The India Meteorological Department (IMD) has declared a watch for a depression off the Odisha-West Bengal coasts likely by Friday, the second during post-monsoon, as a prevailing low-pressure area over the Central Bay of Bengal undergoes gradual intensification by that time.
Fairly widespread to widespread rainfall with isolated heavy falls is forecast over Coastal Andhra Pradesh, Rayalaseema, Telangana and Odisha until Friday; over plains of West Bengal on Thursday (tomorrow); and over North-East India from Friday to Monday.
Very heavy rain for North-East
Isolated very heavy rainfall is likely over Coastal Odisha and adjoining Coastal West Bengal on Thursday. Isolated heavy to very heavy rainfall with extremely falls is forecast over Nagaland, Manipur, Mizoram and Tripura on Saturday; and over Assam and Meghalaya on Monday.
To the further South, fairly widespread to widespread rainfall with isolated heavy falls has been forecast over Karnataka into the weekend; and over Tamil Nadu and Puducherry until tomorrow (Thursday). A fishermen alert is valid over the Bay of Bengal along the Andhra Pradesh-West Bengal coasts.
The low-pressure area has been persisting over the central parts of the Bay from Tuesday, which is expected to intensify a round to become ‘well-marked’ on Thursday (tomorrow) over the West-Central Bay off the Andhra Pradesh coast, the IMD said this (Wednesday) morning.
Low-pressure area to recurve
In the process, it would start recurving away from the Andhra Pradesh coast and move to the North-North-East over the West-Central Bay towards the North-West Bay off the Odisha-West Bengal coasts and concentrate into a depression by Friday while based on the waters.
The recurving away from the Andhra Pradesh coast would be overseen by the interplay of a western disturbance and the seasonal anticyclone parked at different levels over North-West India. The western disturbance was spotted over North Pakistan and Jammu & Kashmir this morning.
This away-movement would allow the easterly to north-easterly winds from the brewing depression and the north-westerly-to-north-easterly winds from the anticyclone to align and set up a helpful environment for monsoon transition both over land and the Arabian Sea.
Longer wait likely over Bay
But the short-to-medium term projections by the IMD suggest that it would take longer for the winds to suitable align over the Bay of Bengal to help with the wholesale transition from South-West monsoon to North-East monsoon over the South Peninsula and adjoining North Peninsula.
Conditions are gradually becoming ideal for the South-West Monsoon to withdraw from Uttar Pradesh and Bihar; northern West Bengal and Sikkim; Jharkhand; Madhya Pradesh; northern Chhattisgarh and Maharashtra; Gujarat; North Arabian Sea; and parts of Central Arabian Sea.