Explained: Why Cyclone Vayu is an obstacle to northward progress of monsoonhttps://indianexpress.com/article/explained/why-cyclone-vayu-is-an-obstacle-to-northward-progress-of-monsoon-5774170/

Explained: Why Cyclone Vayu is an obstacle to northward progress of monsoon

Vayu is much weaker than Fani. At its strongest, it is likely to generate winds of speed 110-120 km per hour, according to current forecasts. In contrast, winds associated with Fani had speeds of about 220 km per hour

Explained: Why Cyclone Vayu is an obstacle to northward progress of monsoon
The approaching Cyclone Vayu. (Source: US Joint Typhoon Warning Center)

Just over a month after the powerful cyclone Fani devastated large areas of Odisha, another cyclone is headed towards India, this time towards the Gujarat coast. Cyclone Vayu – it is still to develop into a cyclone and is only a deep depression as of now – is currently positioned around 250 km northwest of Aminidivi island in Lakshadweep and about 750 km southwest of Mumbai, and is slated to reach the Gujarat coast in two to three days.

Vayu is much weaker than Fani. At its strongest, it is likely to generate winds of speed 110-120 km per hour, according to current forecasts. In contrast, winds associated with Fani had speeds of about 220 km per hour. Vayu, even at its most powerful, therefore would only be categorised as a “severe cyclonic storm”, while Fani was an “extremely severe cyclonic storm” and almost satisfied the conditions for classification as a “super cyclone”.

Monsoon worries

While Vayu is unlikely to result in widespread destruction, it is a cause for concern for a different reason. It is likely to halt the northward progression of the monsoon for a few days. The arrival of the monsoon has already been delayed, hitting the Kerala coast on June 8 instead of June 1.

The cyclone is expected to interfere with normal progression, by sucking all the moisture from the monsoon winds towards itself. Cyclones are sustained by very strong low-pressure areas at their core. Winds in surrounding areas are forced to rush towards these low-pressure areas.

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Similar low-pressure areas, when they develop near or over land, are instrumental in pulling the monsoon winds over the country as well. But right now, the low-pressure area at the centre of the cyclone is far more powerful than any local system that can pull the monsoon winds moving northeast.

Follow LIVE updates on Cyclone Vayu

“We will see a brief hiatus in the monsoon progression because of the cyclone. The northward progress, especially in interior areas, would not be possible till the cyclone dissipates. The western coast would continue to have rains during this time, but interior parts would have to wait till two to three days after the cyclone dissipates,” said D Sivananda Pai, head of climate research and services at India Meteorological Department (IMD).

What this means is that the places where the monsoon has already reached would continue to get rain, mainly along the western coastline, but other areas would have to wait a little longer.

K Sathidevi of IMD told The Indian Express that according to current forecasts, Vayu was likely to touch the Gujarat coast somewhere near Veeraval and Diu either around midnight of June 12 or early morning of June 13. It is likely to dissipate very fast after that because the land and atmosphere in the area was devoid of any moisture that can sustain it any further. The northward progression of monsoon can be expected two to three days after that, Pai said.

Arabian Sea cyclones

Though cyclones are common in the June, very few of them originate in the Arabian Sea. Most of them are found in the Bay of Bengal. In the last 120 years for which records are available, just about 14% of all cyclonic storms, and 23% of severe cyclones, around India have occurred in the Arabian Sea. Arabian Sea cyclones are also relatively weak compared to those emerging in the Bay of Bengal.

This, along with the fact that the Gujarat coastline, which is where most of the cyclones emerging in the Arabian Sea are headed, is not very densely populated, ensures that the damage potential of the cyclones on the western coast is comparatively low.