IMD cites weather dynamics for change
In a sudden turn of events, the Meteorological department has announced that the northeast monsoon will be delayed and conditions are not favourable for its onset on Monday, as predicted earlier.
The changing dynamics due to the two weather systems prevailing in the Arabian Sea and the Bay of Bengal have led to the delay in the onset of the monsoon over Tamil Nadu.
The cyclonic storm ‘Luban’ over west central and adjoining southwest Arabian Sea is likely to intensify into a severe cyclonic storm by Tuesday and move towards south Oman and the Yemen coast in the next five days.
Moreover, the weather system in the east-central Bay of Bengal is expected to become a deep depression and turn into a cyclonic storm by Wednesday.
This would move towards Odisha and the north Andhra Pradesh coast.
Normally, the monsoon sets in over the State around October 20. S. Balachandran, Deputy Director General of Meteorology, Regional Meteorological Centre, Chennai, said the interactions between the systems had influenced the wind direction and distribution of moisture in Bay of Bengal, Arabian Sea and the southern peninsula.
“We need sustainable easterly winds for the onset of the northeast monsoon. The changing wind and moisture pattern will delay the monsoon for some more days,” he said.
Only after the lifecycle of these two systems comes to an end, the onset [of northeast monsoon] with a new weather disturbance was expected, he added. This would bring down the rainfall over the State after October 10.
During the 24 hours that ended at 8.30 a.m. on Monday, the weather stations in Tirupuvanam in Sivaganga district recorded the highest rainfall of 15 cm.
Warning to fishermen
The Meteorological department forecast that Tamil Nadu and Puducherry may experience moderate rainfall of up to 4 cm in many places; one or two places in north Tamil Nadu may see heavy rainfall up to 12 cm till Wednesday. Chennai too may witness intermittent spells of light to moderate rainfall till Wednesday after which there may be a break.
The department has also warned fishermen not to venture deep into the Arabian Sea and central and north Bay of Bengal till October 10.
Responding to a query on whether the ‘extremely heavy rainfall’ warning that was issued recently was motivated politically, Mr. Balachandran said it was done only based on weather models and climate data.