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The Myanmar Department of Meteorology and Hydrology may have become the first national forecaster in the region to issue an outlook for the first low-pressure area of the 2020 pre-monsoon season in the Bay of Bengal.
Its 10-day outlook dated April 18 said that a low-pressure area, a basic standard feature of an organised weather system that can grow into potential storms, may form over the Andaman Sea and South Bay of Bengal over the next 10 days.
Global models see cyclone
The India Meteorological Department (IMD) may not have said as much in as many words, but its wind profile maps do agree with the Myanmarese agency indicating the possibility of a low-pressure area forming over South-East Bay of Bengal and the adjoining Andaman Sea around April 29-30.
A number of global weather models have forecast this low-pressure area may intensify into a cyclone in the Bay and move towards Myanmar/Bangladesh. The IMD, which is also the Regional Specialised Meteorological Centre for Tropical Cyclones over North Indian Ocean (the Arabian Sea and the Bay of Bengal), is yet to take a call.
MJO wave enters Indian Ocean
What sets these in perspective is the arrival of a rain and storm-boosting Madden-Julian Oscillation (MJO) wave in the West Indian Ocean. MJO waves periodically travel from the West Indian Ocean to the East and later into the Pacific with their entourage of lower pressure, ascending clouds, moisture and precipitation. They have been known to signal the onset of the monsoons, low-pressure areas and storms.
According to the Australian Bureau of Meteorology, a moderately strong pulse of the MJO is currently located over the West Indian Ocean and is expected to extend its influence over the entire Indian Ocean (including Arabian Sea and the Bay of Bengal) for a week till April 26. Most climate models are in good agreement with this. This would also help ignite further the pre-monsoon thunderstorms over Kerala and Sri Lanka.
Pre-monsoon rain peak
This also brings into focus the genesis of the pre-monsoon rain peak (PMRP), a crucial seasonal feature signalling the establishment of a band of raining cloud extending from Kerala into the Bay of Bengal, and propounded by PV Joseph, eminent monsoon researcher and former director of IMD. The PMRP should start consolidating from April 21 every year for the successful and timely onset of the larger South-West monsoon over Kerala around its normal date of June 1. Satellite maps on Tuesday (April 21) indicate that this process may well have been initiated.
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