IMD: Despite El Nino, 73% areas received normal rain in June-Sept
In July, a weak El Nino prevailed, which later intensified into the moderate category during August and September, the IMD said. According to the Met Department's data, there were 15 low-pressure systems, against a normal of 13, that formed during June to September.
“Most of these systems developed during July and September in the Bay of Bengal, during which the country’s rainfall over large parts were above normal,” said the IMD chief. The India Meteorological Department (IMD) on Saturday said the country recorded normal rainfall, despite El Nino, during June to September. With the end of the southwest monsoon season, quantitatively, the all-India rainfall was 94.4 per cent of the Long Period Average (LPA).
Though the year began with the emergence of El Nino conditions — the abnormal warming of the equatorial Pacific Ocean and linked to causing subdued rainfall over large parts of India — and its rapid intensification between March and May, there were multiple other factors that countered the likely adversity posed by El Nino, IMD officials said.
“The favourable phase — the Madden Julian Oscillation (MJO), the positive phase of the Indian Ocean Dipole (IOD) and higher than normal number of low pressure systems and their movement — helped counter the effect of El Nino,” said Mrutyunjay Mohapatra, Director General, IMD.
In July, a weak El Nino prevailed, which later intensified into the moderate category during August and September, the IMD said.
According to the Met Department’s data, there were 15 low-pressure systems, against a normal of 13, that formed during June to September. As a result, there were 65 days when the country remained under the influence of low-pressure systems whereas the normal is 55 days.
“Most of these systems developed during July and September in the Bay of Bengal, during which the country’s rainfall over large parts were above normal,” said the IMD chief.
This season, nearly 73 per cent of the country’s geographical area, or 26 meteorological sub-divisions, recorded normal rainfall. Whereas, about 9 per cent geographical area, largely over Rajasthan and Gujarat, recorded excess rainfall during the past four months.
Regions covering Kerala, south Karnataka, Nagaland, Mizoram, Tripura, Gangetic West Bengal, Bihar, Jharkhand and eastern Uttar Pradesh – measuring about 18 per cent of the country’s geographical area – ended with significant rainfall deficiency.
In fact, northeast India recorded normal rainfall (+2 per cent) only in August, whereas during the rest of the months the rainfall deficiency ranged from -15 per cent (June), -22 per cent (September) and -32 per cent (July). Similarly, the southern peninsular India’s monthly rainfall was -45 per cent (June), +45 per cent(July), -60 per cent(August) and +24 per cent(September).
Manipur (-46 per cent) and Kerala (-36 per cent) ended up being two of the most rain-deficient states. Kerala suffered mainly due to an inactive Arabian Sea, explained Mohapatra.
“The Bay of Bengal remained more active than the Arabian Sea in the past four months. As a result, the low-pressure systems brought rainfall over most areas of the country, including central India. However, due to the lack of formation of monsoon troughs along India’s west coast, Kerala, where rainfall normals are high, remained devoid of good rainfall,” he said.
Among the other rainfall-deficit states were Mizoram (-28 per cent), Bihar and Jharkhand (-26 per cent each) and Assam (-20 per cent).
This year, August (-36 per cent) fared as the worst rainfall month, the driest since 1901.
“This was a historic deficiency ever experienced by the country. Even though IMD’s forecast had warned of below-normal rainfall activity, the models could not estimate it to be around 36 per cent,” said the Met Department chief.
Exceptionally high rainfall was recorded at many places in Gujarat, Himachal Pradesh, Delhi, Maharashtra, Rajasthan and Telangana. The associated 24-hour rainfall recorded on some days went as high as 650 mm (Mulugu), 540 mm (Gir Somnath), 450 mm (Bhimpur), 400 mm (Raigad) and 200 mm (Chandigarh).
Presently, moderate El Nino conditions, with the Nino 3.4 region reporting the Nino index value of 1.7 degree Celsius, prevail.
“The global models forecast indicates that El Nino conditions will continue to prevail till March 2024, with its intensity fluctuating from moderate to strong during the coming months. With respect to IOD, it will remain in the positive phase till the year-end,” Mohapatra said.
Meanwhile, the southwest monsoon withdrawal continues to progress and there are favourable conditions building up for its exit from parts of Jammu and Kashmir, Himachal Pradesh, more parts of Rajasthan, west Uttar Pradesh, west Madhya Pradesh and some parts of Gujarat during the next three to four days.
This year, the southwest monsoon is most likely to exit from the country close to its normal date of October 15, the Met Department said.
Normal rain during northeast monsoon: IMD
The country is most likely to receive normal rainfall during the upcoming northeast monsoon season, the IMD said on Saturday. Quantitatively, it could range from 88-112 per cent of the Long Period Average. This winter monsoon is largely beneficial for the southern peninsular India. “This year, the rainfall deficient states can make up during the upcoming season,” said IMD DG Mrutyunjay Mohapatra.
Anjali Marar works at Raman Research Institute, Bengaluru
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