Monsoon watch. Weak monsoon conditions may end in the next two days

The current weak monsoon condition is expected to end over the next two days with the formation of a helpful cyclonic circulation over North-West and adjoining West-Central Bay of Bengal, off the Andhra Pradesh-Odisha coasts, which may trigger fresh rain activity over Central and East India.

This circulation will once again coax the eastern end of the monsoon trough over land to shift southward from Friday and likely anchor the cyclonic circulation in the Bay. The western end, too, will move south in tandem, bringing the entire trough back across the plains of North-West India.

Skymet sees ‘low’ forming

Private forecaster Skymet Weather predicts that the cyclonic circulation will manifest itself in the medium levels of the atmosphere before descending to the lower levels and precipitating a low-pressure area by Sunday (August 29). The monsoon trough, too, is expected to drop southward, leading to cessation of the ongoing intense weather activity over Assam, Meghalaya and Arunachal Pradesh.

This will, in turn, set the ground for a late-August burst of rainfall for East and Central India after much of the month failed to deliver since larger atmospheric features had forced powerhouse Bay into a lull. Rain-driving low-pressure areas didn’t breed enough as a result.

Negative IOD factor

Likely causative factor is the negative phase of the Indian Ocean Dipole (IOD), which has an immediate impact on the monsoon if only because of the proximity to the subcontinent. Signals from far-off Central or East Pacific, which itself is in a transitionary phase, have been muted, if at all.

The US Climate Prediction Centre said that the robust Madden-Julian Oscillation (MJO) wave of July and early-August had weakened recently due to interference from other modes of tropical variability. Periodical MJO waves, which move from West to East, have a major impact on monsoon rainfall.

‘Subdued rain regime’

India Meteorological Department (IMD) said that a ‘subdued rain regime’ may continue over North-West, Central India and West Coast during the next four days. Enhanced rainfall trend may persist over North-East India, hills of West Bengal, Sikkim, Bihar, East Uttar Pradesh and Uttarakhand.

In the short term, widespread rainfall activity with isolated heavy to very heavy falls is forecast over North-East India, hills of West Bengal and Sikkim till Friday. Fairly widespread to widespread rainfall with isolated heavy to very heavy falls is likely to continue over Uttarakhand till Sunday.

Isolated heavy falls are forecast over Bihar and East Uttar Pradesh till Friday. Scattered to fairly widespread rainfall with isolated heavy falls over Tamil Nadu during the next five days (familiar pattern during weak monsoon conditions elsewhere), and over Kerala and Mahe from Friday to Sunday.

COMMENT NOW