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Above normal rainfall, temperatures in October: IMD
The India Meteorological Department (IMD) on Tuesday forecast that most parts of the country will face above normal rainfall in October, adding that day and night temperatures will likely be above normal.
The India Meteorological Department (IMD) on Tuesday forecast that most parts of the country will face above normal rainfall in October, adding that day and night temperatures will likely be above normal.
The IMD said that October will receive 115% of the long period average. The LPA of rainfall over the country during October, based on data from 1971 to 2020, is 75.4 mm.
The spatial distribution suggests above normal rainfall in most parts of the country during October except few parts of northeast India, northwest India and south peninsula which are likely to experience normal to below normal rainfall.
Maximum temperatures are expected to be above normal over most parts of the country except some parts of central and adjoining south peninsular India, IMD said. Minimum or night time temperatures, however, are expected to be above normal over almost all parts of the country, IMD warned.
The northeast monsoon season (October to December) is also expected to be above normal. Rainfall averaged over south peninsular India consisting of 5 meteorological subdivisions (Tamil Nadu, Puducherry and Karaikal, Coastal Andhra Pradesh, Rayalaseema, Kerala and Mahe, and South Interior Karnataka) is most likely to be above normal (>112% of Long Period Average) during the post monsoon season.
During the season, normal to above normal rainfall is likely over many areas of central India, south peninsular India, and some parts of northeast India during the same period. However, most parts of northwest India, and some parts of northeast India and southernmost parts of India are likely to receive below normal rainfall.
Currently, neutral El Nino-Southern Oscillation (ENSO) conditions are observed over the equatorial Pacific Ocean with below average sea surface temperatures in the east equatorial Pacific Ocean. The probability forecast indicates a higher chance of development of La Niña conditions during post-monsoon season, IMD has projected.
Above-average sea surface temperatures (SSTs) are currently seen across most of the Indian Ocean. Currently, neutral Indian Ocean Dipole (IOD) conditions prevail over the Indian Ocean. The latest MMCFS forecast indicates that the neutral IOD conditions are likely to continue during post-monsoon season, IMD added.
“Normally with development of La Nina below normal temperatures are expected during winter. But now in October, models are indicating above normal temperatures over the country. Weak La Nina conditions are expected to develop during this post monsoon season,” said M Mohapatra, director general, IMD.
Globally La Nina forecast went wrong
IMD said that like several other global agencies, its La Nina projections went wrong. Even though IMD had projected that La Niña conditions are likely to develop during second half of monsoon season and positive IOD conditions are likely to develop during the later part of the monsoon season, neutral El Nino conditions developed in July and continued till September. IOD remained neutral till the end of August.
Despite this, monsoon rainfall this year was nearly 108% of LPA. “None of the models globally got La Nina forecast right. But circulation features resembled La Nina which helped monsoon,” said Mohapatra.
The highest number of deaths due to heavy rain and flooding was recorded in Kerala (397) followed by Assam (102) and Madhya Pradesh (100) according to data collated by IMD. During monsoon highest number of lightning deaths were recorded in Madhya Pradesh (189) followed by Uttar Pradesh (138).
Highest heavy rainfall events were recorded this year (525) since 2020.
“One of the major reasons for excess rainfall during monsoon is higher number of low pressure systems that formed. There were 14 low pressure systems (lps), 6 of them intensified into depressions, and there were 69 lps days against a normal of 13 systems and 55 lps days,” Mohapatra explained.
IMD’s analysis also pointed out that west Rajasthan and Saurashtra recorded 71% and 75% respectively during monsoon. “The reason western states recorded very high rainfall this year is because the low pressure systems had longer tracks traversing Odisha, Andhra Pradesh, travelling across central India right up to Gujarat and Saurashtra. These systems also formed slightly to the south of their normal position,” Mohapatra added.
Mohapatra also said that there is a general trend of increasing temperatures during monsoon months with variations across years. “We can see the background impact of climate change. Monsoon months are becoming warmer. We saw that this year too.”
