Much anticipated cyclonic circulation has formed over North Andaman Sea, Gulf of Martaban and adjoining East Bay of Bengal (BoB). It is likely to become organized in the next 24hr. Also, the remnant circulation of tropical storm Lionrock, presently marked over Laos and Thailand, will shift westward and merge with the one over Andaman Sea. Under the combined influence of these two features, a low pressure area is expected to form on 13thOct. This 1st low pressure area of the post monsoon season will move northwestward towards South Odisha and North Coastal Andhra Pradesh in the subsequent 48hr.
Southwest Monsoon has already vacated Northwest India and some parts of Gujarat, Madhya Pradesh, Chhattisgarh and Bihar. During the formation of low pressure and its subsequent movement towards the east coast, the monsoon will withdraw from Eastern and Central parts, exiting Bihar, Jharkhand, Chhattisgarh, Madhya Pradesh, Maharashtra and Gujarat. Two different airmasses, dry retreating monsoon column and maritime moist stream from the BoB, will interact opposingly. This may not allow the low pressure area to move deep inland. Also, further intensification of the low pressure area will be suppressed.
Weather activity in association with this weather system will remain confined to coastal parts of Odisha and Andhra Pradesh and later extend on either side to affect West Bengal and Tamil Nadu. There is another cyclonic circulation over East Central Arabian Sea, tilting southward with height. The shear line joining the above two weather systems will run through the South Peninsular India across Kerala, Rayalaseema, South Interior Karnataka and Tamil Nadu. Pervasive rains can be expected over the entire region for the next 4-5days.
There is another tropical cyclone ‘Kompasu’ in the South China Sea. It is likely to become a typhoon and travel across Philippines, Hainan, Vietnam, Laos and Thailand over the next 5days. The weakened remnants of this system are likely to reach BoB, cutting across Myanmar around 16-17October. This provides lead for yet another system by the end of this week. By then, the withdrawal of monsoon is likely to be complete paving way for its intensification. Bay of Bengal will be under close observation for development of a significant post monsoon system.