ENSO neutral conditions continue over the Pacific and equatorial sea surface temperatures are near to below average across the central to the eastern Pacific Ocean. A La Nina watch already been posted since the beginning of August. The model forecast broadly has a consensus of La Nina with over 60% probability by the fall of the year. These conditions may continue till winters with the gradual decline and drop below the threshold only by Feb/Mar 2021.
Indian Ocean Dipole(IOD), also called the Indian Nino is a strong driver of monsoon rains. As against the early predictions of -ve IOD this season, the index stood +ve, though marginal during the first half of the season. Off late, this parameter is quite volatile and the fluctuations are large. The current value has crossed the negative threshold of -0.4 and stands at -0.68. A negative IOD is not considered favorable for the enhancement of monsoon rains. The model projection suggests the IOD will remain -ve during the month of September.
Madden Julian Oscillation is another oceanic index. It is a circumpolar index and traverse in the equatorial belt. Though transient in nature, it has the potential to suppress or aggravate the monsoon surge depending on its position. An active MJO when positioned over the Indian Ocean has the capacity to energize the monsoon current. In the remaining days of August, it is going to stay in the close proximity of the Indian Ocean (over the African continent) with moderate amplitude.
Monsoon has its own forcing which can revitalize the spread and intensity of rains with its internal dynamics. The ‘Monsoon Trough’ has fortified the seasonal rains against the usual ‘break’ commonly seen in July and August. The frequent formation of monsoon systems in the Bay of Bengal has drenched most parts during the core monsoon months.
The month of August is holding a surplus of 16% and has compensated for the shortfall of July. Monsoon seems to be heading for a fair deal this season and is likely to put up a spirited display during the upcoming month of September.