E-Paper
Monsoon to see brief revival over east central India, forecasts IMD
There were 20 break monsoon days in August compared to 16 in 2005 which was the previous record for highest break days when the monsoon is extremely weak
Following a prolonged period of weak monsoon conditions in August, it is expected to pick up briefly for 2-3 days this week but weaken again thereafter, meteorologists have said.
According to the weather experts, there is an 11% deficiency in monsoon rainfall over the country, with a 12% deficiency over central India, a 14% deficiency over peninsular India, an 18% deficiency over east and northeast India and a 0% deficiency over north-west India as of Sunday.
The Indian Meteorological Department’s (IMD) drought indicator shows large parts of the country are recording mild to moderately dry conditions.
HT reported on August 31 that this August was the driest and warmest for the entire country since weather records began being kept in 1901.
There were 20 break monsoon days in August compared to 16 in 2005 which was the previous record for highest break days when the monsoon is extremely weak.
IMD’s long-term data indicates there has been a gradual increase in break monsoon days in recent years. The highest previous record of rainfall deficiency in August was in 2005 (25%), this year it was 36% in August.
A cyclonic circulation is lying over the northeast Bay of Bengal and the neighbourhood, say meteorologists. Under its influence, a low-pressure area is likely to form over the northwest and adjoining west-central Bay of Bengal during the next 48 hours, the IMD said on Sunday.
The monsoon trough at mean sea level continues to run along the foothills of the Himalayas. Its eastern end is likely to shift southwards to its normal position from Monday and to the south of its normal position thereafter, it said.
In association with these features, active monsoon conditions are likely over north Peninsular India, Odisha and Chhattisgarh during the next 2-3 days. There is likely to be an increase in rainfall activity with isolated heavy rain over northeast India, Madhya Pradesh and Maharashtra from September 5, the weather department further informed.
All India monsoon seasonal average is running “deficient”, at 11% below normal. In the pre-2016 era, this would have been called an “All India drought”.
“District-wise maps show widespread deficit across India, except northwestern districts of Gujarat and Rajasthan,” Roxy Mathew Koll, a climate scientist at the Indian Institute of Tropical Meteorology, wrote on X (formerly Twitter) on September 1.
The ‘drought’ category was changed to the ‘deficient’ category in 2016 by the IMD. Monsoon rainfall between 96% and 104% of LPA is considered normal, while rainfall between 90% to 95% of the long-period average is considered to be in the ‘below normal’ category and less than 90% is considered ‘deficient’.
IMD’s cumulative standard precipitation for the period of June 1 to August 30 shows most districts in the country are mild to severely dry. Around 13% area is moderately dry; around 5% area is severely and extremely dry and around 40% of the country’s area is mildly dry as per the index.
The Standardized Precipitation Index (SPI) is the most commonly used indicator worldwide for detecting and characterizing meteorological droughts. The SPI is used for estimating wet or dry conditions based on precipitation variables. It mainly reflects soil moisture and rainfall conditions for a particular location
“Rainfall deficit pattern of 2023 is similar to the long-term declining trend of the monsoon— both denoting a weak monsoon circulation (in response to El Niño/Indian Ocean warming),” said Koll, referring to findings of a 2015 paper by Indian Institute of Technology Madras (IITM) which found that there is a significant weakening trend in summer rainfall during 1901–2012 over the central-east and northern regions of India, along the Ganges-Brahmaputra-Meghna basins and the Himalayan foothills, where agriculture is still largely rain-fed.
The report found that the land-sea thermal gradient over South Asia has been decreasing due to rapid warming in the Indian Ocean and relatively subdued warming over the subcontinent. Enhanced Indian Ocean warming potentially weakens the land-sea thermal contrast, dampens the summer monsoon circulation, and thereby reduces the rainfall over parts of South Asia.
“With the formation of the low-pressure area over the Bay of Bengal, there is likely to be rainfall over Bihar, Jharkhand, West Bengal, Odisha, east Uttar Pradesh, and Chhattisgarh for the next 2-3 days. There may be some rainfall over Telangana, Vidarbha and Marathwada but thereafter monsoon conditions will weaken again. There will also be no rainfall over western parts of the country during the next 2-3 days. Rains will be limited to east-central parts,” said Mahesh Palawat, vice president, of climate and meteorology at Skymet Weather.
“After this spell, monsoon will gradually move towards the withdrawal phase so we are not expecting any major rainfall activity thereafter,” added Palawat.
M Rajeevan, former secretary of the ministry of earth sciences said the favourable phase of Madden Julian Oscillation (MJO) may help monsoon during the first half of September but not thereafter. The MJO is characterised as an eastward moving ‘pulse’ of cloud and rainfall near the equator that typically recurs every 30 to 60 days.
“At present things are not good. They are close to drought conditions at many places even though we cannot liberally use the term drought. Almost 40 % of districts are under the deficient category. Not a good sign. But with the ensuing active phase, things will improve substantially, especially over central and northern parts. There is a possibility of an active spell over central India during the next 10 days or so. This is a good sign. This is due to a favourable phase of MJO. But a weak spell may be expected during the second half of September,” added Rajeevan.
Isolated very heavy rainfall is also likely over coastal Andhra Pradesh on September 4 and 5 and over Telangana from September 3 to 5, the IMD has said.
Over central India, light to moderate and widespread rainfall, thunderstorms and lightning with isolated heavy rainfall are very likely over West Madhya Pradesh on September 6 and 7; East Madhya Pradesh and Vidarbha from September 5 to 7 and over Chhattisgarh from September 3 to 7, added the weather department.
