Onset of the Northeast monsoon in Chennai can be delayed a week or perhaps more from its average October 20 start date, Nicholls added.
New Delhi:
The Southwest monsoon in India is forecast to begin its withdrawal through South Asia at a slower than average pace this season, a weather report said on Tuesday. This may delay the onset of the Northeast monsoon in southern India.
"We do not expect the withdrawal to begin in northwestern India until the week of September 6 or 13," AccuWeather Lead International Meteorologist Jason Nicholls said.
On average, the monsoon begins its retreat in northwestern India at the very start of September.
With the later withdrawal of the Southwest monsoon, the Northeast monsoon onset in southern India may be delayed until late October.
"Some of the rain from non-tropical systems will be excessive and can lead to flooding across Vietnam, Laos, Cambodia, Thailand, Myanmar, Indonesia and Malaysia," Nicholls said.
"Onset of the Northeast monsoon in Chennai can be delayed a week or perhaps more from its average October 20 start date," Nicholls added.
AccuWeather's team of international meteorologists expects a normal to above-normal monsoon season across much of southern India from October through December.
This Northeast monsoon brings a surge of rainfall to parts of eastern and southern India as dry air invades the main Asia continent. Far southern Tamil Nadu and Kerala and Sri Lanka could be drier than average due partially to the late onset of the monsoon.
"Sri Lanka may make up for rainfall deficits from October to December as the Northeast monsoon and associated wet weather may last into January," Nicholls said.
Tropical depressions or cyclonic storms are forecast for both basins of the northern part of the Indian Ocean this autumn.
"The wild card for rainfall in South Asia will be the threat from tropical systems," Nicholls said.
Long-term weather and sea surface conditions are predicted to favour more storms over the Bay of Bengal, but the Arabian Sea will be quite active this season, too.
"Steering winds may favour most storms in the Bay of Bengal to impact northeastern India and Bangladesh, but tracks into southern India cannot be ruled out," Nicholls said.
"Systems in the Arabian Sea could impact western India, but the favoured areas for impacts look to be toward the southern Arabian Peninsula."
Drier weather is forecast to return to the southern part of the Arabian Peninsula during November.
Much of the rest of the Middle East will be drier and warmer than average for the autumn as a whole.
Much of East Asia is forecast to have near-to above-normal temperatures during this autumn, but as is sometimes the case, late-season cold shots are forecast to spread southward from Siberia and into Mongolia and northeastern China.
Cold air is also forecast to settle into portions of Kazakhstan later in autumn.