LONG RANGE FORECAST (LRF) FOR 2022

• 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.
• While forecasting a ‘normal’ southwest monsoonfor this year, IMD also revised downwards the definition of what constitutes average rainfall.
• Every year, the IMD issues a two-stage forecast: the first one in April and the second one in the last week of May, which is a more detailed forecast and also illustrates how the monsoon will spread over the country.

India Meteorological Department (IMD)

• IMD was established in 1875.
• It is an agency of the Ministry of Earth Sciences.
• It is the principal agency responsible for meteorological observations, weather forecasting and seismology.

Key Highlights of the 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.
• A monsoon is considered “normal” when rainfall falls between 96% and 104% of the LPA.
• 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.
• El Nino is a phenomenon associated with a warming of the Central Pacific and drying up of the rains over northwest India, the coming monsoon.
• La Nina events represent periods of below-average sea surface temperatures across the east-central Equatorial Pacific.
• It is indicated by sea-surface temperature decreased by more than 0.9℉ for at least five successive three-month seasons.
• “Normal” to “above Normal” Rainfall:
• 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.

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) averaged over a long period like 30 years, 50 years, etc”.
• The IMD predicts a “normal”, “below normal”, or “above normal” monsoon in relation to a benchmark “Long Period Average” (LPA).
• The IMD has in the past calculated the LPA at 88 cm for the 1961-2010 period, and at 89 cm for the 1951-2000.
• It calculated the LPA at 87 cm for the 1971-2020 period.
• While this quantitative benchmark refers to the average rainfall recorded from June to September for the entire country, the amount of rain that falls every year varies from region to region and from month to month.
• Therefore, along with the countrywide figure, the IMD also maintains LPAs for every meteorological region of the country.
• This number ranges from around 61 cm for the drier Northwest India to more than 143 cm for the wetter East and Northeast India.

SOURCE: THE HINDU,THE ECONOMIC TIMES,MINT