A likely super typhoon and a tropical depression in the North-West Pacific will combine to deliver an easterly ‘pulse’ into the Bay of Bengal to charge up the Indian monsoon from next week.

The ‘pulse’ being generated from the Taipei region is seen crossing Indochina and landing in the North Bay, where it could intensify as a likely depression.

This is in line with a forecast outlook from the US National Weather Services, and may be set into motion from September 14 to 18, when a rudimentary circulation may develop in the Bay.

During the subsequent week or so, it might intensify as a depression, and according to the US forecasts, head west-south-westwards to the Andhra Pradesh coast, where it may cross the coast.

The typhoon, named Mangkhut, has tracked westward over the West Pacific and is heading towards Hong Kong per initial indications, clocking wind speeds of 148 km/hr and gusting to 185 km/hr.

It is forecast to reach the East China Sea/North-West Pacific and likely to posit itself at a location over the waters equidistant from the northern tip of the Philippines and Taipei by September 15.

Both the Luzon region in North Philippines and Taiwan are expected to be affected by the roaring winds as Mangkhut scorches the intervening waters and heads for Hong Kong/South-East China.

Rainfall trend

Meanwhile, the tropical depression has already left Taiwan and is headed towards Hanoi in Vietnam, where it seen landing up as a low-pressure area by September 14, and weakening further.

But the depression would have prepared the ground for a much stronger typhoon Mangkhut to do what is needed to flare up the Indian monsoon in what is its end phase.

The India Met Department (IMD) has said that scattered to fairly widespread rainfall is likely over the Andaman & Nicobar Islands, East and North-East India in ite extended forecast from September 15 to 17.

Scattered rainfall is also likely over the western Himalayan region, Central India and adjoining Peninsular India while being isolated over the the rest of the country.

A 10-day outlook from the European Centre for Medium-Range Weather Forecast shows the East Coast of India lighting up as a rain band approaches the South Coastal Andhra Pradesh coast.

Monsoon weakening

Tamil Nadu, Interior Karnataka, Rayalaseema, Coastal Andhra Pradesh, Odisha, Chhattisgarh, Bihar, Jharkhand, and the North-Eastern States may receive varying amounts of rain during this period.

Heavy to very heavy rainfall is also indicated for the rugged terrain of Nepal, Bhutan and Arunachal Pradesh in India as well as parts of Bangladesh.

The IMD said that the rain-driving monsoon trough over North India has shifted further northwards towards the foothills.

This happens during the weak phase of the monsoon, when rains are confined to the foothills of the Himalayas, the East Coast, and Tamil Nadu and adjoining interior peninsula.

The IMD said that strong southerly/southeasterly winds carrying moisture from the Bay will prevail over the North-Eastern States of India until the day after tomorrow. Intense widespread rainfall may lash the hills of Bengal, Sikkim, Arunachal Pradesh, Assam and Meghalaya during the next four days and Nagaland, Manipur, Mizoram and Tripura for next three days.

PTI adds: The countrywide monsoon reading saw the highest rain deficit of the season in August — ironically the month when a large part of Kerala was submerged and many other states received “excess” rainfall, per official IMD data.

August saw 92 per cent of rainfall of the Long Period Average (LPA) after 95 per cent in June and 94 per cent in July, the India Meteorological Department (IMD) data showed.

IMD officials blamed the low nationwide figures largely on deficient rainfall in east and northeast India.

Officially, the Southwest Monsoon season runs from June to September. From September 15, it usually starts withdrawing from Rajasthan and ends gradually.

Overall, August received 241.4 mm of rainfall in comparison to the normal precipitation of 261.3 mm.

In its Long Range forecast for the rainfall during the second half (August —September) of the Southwest Monsoon 2018, the IMD had predicted that August would get 96 per cent of rainfall with an error margin of plus or minus 9 per cent.

The overall monsoon deficiency, as of today, stands at minus 7 per cent.

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