Southwest Monsoon 2019 withdrawal and North east monsoon Onset

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Southwest monsoon 2019 (SWM 2019) saw an active July and still seeing an active August. Thanks to  good rains in both these (crucial) months, overall monsoon rainfall now stands at +1%. This is good news since overall SWM 2019 season seems to be tending towards NORMAL. There are drought hit districts, due to the erratic nature of monsoon, but that discussion is for some other day.

SWM 2019 withdrawal to start around September 10, 2019

Normal date for monsoon withdrawal from northern most point of India is September 1st. This date holds true if there are no major western disturbances that form late August or early September. 

As I write this blog, North India is expected to receive good rains for the next few days (upto Aug 19) under the influence of monsoon axis, low pressure system, and western disturbance. Looking at the forecast, it seem like weak Western Disturbance is likely to form end of August. If this happens, monsoon withdrawal would be delayed by 1 week. Expecting withdrawal around September 9-10.

This means withdrawal from Mumbai would happen around September 22nd (delayed by a week). Further, full withdrawal from Indian subcontinent is likely to happen by October 10th, 2019.

Northeast monsoon ONSET to happen around October 22nd, 2019

The NEM 2019 onset likely to occur around October 22nd.

Performance of North east monsoon 2019 (NEM 2019) to be sub-par but better than 2018

Given that ElNino threat has faded, and Indian Ocean Dipole (IOD) conditions are favourable, NEM 2019 should get a boost. But I feel there is one important factor, which is - status of Bay of Bengal in October 2019 - that will govern NEM. 

Due to heavy river runoff, the Bay of Bengal branch will become highly stratified, which has the tendency to offset +IOD conditions. Therefore, I expect the IOD to become neutral from October beginning.

Under neutral IOD conditions, Northeast monsoon generally is a bit sluggish. 

Hence, I expect that performance of NEM 2019 would be slightly below normal, but much better than 2018 NEM season. 

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Disclaimer: The content given here are all personal views and the author will not be held responsible or held liable for any oversight or misinterpretation.

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