As anticipated earlier, a tropical depression( TD29) has formed over southern parts of Gulf of Thailand and adjoining east coast of Malaysia. Currently, it is centered around 4.2°N and 103°E, about 300km north-northwest of Singapore. TD-29 is likely to move westward and move across central parts of Malaysia.
It is expected to weaken to a low pressure area, on reaching west coast of Malaysia and neighboring Strait of Malacca. The weather system is likely to remain over Strait of Malacca and adjoining Malay Peninsula and South Andaman Sea on 18th and 19thDecember, without any further intensification.
In the meantime, under the influence of existing cyclonic circulation over central parts of South Bay of Bengal, conditions are becoming favorable for formation of a low pressure area (94B) over the same region . This weather system is expected to form in the next 24hr over Southeast Bay of Bengal in the proximity of Bay Islands. Subsequently, it is likely to move northeastward towards South Andaman Sea.
Both these systems are expected to merge on 19thDec and a broad cyclonic circulation will be marked covering South Andaman Sea, Malay Peninsula and Strait of Malacca. It is likely to move northeastward towards border areas dividing southern strip of Thailand and northern parts of Malaysia, on 20thDec. The weather system will move further eastward over southern parts of Gulf of Thailand on 21stDec and become less marked.
As reiterated earlier, these equatorial latitudes are not favorable for strengthening of weather disturbances. Lack of ‘Coriolis Force’ and vertical wind shear suppress intensification of low pressure areas. Accordingly, despite merger of the two systems, unfavorable environmental condition will decay the process.
Heavy rainfall is likely over Bay Islands between 18th and 20th December. South Andaman Sea housing Nicobar Islands will be more vulnerable than North Andaman and Port Blair for inclement weather conditions, more so on 19thDecember 2021.