The forecast phase of expansive monsoon from the weekend is very much in the making, with a fresh wave of rains projected to approach the West Coast soon. A long-persisting low-pressure area off Oman coast flared up on Tuesday, taking away clouds and moisture and holding back intensity of rain over India’s West Coast.
Fresh rain-maker ‘low’s are expected to spring up over both Arabian Sea and Bay of Bengal, international weather models indicated.
CYCLONIC WHIRLS
India Met Department said on Tuesday that preparatory upper air cyclonic circulations have formed over South Bay and West-central Arabian Sea.
Rains over the West Coast and adjoining interior would prosper despite even the fresh Arabian Sea ‘low’ moving away yet again to Oman coast.
European Centre for Medium-Range Weather Forecasting showed another system parked over North Arabian Sea off the Gujarat coast next week.
Australian Bureau of Meteorology said that the monsoon onset over the Kerala coast was facilitated by a weak Madden-Julian Oscillation (MJO) wave.
NEGATIVE PHASE
The MJO wave passes high periodically over the Indian Ocean from west to east and sets off clouding, rain and storms, apart from monsoon onsets.
This wave may now be developing and gaining in strength, which explains the fresh wave of expected rain across South Arabian Sea and Bay of Bengal.
The Australian bureau also said that a negative phase of Indian Ocean Dipole was developing, which has already led Japanese counterparts to doubt the health and prospects of the monsoon.
Four of the five models surveyed point to a negative Indian Ocean Dipole, the bureau said.
This phase of the dipole represents rapid warming of the East Indian Ocean off Sumatra, prompting monsoon flows to stream in and rain out moisture at India’s expense.
WEAK LA NINA
The Japanese agency suspected that even June rains could take a hit.
The Australian bureau also concurred with the view that a mild La Nina, a warming trend in the Pacific normally favourable to Indian monsoon, may be evolving.
India Met Department said on Tuesday that the offshore trough, an elongated area of low pressure that acts as a receptacle for monsoon moisture, ran down from Konkan coast to North Kerala coast.
Presence of the trough indicates ‘active’ monsoon conditions along the West Coast.
vinson.kurian@thehindu.co.in