India may end up with a slightly higher-than-average monsoon, rather than a surplus one, the state-run weather bureau’s latest observations show.
Two climatic factors that can drive the monsoon to excess levels are turning out to be moderate, which means heavy flood-category rains are unlikely towards the second half.
Widespread flooding in several states after heavy showers has rendered thousands of people homeless over the past month. Central Indian states have got 9% surplus rainfall, while the northern states have received normal rains. Eastern and north-eastern states have, however, received 11% deficient rains so far. Overall, the monsoon currently is “normal” with 0% surplus.
The Met department in its official forecast had predicted excess rains, with heavier falls towards the second half of the June-September monsoon rainy season.
The rains would be 106% of the 50-year average of 89 cm, the Met had predicted, with an error margin of +/-4%. The monsoon is normal if it is 96-104%. Between 104-110%, it is considered above normal.
A strengthening La Niña, a weather pattern marked by a progressively cooling Pacific Ocean, was projected to cause higher-than-normal rainfall.
While the Pacific is likely to continue to be cool, La Niña conditions haven’t taken hold. A strong La Niña could adversely damaged farm output due to flooding due to excessive rains.
“In the tropical Pacific Ocean, recent model outlooks indicate a reduced chance of La Niña in 2016. Most climate models indicate the central Pacific Ocean will continue to cool, but only two of eight models show La Niña values through the southern spring,” an update from the Australian Bureau of Meteorology said. The Met’s observations too show similar conditions, an official said, interpreting the data.
Another key parameter, the Indian Ocean Dipole (IOD) is currently “negative”, which is associated with less rains. The IOD is the difference in sea-surface temperature between two spots in the Indian Ocean. If the IOD stays “positive or a neutral”, monsoon rainfall stays on the higher side. The IOD is currently on track to becoming negative.
“The net effect of these conditions means the rainy season would mostly likely be normal,” he said.