The Hindu Business Line : Monsoon onset over Kerala around May 24

Thiruvananthapuram May 14 Southwest monsoon is expected to break along the Kerala coast at least a week ahead of the normal date of June 1, matching the lead with which the Bay of Bengal branch made its onset earlier last week.

The India Meteorological Department (IMD) on Monday said that monsoon predictors signalled the Arabian Sea branch making an onset on May 24, with a model error of three days.

Various international weather models had earlier come out with projections that the monsoon would hit the mainland early this year and generate normal or even above normal rainfall during the four-month season that ends in September.

La Nina effect

These projections were largely based on the rollout of a `rare oceanic double' this year - a nascent La Nina in the equatorial and east Pacific and a positive Indian Ocean Dipole in the opposite direction, towards the west.

La Nina is the colder counterpart of El Nino, in which warming anomalies return to west Pacific/South China Sea, is in close proximity to the Bay of Bengal. La Nina years have mostly coincided with a successful Indian monsoons, though there is no established correlation between the two.

The Indian Ocean Dipole represents a seasonal seesawing of sea-surface temperatures (SSTs) in the equatorial Indian Ocean and has a better influence on the monsoon. In a positive Indian Ocean Dipole phase, southwest Indian Ocean gets warmer relative to the southeast, with positive implications for monsoon.

There is no one to one correspondence between the monsoon onset date over Kerala and subsequent rainfall during the season over the country as a whole.

Similarly, an early onset over Kerala does not suggest an early monsoon onset over the interior parts of the country, especially over the North

More Stories on : Climate & Weather | Kerala | Outlook

Article E-Mail :: Comment :: Syndication :: Printer Friendly Page