As the country counts down each summer day and waits for the arrival of monsoon, meteorologists on Tuesday said some of the key atmospheric conditions that have a direct influence on the southwest monsoon are presently favourable.
As the country counts down each summer day and waits for the arrival of monsoon, meteorologists on Tuesday said some of the key atmospheric conditions that have a direct influence on the southwest monsoon are presently favourable.
The India Meteorological Department (IMD) is expected to issue a monsoon forecast some time this week. The monsoon normally reaches Kerala in the first week of June.
In the season’s first stage Long Range Forecast (LRF) issued in April, the IMD had said that the upcoming monsoon will be near normal and rainfall up to 96 per cent of the Long Period Average (LPA) is likely to be received over the country between June and September this year. The Long Period Average (LPA) of the monsoon over the country is 89 cm, calculated for the period from 1951 to 2000.
While there is a weak El Nino prevailing over the Pacific Ocean, IMD officials continue to maintain that it will weaken in the coming months, August onwards.
Importantly, scientists have noted that the latent heat in the key Nino regions (regions along the equatorial Pacific Ocean), measured in terms of Sea Surface Temperatures (SSTs), have not crossed the threshold value as yet. Warmer SSTs along these regions indicate the presence of El Nino, an abnormal warming of the equatorial Pacific Ocean mainly off the west coast of South America. El Nino is known to suppress the southwest monsoon and during El Nino, seasonal monsoon has remained subdued.
“As per the latest reports tracking El Nino, the SSTs have remained stagnant and in some regions, even reported cooling, which is a positive indication so far,” said an official from IMD, Pune.
Yet another key factor is the Madden Julian Oscillation, an atmosphere-ocean-coupled phenomenon in the tropical regions, with equal significance on the southwest monsoon. The MJO activity is tracked over eight phases as it traverses eastwards along the globe, in a time cycle that can last anywhere between 30 and 60 days.
“During the onset phase of southwest monsoon this year, MJO will be close to the Indian Ocean and this location will have a positive influence on the monsoon, particularly as it enters the Indian mainland. There are good chances of enhanced rainfall activity, especially during the onset phase,” said a senior IMD official.
This, if realised, will be crucial for the upcoming monsoon as MJO activity during the previous two monsoons, in 2017 and 2018, according to scientists, had largely remained sluggish. Last year, the monsoon ended with a 9 per cent deficit. “As a result, there was no significant positive influence on the rainfall activity during the entire season in the last two years,” said the senior official.
The India Meteorological Department (IMD) is expected to issue a monsoon forecast some time this week. The monsoon normally reaches Kerala in the first week of June.
In the season’s first stage Long Range Forecast (LRF) issued in April, the IMD had said that the upcoming monsoon will be near normal and rainfall up to 96 per cent of the Long Period Average (LPA) is likely to be received over the country between June and September this year. The Long Period Average (LPA) of the monsoon over the country is 89 cm, calculated for the period from 1951 to 2000.
While there is a weak El Nino prevailing over the Pacific Ocean, IMD officials continue to maintain that it will weaken in the coming months, August onwards.
Importantly, scientists have noted that the latent heat in the key Nino regions (regions along the equatorial Pacific Ocean), measured in terms of Sea Surface Temperatures (SSTs), have not crossed the threshold value as yet. Warmer SSTs along these regions indicate the presence of El Nino, an abnormal warming of the equatorial Pacific Ocean mainly off the west coast of South America. El Nino is known to suppress the southwest monsoon and during El Nino, seasonal monsoon has remained subdued.
“As per the latest reports tracking El Nino, the SSTs have remained stagnant and in some regions, even reported cooling, which is a positive indication so far,” said an official from IMD, Pune.
Yet another key factor is the Madden Julian Oscillation, an atmosphere-ocean-coupled phenomenon in the tropical regions, with equal significance on the southwest monsoon. The MJO activity is tracked over eight phases as it traverses eastwards along the globe, in a time cycle that can last anywhere between 30 and 60 days.
“During the onset phase of southwest monsoon this year, MJO will be close to the Indian Ocean and this location will have a positive influence on the monsoon, particularly as it enters the Indian mainland. There are good chances of enhanced rainfall activity, especially during the onset phase,” said a senior IMD official.
This, if realised, will be crucial for the upcoming monsoon as MJO activity during the previous two monsoons, in 2017 and 2018, according to scientists, had largely remained sluggish. Last year, the monsoon ended with a 9 per cent deficit. “As a result, there was no significant positive influence on the rainfall activity during the entire season in the last two years,” said the senior official.