actual rainfall is +/-10% of LPA, that is, between 96-104% of LPA 
    
    
  • Below normal: When departure of actual rainfall is less than 10% of LPA, that is 90-96% of LPA 
    
    
  • Above normal: When actual rainfall is 104-110% of LPA 
    
    
  • Deficient: When departure of actual rainfall is less than 90% of LPA 
    
    
  • Excess: When departure of actual rainfall is more than 110% of LPA