'August deluge ' missing, rain deficit this year adds to Kerala's monsoon mystery

Many generations later, imagine someone randomly going through the south-west monsoon data for 2019 and 2020. It is certain she would miss the Dracula fangs of the rainy season in these two years.

On paper, 2019 monsoon (June-September) is a 'normal' rain year and 2020 will in all probability be considered a rain deficient year. In other words, generally pleasant seasons with their vampire souls nicely hidden.

Official data can be so deceptive that it can casually hide the sudden and terrifying form the monsoon had acquired for some fleeting days in August in these two years, just the way a smile would hide an individual's wickedness.

Where has the killer vanished?

In Idukki, where 63 poor plantation workers were swept away by a landslide on August 7, there is now a rainfall deficit of 20 per cent. Wayanad, which also saw shock spells in early August push its vulnerable mountain slopes over houses and farms, has by the end of August a rainfall deficit of 30 per cent.

Last year in Wayanad heavy rainfall had triggered innumerable landslides and washed away 17 people in Puthumala, and still the district ended up with a rainfall deficit of nearly 10 per cent.

Unique brutality of 2018

Truth is, the ferocity of the monsoon during August in 2019 and 2020 was almost the same as in the deluge year of 2018. In 2019, the intensity was even higher than 2018, and this year it was only marginally less.

What made 2018 particularly brutal was that the fury of the monsoon was spread almost evenly across the state. In 2019, it was limited to the northern districts, and in 2020, the suffering was mostly in Idukki, Wayanad and some central regions like Kottayam and Alappuzha.

There is yet another reason why Kerala did not swell up in 2019 and 2020 the way it did in 2018. The monsoon was weak during June and July of both these years, and according to the Indian Meteorological Department (IMD), there was a monsoon deficit of over 30 per cent in 2019 and over 20 per cent in 2020.

Whereas in 2018, there was an excess of monsoon rainfall in both June (24 per cent) and July (64 per cent). On top of this came the mighty cloudburst. Idukki alone had received 800 mm of rainfall in just three days in the middle of August in 2018.

Here is one more reason why short intense spells during the months of August in 2019 and 2020 did not prove as disastrous as in 2018: Lessons were learnt and dams were better managed this year and last.

Monsoon's August shift

Site of landslide in Munnar's Pettimudi
Site of landslide in Munnar's Pettimudi

Nonetheless, weather experts are worried about the south-west monsoon's August emphasis in Kerala.

This was first noticed in 2018, when the rainfall excess, according to the IMD, was 180 per cent in August. In the previous four August months, except in 2014, there was rainfall deficit; in 2015 and 2016 the deficit was 49 and 39 per cent respectively.

Still in 2018, the monsoon had a healthy run during June and July, too. These months also had heavy rains except that they were not as destructive as in August.

It was in the subsequent years, in 2019 and 2020, that the south-west monsoon demonstrated a tendency to ignore its traditional entry month of June and also July, the month it normally gathers strength.

“In both these years, the onset was upset by tropical cyclones. In 2019, it was Vayu and this year, it was Nisagra," said S Abhilash of Department of Atmospheric Sciences, CUSAT. "Cyclones are supposed to be absent during June. But in the last decade, cyclones have been found to play havoc with the normal monsoon pattern. However, it is still early to say that the August tilt is going to be the new norm,” he said.

Shockingly unpredictable

Puthumala
Last year in Wayanad heavy rainfall had triggered innumerable landslides and washed away 17 people in Puthumala, and still the district ended up with a rainfall deficit of nearly 10 percent.

Though there was crowding of rains in August during the last three years, the general monsoon pattern varied wildly for the three.

In 2018, there was 180 per cent excess rain in August but the intensity dropped precipitously in September, causing a deficit of 31 per cent that month.

In 2019, the monsoon, which had over 30 per cent deficit by the end of July, transformed into a normal monsoon with an excess of 13 per cent by the end of September. There was consistent rain during the last two months of the south-west season in 2019.

This year, the intense short spells between August 4 and 10 more than made up for the 25 per cent monsoon deficit at the beginning of August. But after the furious cloud crash between August 4 and 10, monsoon activity just stopped.

Now, except for Thiruvananthapuram, there is rainfall deficit in all other districts.

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