Thiruvananthapuram, Aug. 25
THE new cyclonic circulation expected to form over northwest Bay of Bengal and adjoining Orissa has been deferred by a day to Saturday.
The National Centre for Medium Range Weather Forecasting (NCMRWF) said that the western end of the monsoon trough continued to track the Himalayan foothills, indicating the near-total absence of rain activity over the northwest and even in West-central India.
On Thursday, the eastern end of the trough passed through Bahraich, Gorakhpur, Patna, Bhagalpur and south-eastwards into northeast Bay of Bengal.
During the last 24 hours, fairly widespread rainfall with isolated heavy falls occurred over West Bengal, Sikkim, other north-eastern States, parts of Bihar and east Uttar Pradesh. Chief amounts of rainfall recorded (in cm) are: Dehra Dun 12, North Lakhimpur 10, Kolkata 8, Tezpur 8, Agartala, Sundernagar and Gorakhpur 5 each and Patna 4.
Wednesday's upper air cyclonic circulation over sub-Himalayan West Bengal, Sikkim and adjoining Bihar has become less marked and has left behind a North-south trough running from sub-Himalayan West Bengal and Sikkim to North Bay of Bengal. Under this scenario, the enhanced rainfall activity over the north-eastern States, sub-Himalayan West Bengal, Sikkim and Bihar is likely to continue for another two days.
The upper air cyclonic circulation located over Lakshadweep on Wednesday has become less marked, with a signature offshore trough being observed along coastal Karnataka extending to North Kerala.
Rain for North Kerala: There is likelihood that this trough will stay put over the next 4-5 days, bringing about a gradual enhancement in monsoon flows across the Arabian Sea. This, in turn, is likely to bring scattered rainfall activity over coastal Karnataka and North Kerala during the forecast period.
At the same time, along the East coast, the cyclonic circulation taking shape over the northwest Bay is expected to boost rainfall over Orissa, coastal Andhra Pradesh, Chhattisgarh, Vidarbha, Telangana and Marathwada regions.
In its forecast for the next 4-5 days, the NCMRWF said that the North and the northwest (including Punjab and Haryana) are likely to receive only isolated rainfall.