India to receive normal monsoon

India to receive normal monsoon

News: Recently, the India Meteorological Department (IMD) released its first Long Range Forecast (LRF) for 2022 which says that the country is likely to receive a normal monsoon for the fourth consecutive year.

Highlights of Forecast:
• India would get 99% of the Long Period Average (LPA) rainfall — changed from 89 cm to 88 cm in 2018, and in the periodic update in 2022, again revised to 87 cm.
• The IMD does not expect an El Nino but currently La Nina conditions are prevailing over the equatorial Pacific which will continue during the monsoon.
• Current indications suggest “normal” to “above normal” rainfall in the northern parts of peninsular India, central India and the Himalayan foothills.
• Many parts of northeast India and southern parts of South India are expected to see a subdued monsoon.

How is it predicted?
The IMD predicts a ‘normal’, ‘below normal’, or ‘above normal’ monsoon in relation to a benchmark ‘long period average’ (LPA)
• According to the IMD, the ‘LPA of rainfall is the rainfall recorded over a particular region for a given interval (like month or season) average over a long period like 30 years, 50 years, etc’.

Need for LPA?
• An LPA is needed to smooth out trends so that a reasonably accurate prediction can be made because the IMD records rainfall data at more than 2,400 locations and 3,500 rain-gauge stations.
• A 50-year LPA covers for large variations in either direction caused by freak years of unusually high or low rainfall (as a result of events such as El Nino or La Nina), as well as for the periodic drought years and the increasingly common extreme weather events caused by climate change.

What is the range of a Normal Monsoon?
• The LPA of the season rainfall over the country as a whole for the period 1971-2020 is 87 cm.
• The IMD maintains five rainfall distribution categories on an all-India scale. These are:
o Normal or Near Normal: When the percentage departure of actual rainfall is +/-10% of LPA, that is, between 96-104% of LPA
o Below Normal: When departure of actual rainfall is less than 10% of LPA, that is 90-96% of LPA
o Above normal: When actual rainfall is 104-110% of LPA
o Deficient: When departure of actual rainfall is less than 90% of LPA
o Excess: When the departure of actual rainfall is more than 110% of LPA