North-East monsoon may spring up more surprises

Close on the heels of directing non-seasonal rains into the West and North-West India, the ongoing North-East monsoon could be waiting to unfold more surprises for the West Coast during this week.

A core of the northeasterly winds that currently sustain the low-pressure area in the South-West Bay of Bengal could cross the peninsula and blow into the Arabian Sea to whip up a ‘low' there as well.

ARABIAN SEA SYSTEM

The US Navy's Fleet Numerical Meteorology and Oceanography Centre (FNMOC) saw these winds banding themselves akin to an ‘elephant's trunk' to gather winds and moisture around the Arabian Sea system.

In the process, the latter could strengthen a bit and be dragged in east for a likely tryst with the West Coast (Kerala-Karnataka).

What would likely prevent it from gathering further strength could be the less-than-desirable sea-surface temperatures in the South-East Arabian Sea (around Lakshadweep and the Kerala coasts).

RARE INSTANCE

If this scenario were to unfold, this would be a rare instance for Kerala to fancy its chances with a sea-based system of reasonable strength hurtling in straight towards its coast.

It would now be the turn for the Arabian Sea to give it back to the Bay; the system is shown as crossing the Karnataka coast and the larger peninsula to enter the Bay where it could likely interact with the remnant trough of the previous ‘low' and gain in strength.

The combined system will cut a path towards the Myanmar coast in due course, with some international agencies indicating that southerly-to-southwesterly winds (as against the seasonal northeasterlies) may help the system to rustle up some strength before hitting the Myanmar coast.

SILENT PERIOD?

In any case, all these activities are forecast to taper off around December 12, following which a ‘silent period' may descend on the Bay of Bengal and the Arabian Sea.

This will come about as winds change direction temporarily from being northeasterly to southerly-southwesterly to being even northwesterly, the FNMOC said.

Meanwhile, a weather update from India Meteorological Department (IMD) for the 24 hours ending Sunday morning said that widespread rainfall occurred over Andaman and Nicobar Islands.

It was fairly widespread over Tamil Nadu and isolated over Madhya Maharashtra, Coastal Andhra Pradesh and Kerala.

CONVECTIVE CLOUDS

Insat cloud imagery showed the presence of convective (rain-bearing) clouds over parts of Bay of Bengal, South Andaman Sea, Comorin area, South Arabian Sea, Orissa, South Chhattisgarh, Coastal Andhra Pradesh, South Interior Karnataka, Kerala and Tamil Nadu.

The belt of enhanced rains is forecast to migrate north-northeast along the East Coast with a weather alert from the IMD suggesting isolated heavy to very heavy rainfall over Coastal Andhra Pradesh on Monday and Tuesday.

The heavy to very rain alert would be valid for Rayalaseema and Tamil Nadu for Monday and subsequently for Orissa. The causative ‘low' in the South-West Bay persisted on Sunday; it is forecast to hold on its own for a couple of days more before weakening.

But this phase would only clear the way for the incoming system from the Arabian Sea to drop anchor in the Bay of Bengal and breathe life back into the remnant trough from the earlier ‘low.'

A short-term forecast by the IMD said that widespread rain or thundershowers would occur over Coastal Andhra Pradesh and fairly widespread over Rayalaseema, Tamil Nadu and Andaman and Nicobar Islands. However, it may decrease over Tamil Nadu after Monday.

Scattered rain or thundershowers would occur over Orissa, Telangana, South Interior Karnataka and Kerala. It may increase over Orissa and Telangana from Tuesday onwards.

Isolated rain or thundershowers have been forecast over Jharkhand, Gangetic West Bengal and Chhattisgarh on Monday and increase thereafter.

Fog to shallow fog conditions may occur over parts of the plains of North-West India mainly during morning hours until Wednesday.

Extended forecast until Friday said that scattered to fairly widespread rainfall activity may occur over East and adjoining Central and South Peninsular India. Mainly dry weather would prevail over plains of North-West and adjoining Central India.