IMD forecasts ‘normal’ monsoon, no El Nino

Published
15th Apr, 2022

Context

India Meteorological Department (IMD) forecasted a ‘normal’ southwest monsoon for 2022. Meanwhile, it downgraded the definition of what is an average rainfall.

About

IMD’s Monsoon Forecast for 2022

IMD updated long period average rainfall to 87 cm. India would get 99% of the long period average (LPA) rainfall.
Last change in long period average (LPA) rainfall was in 2018 where it was changed from 89 cm to 88 cm, and now is again revised to 87 cm.
A monsoon is considered “normal” when rainfall falls between 96% and 104% of the LPA.
There will be a weak El Nino indicating a negligible adverse impact on Indian monsoon while there will be a favourable La Nina phenomenon.

India Meteorological Department

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

Long Period Average

LPA is the averages of rainfall received over a 50-year period between 1951 and 2001 which comes to 89 cm of rainfall.
It recorded during the months from June to September.
It is set as a benchmark while forecasting the quantitative rainfall for the monsoon season every year.
Following are the five rainfall distribution categories on an all-India scale maintained by IMD:
- Excess:When departure of actual rainfall is more than 110% of LPA.
- Above Normal:When actual rainfall is 104-110% of LPA.
- Normal or Near Normal:When per cent departure of actual rainfall is +/-10% of LPA, i.e., between 96-104% of LPA.
- Below Normal:When departure of actual rainfall is less than 10% of LPA, e., 90-96% of LPA.
- Deficient:When departure of actual rainfall is less than 90% of LPA.

About El Nino

El Nino (Spanish for Christ Child) is the occasional development of warm ocean surface waters along the coast of Ecuador and Peru.
The El Nino normally occurs around Christmas, roughly every 2 to 7 years and lasts usually for a few weeks to a few months.
El Nino and the Indian Monsoon rains are inversely related. It results in hotter than usual summers and drought-like conditions.
About La Nina
La Nina is a climate pattern that describes the cooling of surface ocean water along the tropical west coast of South America.
It is considered as the counterpart of El Nino, and its impacts tend to be opposite those of El Niño.
Together, they form the "cold" (La Nina) and "warm" (El Nino) phases of the El Nino-Southern Oscillation (ENSO).