Depression over Odisha coast to cause intense wet spell

THE TROUGH WILL REMAIN IN ITS CURRENT POSITION OVER THE NEXT THREE DAYS, THE WEATHER FORECASTER SAID

A depression formed over coastal Odisha is likely to cause an intense wet spell over Odisha, Chhattisgarh, Vidarbha, Gujarat, Konkan, Goa and ghat areas of Madhya Maharashtra on Wednesday and Thursday, the India Meteorological Department (IMD) has said.

The monsoon trough, an elongated area of low pressure that usually spans from Pakistan to West Bengal, is active and lying south of its normal position, the IMD said. A position south of normal indicates heavy rainfall over central India.

The trough will remain in its current position over the next three days, the weather forecaster said.

A well-marked low-pressure area over coastal areas of Odisha and northwest Bay of Bengal moved slowly west-northwest concentrated into a depression and lay centred about 70 km north-northwest of Bhubaneswar on Tuesday, the agency said.

The depression is likely to move gradually west-northwestwards, maintain its intensity on Tuesday and then weaken into a well-marked low pressure area over Chhattisgarh and neighbourhood on Wednesday. An east-west shear zone is running over north peninsular India in the middle tropospheric levels. It is likely to persist during next 3-4 days.

In a shear zone the easterly winds move to the north and the westerly winds to the south. This is an area of high convergence according to IMD officials.

“With the intensification of the low-pressure area, we can expect intense rainfall over central India. Due to strong winds from Arabian Sea, a very intense shear zone has formed which is bringing heavy and widespread rain to Maharashtra, particularly Mumbai. This shear zone may intensify further to a vortex in the next 2 days which can bring heavy rains over a larger area. This rain over west coast including Mumbai for next 2-3 days. The depression has shifted slightly north so isolated heavy rain is expected over Jharkhand and West Bengal also but not much. Main impact zone of this system is central India,” explained Ananda Das, in charge of cyclones at IMD.

The west coast has an orographic barrier in the form of Western Ghats. When monsoon winds strike the mountains, on many occasions, they do not have enough energy to climb over the ghats. On such occasions, they tend to be deflected round the mountains and the return current forms the offshore vortex. These vortices are responsible for the occurrence of heavy to very heavy rainfall over west coast during monsoon season, according to IMD.

There is a red category warning for entire central India stretching from Odisha to Maharashtra and Goa on Tuesday and orange category warning for the region on Wednesday. These warnings are for local authorities to take action to prevent extreme rain related disasters.