Northeast monsoon may come by October-end

Peninsular States to get near-normal rainfall, says official

Waiting for cheer: Chennai received some rain over the past two days due to a low pressure area in the Bay .

As the Southwest monsoon recedes, attention is focussed on the potential of the Northeast monsoon to make up for the deficit this year in some parts of the peninsular States, particularly Tamil Nadu. The winter monsoon is likely to have a delayed onset, around the last week of October.

The Northeast monsoon brings significant rainfall to coastal Andhra Pradesh, Rayalaseema, Tamil Nadu and Puducherry.

A well-marked low pressure area lying over central and adjoining south Bay of Bengal is likely to intensify into a depression by Wednesday. This is expected to be the last weather system of the season, as the Southwest monsoon withdraws.

Once it moves towards north Andhra Pradesh and south Odisha coast, the stage would be set for the arrival of the Northeast.

“We expect the northeasterly winds to set in by October 22 or October 23. This would make conditions favourable for the onset of monsoon. While the onset may be delayed by a couple of days, we expect normal rainfall over the entire region,” according to S.B. Thampi, Deputy Director-General of Meteorology, Chennai.

Tamil Nadu receives nearly 44 cm of rain during the Northeast monsoon.

International agencies that rely on various weather models have diverging results in their forecasts. Meteorologists and informed weather bloggers say the European Centre for Medium-Range Weather Forecasts (ECMWF), one of the reliable weather models, and South Asian Climate Outlook Forum indicate close to normal rainfall during the Northeast monsoon, especially for Tamil Nadu.

A team of bloggers under the banner ‘Chennaiyil Oru Mazhaikalam’ interpret the ECMWF and Climate Forecast System of National Centers for Environmental Prediction to mean the monsoon may set in between October 27 and November 2, and follow on vigorously over the fortnight beginning November 7.

Some districts, particularly those along the coast like Karaikal, Kanyakumari and Chennai, need a good Northeast monsoon to touch their normal annual rainfall. There may be four weather events in the Bay of Bengal and Arabian sea from the second half of October to December.

Weather experts also note that the monsoon activity is more important than its date of onset. Y.E.A. Raj said the Northeast monsoon set in around the last week of October during 2015 and 2016.

While 2015 brought torrential downpour, last year’s monsoon witnessed drought.