Wind map of the Bay of Bengal, October 18

(RSMC)

As the southwest monsoon retreats from the top half of India’s mainland, the eastern coastal states will likely slip from the clutches of the seasonal rains straight into a cyclone’s grip this week. Over the weekend, as cyclonic circulation started to take shape over the Andaman Sea, some meteorologists began to warn about a possible “super cyclone” for the eastern coast of India.

However, the India Meteorological Department (IMD) quickly clarified the rumours and noted that it is too early to tell whether the system will likely intensify to severe conditions. Indeed, different models have continued to offer contrasting projections of its strength and the path of the potential storm.

Despite varied projections, one thing for sure is that Odisha, West Bengal, and Andhra Pradesh will likely witness very heavy rains and strong winds between October 23 and 27. On Tuesday, IMD confirmed the fresh low-pressure area (LPA) to form over the eastern Bay of Bengal in the next 48 hours and travel towards the Indian coast.

Models differ on projected path and intensity

As per the IMD, the disturbance is “very likely” to intensify into a depression by Saturday (October 22) and then into a cyclonic storm over western Bay of Bengal.

Both Global Forecast System (GFS) and the European ECMWF model agree that the storm will track more northwards and will remain weak with a peak intensity of 60-70 kmph. As per the latest projections by the ECMWF, the system will develop into a deep depression and make landfall near the Odisha-West Bengal border by Tuesday next week.

Initially, the GFS model projected that the system would strongly intensify into an ‘Extremely Severe Cyclonic Storm’ or a ‘Super Cyclonic Storm’ before landfall near the north Andhra Pradesh-Odisha coast. However, the updated projections from GFS on Tuesday suggest a landing area similar to that of ECMWF but slightly delayed. Moreover, the projected strength has also come down to just 65 kmph just before landing on West Bengal by around Tuesday night (October 25).

Potential Cyclone Sitrang

It is important to note that a disturbance is classified as a Cyclonic Storm only once it reaches over 60 kmph of intensity. As most projections have kept the possible peak strength of the current system at a borderline 60-70 kmph, the chances of it being characterised as a cyclone continue to remain uncertain.

However, if the storm intensifies into a cyclone, it will be named Sitrang. The name is based on a suggestion from Thailand in line with the World Meteorological Department’s (WMO) guidelines for naming tropical cyclones.

“IMD’s extended range forecast does point to a probable cyclogenesis developing into a depression after October 21. We aren’t ruling out the possibility of this system intensifying into a cyclone. But it’s too early to say how much it will intensify, as the circulation hasn’t formed yet,” said IMD chief Mrutyunjay Mohapatra to The Times of India.

Most forecasts suggest heavy rains and strong winds to the eastern coasts from Monday to Wednesday next week; therefore, residents are advised to remain updated. Odisha, Andhra Pradesh, and West Bengal have already been revelling in excess rains so far this month. Between October 1 and 17, Odisha and West Bengal garnered around 115 mm of rainfall, resulting in substantial excess of 36-50%. The coastal Andhra Pradesh and Yanam subdivision accumulated 187 mm of rains against their normal of 103 mm, which is a whopping 81% excess.

The cyclone season

This upcoming storm could be the first post-monsoon cyclone of this year, and the governments of eastern coastal states have already begun preparations for the same.

The Indian Ocean has a ‘year-round’ Cyclone Season. The tropical cyclone season in the northern Indian Ocean, which includes the Bay of Bengal and the Arabian Sea, is quite unusual, with two peaks — one from April to June and the second from September to December. The easter coastal states are familiar with strong weather systems during October-November, commonly known as the eastern coast’s cyclonic season.

The last cyclone over the Bay of Bengal was Cyclone Asani which killed three people and brought heavy downpours to Andhra Pradesh, Odisha and West Bengal. And while most cyclones tend to cause a lot of devastation, Asani was relatively polite, only bringing heavy rainfall and some respite from summer heat to the states along the East coast and across the southern peninsula. As 2022’s first cyclone, Asani intensified into a Severe Cyclonic Storm on May 8 but weakened quickly into a deep depression before landfall over Andhra Pradesh on May 11.

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