Indian Meteorological Department(IMD) revised Long Period Average Of Rainfall

The IMD or the Indian Meteorological Department, established in 1875 is an agency of the Ministry of Earth Sciences of India. It is the National Meteorological Service Provider of the country and the principal government agency responsible for the meteorological observations, weather forecasting, seismology, and all-weather related services in the country. It provides the country with all the current meteorological observations as well as forecasting of meteorological information. 

What are all the functions of IMD?

• The IMD records data from 3,500 rain-gauge stations at 2,412 locations and gives two Long-Range Forecasts (LRF) yearly with the first one being published in April and the second one being published in the last week of May
• 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 an extended period like 30 years, 50 years, etc”
• This year the LRF says that the country will get a normal monsoon and will receive 99% of the LPA Rainfall (Long Period Average) which has been updated from 89 cm to 88 cm in 2018 and has again been revised to 87 cm in the periodic update of 2022
• Private Weather Forecaster Skymet has started following its detailed official forecast of 2022 that the forecast monsoon in 2022 to be ‘normal’, the first half of the southwest monsoon (June and July) is expected to fare better than the latter half of the season (August and September)

What is the importance of LPA?

• Due to the variations in the rainfall encountered across the different regions in the country and varying monthly in a particular region, An LPA becomes especially important to aid in smoothing out previously recorded trends so that a reasonably accurate prediction can be made
• LPA’s are recorded across 50 years as seen in the LPA for 1951-200 with an 89 cm, and in the 1961-2010 and 1971-2020 LPA with 88 cm and 87 cm respectively, these 50 years long forecast not only allow for the large variations caused by unforeseen events such as El Nino or La Nina but also take into account the forecasted drought years and an ever-increasing number of extreme weather events due to climate change

What are the highlights of the LRF published by IMD in April?

• India will observe a normal monsoon, meaning it will be with (+/-) 5% of the LPA
• The LPA has been updated from 88 cm in 2018 to 87 cm in 2022
• IMD does not expect El Nino to arrive but conditions for La Nina are prevailing over Equatorial Pacific
• The report suggests that “normal” or “above normal” rainfall might be observed in the northern parts of India, central India and the Himalayan foothills
• Parts of the northeastern part of India and the southern parts of South India are expected to receive a subdued monsoon

Conclusion

To reiterate the reason behind the IMD’s revision of the LPA and what it means for you. We need to understand that need for IMD to revise the LPA Annual rainfall is directly correlated to the varying weather conditions which not only change from region to region at different periods, and the IMD provides these revisions according to the Data it collects from its Rain Gauge Stations to help but also from year to year within a particular region or month. It is important to understand that a ‘normal’ monsoon doesn’t automatically guarantee farm prosperity or rural spending. The actual distribution of the average rainfall of 89 in India varies from region to region and it is critical information for farmers to have over the months in which sowing of grains is done, as it help’s India’s farming Industry. IMD’s forecasts play a key role in the policy-making of the government regarding their pre-monsoon preparations and having insight into the variations observed in rainfall helps us to shed light on the effects of climate change and the effect it is having on India’s Rainfall Patterns.