Nov 30, 2024 – 1800 – Pondicherry

Writing this annual journal post on cyclone day feels special. for the very reason of constant rain as the BGM and occasional gust wind.

Fengal – the slow burner

Fengal got lot of attention because of the slow nature in terms of movement. Especially the reason being this. According to IMD, a typical cyclonic storm in the Bay of Bengal last about 4.4 days, while depressions have an average life span of 2.7 days. However, Fengal has defied the norm, and persisted for over five days and being a slower than usual. Same as the case for, speed at which it was moving. Fengal took five days to cover a mere 500 km, moving at a speed of just 5-6 kmph, which is the half the average speed typical weather disturbance in the region. The average speed of a weather system is 12-13 kmph. Basically it remained over the ocean more time than it should be. For that reason, Fengal was a unique cyclone that followed unique track compared to its ancestor in the past 50 years.

Stuck between ridges

Around 2130, there were updates that the cyclone could be stalled or stuck near the Cheyyur-Marakkanam coast. So what does this mean? How does it affect us?

The usual time the cyclone takes to cross is around 3 hours. Fengal was expected to take long or linger without crossing the inland fully. What should have been a 3 hour affair, was now going to take long time, leading to stalling near the coast. This will result in

1. steady impact throughout the night
2. localized flooding situation in the coastal area.

So what makes a cyclone to get stuck on the ocean? what prevents it from a landfall? The answer is “Ridge”. Ridges are invisible walls in the atmosphere with high pressure spread across different regions above the ocean. Cyclones, which are basically low pressure systems don’t like to smashed against the walls (ridge, in this case). So they tend to avoid them and move more like a river around the rock.

So why cant cyclone push through these walls (ridge)?

Cyclones use the winds to go around as a fuel for their motion. The winds are influenced by the pathways these ridges create. In our case, Fengal was trapped by these ridges and stalled in the same place for a while.

What a phenomenal it is to witness and experience. Cyclone being controlled by the invisible ridges (like walls) in the atmosphere and getting stuck between them, like how we get stuck in traffic jams.