Every year, several opinions are made before the onset of Southwest Monsoon over the Indian mainland. However this year, we had seen a general consensus among various weather agencies across the world well before the commencement of Monsoon that the season will see above normal rains.
But now the question is how good will the Monsoon 2016 perform?
Skymet Weather had initially given a forecast of 105% of long period average for four-month long season, which was later on upgraded to 109% owing to the weather models pointing towards strong Monsoon.
While India’s nodal agency, Indian Meteorological Department, maintains it at 106%. Further, few other agencies have also predicted that the ongoing Monsoon season may end up with excess rains to the tune of 112%.
Since 1950, there have been only eight years that have witnessed excess rainfall. Out of these eight years, three have fallen in the 50s, i.e., 1955, 1956 and 1959.
While the year 1988 tops the list with excess rains to the tune of 19.3%. The last time Monsoon rains were in excess was 22 years ago in 1994, which was excess by 12.5%.
As per the statistics available, on an average, at least one excess Monsoon was witnessed in a decade till 1990s. But the weather pattern seems to have changed its track as we have not seen any excess Monsoon ever since we have entered in 21st Century.
On the contrary number of droughts have increased since then. There have been five droughts against the long period average of one drought per decade.
According to AVM GP Sharma, President-Meteorology, Skymet Weather, “Everything in nature follows a cycle, be it El Niño, drought or excess Monsoon. This year, several Monsoon governing factors are indicating towards excess rains.”
Let us have a look at the following factors that will possibly lead to excess Monsoon conditions:
Devolving El Niño and evolving La Niña: El Niño had been playing spoilt sport since last two years, resulting in two consecutive droughts. But the good news is that the strongest El Niño on record is declining now. Pacific has turned neutral in Niño 3.4 region which is directly associated with the Southwest Monsoon.
We are now heading towards La Niña that might only commence by the fag end of the Monsoon. The La Niña is invariably linked with good Monsoon rains, varying from normal to above normal rains. Moreover, any La Niña after a strong El Niño has great potential of giving rise to above normal or excess rainfall.
Indian Ocean Dipole (IOD): This is another factor that governs the performance of Monsoon. IOD is in neutral state at the moment and is likely to stay neutral for some more time. And as indicated, it is not likely to hamper Monsoon rains this year.
Also with El Niño going neutral and La Niña building up, any chance of negative impact over Monsoon via IOD also fades away.
According to G P Sharma, “Combination of El Niño and negative IOD can have adverse effect over the Monsoon. However, alone IOD cannot not have adverse impact on the Monsoon rains.”
Following table will show the present status of IOD:
Madden-Julian Oscillation (MJO): The Madden-Julian Oscillation is likely to enter the Indian Ocean shortly, which will be another favourable factor for the Southwest Monsoon.
MJO is a pulse of clouds, rains and winds moving around the globe in the equatorial belt. As per weathermen, whenever MJO moves closer to the Indian Ocean, the convective activity mainly remains confined to the India region.
Let us have a look at the following figure showing the MJO forecast:
Climatology: Climatological factors also suggest that we would observe an excess and a stronger Monsoon.
Looking at the above-stated factors, Skymet Weather is hopeful for quite a good and strong Monsoon. We have already predicted 109% of long period average with error margin of +/- 4% that makes its a win-win situation for Monsoon 2016.
Countdown for Monsoon rains has already started from June 1. However, the first week of Southwest Monsoon ended with deficit rain of 27%. This can be attributed to the remnants of El Niño as the three monthly average of Nino 3.4 is still lingering at 1.1°C. The secession of the current episode will take place when this particular value comes below 0.5°C.
But this cannot be considered as a setback as invariably neither all the Monsoon months fail, nor they go for excess rains. As per Skymet Weather, Monsoon surge is expected to pick up pace as it proceeds. The second half of the season is likely to shade much better than the first half.
Image credit: info.rforests.tripod.com
Any information taken from here should be attributed to skymetweather.com
