Kerala State Disaster Management Authority has issued a string of red and orange alerts across the state during the first four days of the week given the formation of a low-pressure area over the Bay of Bengal around Thursday and its movement inland over Central and adjoining West India.

The Authority recalled the experience of during 2018 and 2019 – with the former witnessing the Great Flood of a century – and called residents of those areas identified by its own expert committee as well as those picked by the Geological Survey of India as vulnerable, to an enhanced state of alert.

Citing predictions of the India Meteorological Department (IMD), the Authority said that those places falling under the Orange alert could record rainfall of 11.5-20.4 cm during 24 hours while those under the Yellow alert category, between 6.5 cm and 11.5 cm during the same period.

Subject to change on the go

These are subject to upgrade/downgrade in line with the changes like alerts from the IMD.

Meanwhile, both Kerala and Coastal Karnataka enter August, the second rainiest of the four monsoon months, with some trepidation given their tryst with the month both in 2018 and 2019.

One saving grace is that most of the major reservoirs that got flooded over in 2018 in Kerala, adding to the misery, are filled to less than half of their capacities two years down the line. That may mean larger space to hold the inflows from a reviving monsoon but doesn’t rule out the threat of landslides.

All the more so because the last week has already witnessed heavy to very rain along some of the fragile reaches along the Ghats in the hilly districts where the slopes may have already got soaked. A couple of minor landslips have previously been reported in North Kerala last week.

Circulation on the way in

Meanwhile, the incoming cyclonic circulation from the South China Sea is navigating across Indochina on Sunday and is expected to glide its way over Laos and Myanmar over the next couple of days into the waiting hands of the Bay of Bengal, where it would intensify as a low-pressure area.

The Bay has looked more like a graveyard for low-pressure areas in the recent past, but the incoming circulation has already been able to make its presence felt across India’s West Coast and adjoining interior Peninsula by attracting monsoon flows and plotting a heavy to very heavy rain regime over the past week and more.

And this is forecast to intensify further as it develops as a low and crosses the Odisha-West Bengal and heads straight to the West across East India, Central India (Madhya Pradesh) and adjoining North-West India with what looks like meteoric speed before landing in the North-East Arabian Sea by August 8.

Zone of turbulence set

Giving details on how the atmosphere is readying to prepare for an enhanced monsoon phase, the IMD said that a shear zone of turbulence (where low-pressure areas embed) across Solapur, Hyderabad and Visakhapatnam, which will coexist with the active phase of the monsoon.

The monsoon trough over North India too has aligned with its normal position and will move further southwards to accelerate the weather transformation during the next 3-4 days. The net result would be strengthened flows over the Arabian Sea and along the West Coast, and intensification of the rainfall.

The monsoon will enter to active phase over the Central and Peninsular India from Tuesday and stay as such into the rest of the week. Widespread rainfall with scattered heavy to very heavy rainfall with isolated extremely heavy falls is likely over Konkan and Goa from Monday to Wednesday.

Heavy falls for Mumbai

Over Mumbai, the rainfall would be heavy to very heavy on Monday, and with isolated extremely heavy falls on Tuesday and Wednesday as well as over Madhya Maharashtra including the Ghat areas. Heavy to very heavy falls also very likely over Coastal Karnataka and Karnataka from Monday to Wednesday.

Widespread rainfall with heavy to very heavy rainfall at isolated places with isolated extremely heavy falls have been predicted over the coastal districts of Gujarat Wednesday and Thursday. The speed with which the low would have travelled would have left enough latent heat and momentum on its trail for another system to form over the Bay there the same day.

According to the projections of the IMD, it could likely mark a different course from here. It may dig a little southward to the North Andhra Pradesh coast from where it would cross land and orient itself towards West-North-West (unlike a straight line to the West in the previous case) and head to South Uttar Pradesh before being pushed by the westerlies to the Himalayan foothills.