Heat wave conditions have abated in North-West India after a remnant low-pressure area left behind by Cyclone Vayu fanned in moisture from the Arabian Sea, bringing light to moderate rains over the region.

However, the prevailing heat wave over isolated pockets in Bihar, Vidarbha, Telangana and South Tamil Nadu may persist for a couple of days more until a fresh ‘low’ pops up over the north Bay of Bengal later this week.

The India Met Department (IMD) expects the monsoon to advance into more parts of Karnataka, some parts of South Konkan & Goa, Andhra Pradesh, Bengal, Sikkim, Odisha, remaining parts of Tamil Nadu and North-East India by the weekend.

Rains for Tamil Nadu

The location of the fresh ‘low’ (likely off the Andhra Pradesh coast) would drag in a fresh wave of South-Westerly and South-Easterly monsoon winds respectively from the Arabian Sea and the Bay, bringing badly needed rain into the region.

An IMD outlook specifically for June 22 (Saturday) said that heavy to heavy rainfall would lash isolated places over Coastal and South Interior Karnataka, Kerala and Mahe. Heavy rainfall is forecast for the day over Chhattisgarh, Konkan & Goa, Coastal Andhra Pradesh and Yanam, Telangana, North Interior Karnataka, Tamil Nadu, Puducherry and Karaikal.

Karaikal (Tamil Nadu), Mahe (Kerala) and Yanam (Andhra Pradesh) are erstwhile French enclaves that currently fall within the jurisdiction of the Union Territory of Puducherry.

An extended three-day outlook from June 23 (Sunday) said widespread rainfall with isolated heavy falls is likely over the South Peninsula and adjoining Central India, the Andaman & Nicobar Islands and North-East India.

MJO impact on ‘low’

Meanwhile, in neighbouring Bangladesh that saw the monsoon make an onset on June 12 - at least 10 days behind schedule, seasonal rains have advanced to its North-Western region, the national weather forecaster said.

The Australian Bureau of Meteorology said on Tuesday that the monsoon-boosting low-pressure band of Madden-Julian Oscillation (MJO) wave has moved past the Bay and strengthened over the Maritime Continent (Indonesia et al).

The MJO wave travels periodically from West to East and influences weather under its footprint setting up clouds, and triggering rainfall, ‘low’s, depressions or even cyclones (for instance, ‘Vayu’) and underwriting monsoon onsets.

Typically, when the MJO is over the Maritime Continent at this time of year, there is a tendency for enhanced convection over the Bay, South China Sea, and parts of the Maritime Continent to the North of the Equator, the Bureau said.

This should provide the required environment for the brewing ‘low’ in the Bay to sustain itself, and pull in the rains over Central India and most of adjoining South Peninsula from later this week.

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