The persisting cyclonic circulation over Lakshadweep has tossed up a low-pressure area with associated southeasterlies, helping sustain rainfall over South Peninsula.
A ‘low' over Lakshadweep should normally direct a barrage of southwesterly winds into the Kerala coast, atypical of monsoon onset conditions.
Only the monsoon is changing over, and has instead brought up an anticyclone into play over Northwest India.
Too big in size, it is forcing flows to be southeasterlies to its south and around the ‘low.' The Busan, South Korea-based Asia-Pacific Climate Centre has said in its latest seasonal outlook that October-December would likely see above normal rainfall over South India, adjoining Bay of Bengal, South-East China and adjoining East China Sea.
This coincides with the northeast monsoon in India, and forecasts for individual months say October could be the wettest of them all.
‘LOW' TRACKERS
Most of the country, except extreme South and South-East Peninsula and parts of the North-East, is expected to receive good rainfall during this month. Business Line surveyed a slew of specialised ‘low' tracking models - Canadian Meteorological Centre, GFS, UK Met Office, US Navy's NGP – to divine where the Wednesday's Arabian Sea ‘low' is headed.
All of them seemed to suggest it would be taken away to West or North-West from Lakshadweep by the southeasterlies. The system could likely be active for the next two to three days, with the odd model taking it as afar as to Oman/Yemen coast by October 5.
The European Centre for Medium-Range Weather Forecasts (ECMWF) tends to believe that the system might weaken over the next few days. But a sudden wave of activity expected to be triggered in the Bay could ignite it back to activity and cause it to track further north and strengthen.
Alongside, the Bay is also expected to throw up a counterpart system, to set up a trans-peninsular trough from October 6 and likely unleashing some organised showers.
Dedicated models are signalling negative Outgoing Long-wave Radiation (OLR) values indicating cloudiness and resultant rains over East Arabian Sea and South-West and South-East Bay during this period.
EVENTFUL WEEK
The ECMWF sees an eventful week unfolding with a reasonably big ‘weather system' shaping up in the Bay.
A landfall is now being projected along Chennai/South coastal Andhra Pradesh coasts.
The Roundy-Albany model that tracks cyclones sees the system (‘low'/depression) moving north from the South-East and adjoining South-Central Bay.
The Weather Forecasting Centre at the Central Weather Bureau, Taiwan, another specialised storm tracker, has zeroed in on two specific time-scale ‘windows' when the Bay would witness raised churn.
These windows are October 3-7 and October 7-11, when more than one circulation is shown wending their way from the Bay into the South-East Coast of India.
An India Meteorological Department (IMD) update on Wednesday said that widespread rainfall was reported from Coastal Karnataka, South Kerala and Andaman and Nicobar Islands during the 24 hours ending in the morning.
They were fairly widespread over Konkan, Goa and Tamil Nadu and scattered over Sub-Himalayan West Bengal, Sikkim, the Northeastern States, Gujarat, South Gangetic West Bengal and Lakshadweep.
A weather warning valid for Thursday said that isolated heavy rainfall may occur over Lakshadweep, Kerala, Tamil Nadu and Andaman and Nicobar Islands.
Forecast valid until Monday said that fairly widespread rainfall would occur over South Peninsular India while the wet session over North-East India may lift.
Meanwhile, experts are of the view that the Australian monsoon tends to follow the Indian monsoon pattern.
In which case, the northern wet season for the country could get ‘very wet' and active, with La Nina conditions likely to produce an increased number of cyclones.
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