Pre-monsoon rain is peaking over Kerala as heavy to very heavy rain lashed many places of the State during the 24 hours ending Tuesday morning and later into the day.
This represents the ‘pre-monsoon rain peak,’ culmination of a chain of events triggered by the warming of the south Bay of Bengal and leading up to the breakout of thundershowers over Kerala, gateway for the South-West monsoon.
An India Met Department update said that rainfall occurred at a few places over south Tamil Nadu during the 24 hours ending Tuesday morning.
Isolated rainfall was reported from north Tamil Nadu, coastal and south interior Karnataka.
Its outlook suggested that heavy rain could continue to lash Kerala through the rest of the week.
The US Climate Prediction Centre is of the view that rains, though of lesser intensity, would be the predominant theme here until the month-end. The proximate cause appears to be a persisting cyclonic circulation over Maldives-Lakshadweep.
MJO wave What is likely making it roar into hectic activity is a passing Madden-Julian Oscillation (MJO) wave to the south of Maldives and Sri Lanka.
The wave travels periodically from west to east from east African coast, wades into the Indian Ocean, and is bound for South China Sea/west Pacific in due course.
The slow-moving wave traverses the high altitude, but can set up cloudiness, storms and even cyclones at the ground-level, and is also known to trigger the onset of monsoon.
Weather watchers keep a close track of the wave to seek out its movement around the time the monsoon is scheduled to make the onset over Kerala, which is June 1.
Rain in North-East As of Tuesday, the peak cloudiness associated with the MJO hung mostly around Sri Lanka with a heavy limb extending across the Comorin region into Kerala and neighbourhood.
Apart from Kerala and neighbourhood, the other rainfall peak was located by the US Climate Prediction Centre to over the north-eastern States.
Already hosting the seasonal ‘kalbaisakhi’ thundershowers, these States have been marked out as a potential region for heavy rain during this week as well as into the next.
Elsewhere, heat wave conditions prevailed over Saurashtra and Kutch but seemed to have ejected out of Rajasthan, thanks to the presence of a western disturbance over Jammu and Kashmir.