Northeast monsoon outlook for India
By
Jason Nicholls, AccuWeather senior meteorologist
Updated Oct 21, 2021 6:40 PM EDT
The southwest monsoon finally began its withdrawal from far western portions of Rajasthan and Gujarat on 6 October and remained over the area on 7 October before advancing through Delhi on 8 October. That is against the normal withdrawal date of 17 September, so it is over two weeks late. This is the second latest withdrawal over the past 16 years with the latest start to the withdrawal coming on 9 October, 2019.
Even with the very late withdrawal of the southwest monsoon in 2019, the monsoon cleared all of India and the northeast monsoon began on 16 October, 2019. The one difference between 2019 and this season is that the Southern Oscillation Index (SOI) in September 2019 was strongly negative and this September it was strongly positive. A strong positive SOI usually correlates to a late onset of the northeast monsoon in southern India. The normal onset of the northeast monsoon is around 15 October.
Courtesy Queensland Government
We are expecting a late start to the northeast monsoon thanks in part to the strongly positive SOI in September. We are expecting the northeast monsoon to commence over southern India around 23 October, plus or minus four days. A monsoon low or possible tropical system can impact the eastern coast of India during this period as well.
So what is expected during this northeast monsoon season? First we will look at our analogs. Our top six analogs are on the left and all 11 referenced analogs are on the right. There is not a tremendous difference between the two packages, except our top analogs are much drier over Sri Lanka.
Taking a look at some model outlooks from the October through December period we see some good similarities between the various models and the analogs. The constants on the models and analogs are dryness in far northwest India and Sri Lanka with wet anomalies favored in Andhra Pradesh, Odisha, northern Tamil Nadu into Karnataka.
Now look at our outlook for the northeast monsoon. The forecast did not stray too far from model guidance and analogs due to a lack of strong teleconnection signals with the fading Indian Ocean Dipole and only a weak La Nina expected to develop partway through the season.
We are favoring near- to above-normal rainfall from West Bengal and Odisha to Andhra Pradesh, northern Tamil Nadu, Karnataka and northern Kerala. The areas where rainfall is expected to run below normal are the far southern tip of India into Sri Lanka, but these areas can receive better rainfall late in the season and perhaps carrying into January. The good rain in West Bengal, Odisha, Jharkhand and Bihar look to be favored early in the season with a trend toward dryness late in the season. Overall, India should have 98-103% of normal rainfall during the northeast monsoon.
The wildcard will remain tropical activity with the possibility of two or three tropical seasons in the Bay of Bengal, including the potential tropical threat late next week. There is also the chance for tropical development in the Arabian Sea over the next three months, but impacts on India from any Arabian Sea development may be limited.
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Weather Blogs / Global weather
Northeast monsoon outlook for India
By Jason Nicholls, AccuWeather senior meteorologist
Updated Oct 21, 2021 6:40 PM EDT
The southwest monsoon finally began its withdrawal from far western portions of Rajasthan and Gujarat on 6 October and remained over the area on 7 October before advancing through Delhi on 8 October. That is against the normal withdrawal date of 17 September, so it is over two weeks late. This is the second latest withdrawal over the past 16 years with the latest start to the withdrawal coming on 9 October, 2019.
Courtesy IMD
Even with the very late withdrawal of the southwest monsoon in 2019, the monsoon cleared all of India and the northeast monsoon began on 16 October, 2019. The one difference between 2019 and this season is that the Southern Oscillation Index (SOI) in September 2019 was strongly negative and this September it was strongly positive. A strong positive SOI usually correlates to a late onset of the northeast monsoon in southern India. The normal onset of the northeast monsoon is around 15 October.
Courtesy Queensland Government
We are expecting a late start to the northeast monsoon thanks in part to the strongly positive SOI in September. We are expecting the northeast monsoon to commence over southern India around 23 October, plus or minus four days. A monsoon low or possible tropical system can impact the eastern coast of India during this period as well.
So what is expected during this northeast monsoon season? First we will look at our analogs. Our top six analogs are on the left and all 11 referenced analogs are on the right. There is not a tremendous difference between the two packages, except our top analogs are much drier over Sri Lanka.
Taking a look at some model outlooks from the October through December period we see some good similarities between the various models and the analogs. The constants on the models and analogs are dryness in far northwest India and Sri Lanka with wet anomalies favored in Andhra Pradesh, Odisha, northern Tamil Nadu into Karnataka.
Now look at our outlook for the northeast monsoon. The forecast did not stray too far from model guidance and analogs due to a lack of strong teleconnection signals with the fading Indian Ocean Dipole and only a weak La Nina expected to develop partway through the season.
We are favoring near- to above-normal rainfall from West Bengal and Odisha to Andhra Pradesh, northern Tamil Nadu, Karnataka and northern Kerala. The areas where rainfall is expected to run below normal are the far southern tip of India into Sri Lanka, but these areas can receive better rainfall late in the season and perhaps carrying into January. The good rain in West Bengal, Odisha, Jharkhand and Bihar look to be favored early in the season with a trend toward dryness late in the season. Overall, India should have 98-103% of normal rainfall during the northeast monsoon.
The wildcard will remain tropical activity with the possibility of two or three tropical seasons in the Bay of Bengal, including the potential tropical threat late next week. There is also the chance for tropical development in the Arabian Sea over the next three months, but impacts on India from any Arabian Sea development may be limited.
Report a Typo