With September 2021 turning out to be one of the wettest months in Odisha's history, all eyes are now on October. And as it is about to bow out, has, however, dropped enough hints on what is in store -storm, shine or rain - in the days to follow.
As per an analysis, the spurt in low pressure systems in succession has been partly attributed to increased weather disturbances in the west Pacific ocean. Nearly half of the monsoon lows formed in September has a west Pacific connection.
"West Pacific Typhoon activity was sobered and so also the absence of westward movement of their remnants into the Bay of Bengal, which had been the cause of less formation of LPS (low pressure system) over the Bay of Bengal in August," observed IMD report.
Stormy Autumn?
Since the stormy season in October is majorly linked to the withdrawal of monsoon, the moot point is when will monsoon exit from Odisha?
As per weather models, northwest India is going to measure some rainfall activities till Sept 28, all factors indicate nil rainfall from October 1. As a consequence, the withdrawal process of monsoon 2021 will commence from next month only. And data shows this year, the withdrawal from Odisha will be between Oct 12-19, though the normal withdrawal date in Odisha is believed to be around Oct 10-15 (means starts from western Odisha on Oct 10 and exits from Puri on Oct 15).
- In 2018, monsoon withdrew on October 5
- In 2019, monsoon exited from State on Oct 15
- In 2020, the withdrawal date was Oct 28.
A study of post-monsoon weather shows that the delayed the withdrawal was, the lesser the possibility of cyclone taking a hit on Odisha.
As per a weather analysis, cyclonegenesis usually takes place during a 30-day period post the withdrawal of monsoon. Studies show in the majority of years, cyclones formed before Oct 10, track towards Odisha and West Bengal. And charts the Andhra Pradesh way, if developed during the last week of October or in November.
At the same time, the progression towards Odisha is also linked to monsoon withdrawal.
Sample Study
- 1999: Odisha was hit by 2 cyclones - A severe cyclone on Oct 17 and a Super cyclone on Oct 29.
- 1999 monsoon withdrawal started on September 27 from Rajasthan, and from Odisha by Oct 12-15.
- 2013: August last week was dry. IMD declared withdrawal of monsoon from Rajasthan on Sept 9. But the active Bay of Bengal gave birth to 3 back to back low pressures, including one depression that crossed between Bhadrak - Balasore on and around Sept 19-21, and, thus had revived the monsoon. Cyclone Phailin hit Odisha on Oct 13.
- 2014: Monsoon withdrawal started on 23 rd Sept from Rajasthan. During the withdrawal period cyclone Hudhud formed and hit Andhra Pradesh coasts.
- 2018: Withdrawal commenced on Sept 28, and exited from central India by Oct 6. In the withdrawal phase, Cyclone Titli hit Odisha on Oct 11.
- 2019: Monsoon withdrew from Odisha on Oct 14. Nearly, after 20-days of withdrawal, cyclone Bulbul took shape and skirted Odisha to hit West Bengal.
The above study shows cyclones developed either during the withdrawal phase or within 30-days post withdrawal. History shows during the period of 1805 - 2020, only 5 cyclones hit Odisha in November. Maximum cyclones hit Odisha in October, followed by September 12-30.
The West Pacific Connection
Besides, link with monsoon withdrawal, cyclones in the bay have a west Pacific link. It has been observed that cyclones in the monsoon withdrawal phase develop around the Andaman seas. And the developed systems are remnants of weather disturbances in the west Pacific.
As per a recent forecast by IMD and other met models, the west Pacific has recorded below normal cyclonegenesis this year. If forecasts are to be believed, then the genesis potential will not be high in October. Currently, only one system is detected in the west Pacific ocean.
October predictions show an increase in weather disturbances, but not of higher intensity. The observation over the years is, only remnants of intense systems find their way to BoB.