Rainy days are here again. It is going to rain for the next 100-plus days in the State. One needs to add umbrellas, raincoats, and water-resistant footwear to the list of daily-use products as the showers can leave one drenched anytime during the day. Highways to streets and side roads will soon resemble rivulets, with rainwater gushing through them.
Kerala is all set to renew its annual date with the southwest monsoon, the Edavapathi rain. The rain that hits the State in June is traditionally known as Edavappathi as the onset happens on Edavam 15, the second half of the month or June 1 by the English calendar, every year.
This year, the seasonal rain is likely to hit the Kerala shores during the middle of the Malayalam month Edavam, a few days behind schedule. Weathermen have predicted the monsoon showers will reach Kerala by June 4 or Edavam 21 by the Malayalam calendar, four days later than expected. These variations and deviations from the schedule are normal and part of the monsoon regime, note weather experts.
What would one call the rain the State is currently receiving, mostly during the evening hours? “These are pre-monsoon showers,” asserts a weather specialist.
The State gets its share of pre-monsoon showers till a few days before the onset, which will bring the much-awaited respite from the summer heat. These showers will be accompanied by thunder and lightning, he says.
Once the monsoon touches down the shores of Kerala, there will be a marked change in the rain and wind patterns. Westerlies, the wind that will blow across the State from the western side, will gather strength and bring with them the rain, he explains.
Since 2018, the perception of monsoon has changed forever for every Keralite. Every burst of thunder and heavy downpour flood the collective memory of the State with the fearsome memories of the deluge which they encountered during the two consecutive years. Every onset of monsoon sets alarm bells ringing for Keralite as they try to calm themselves by recounting the near-epic survival and re-emergence of the State from the deluge.
“The monsoon showers may not flood the State as they happened in 2018 and 2019. Yet, we need to be on alert as Kerala may experience extreme rainfall events,” says K. Santhosh, Director, Indian Meteorological Department (IMD), Thiruvananthapuram.
When can one confirm the onset of the monsoon?
Southwest monsoon normally sets in over Kerala around June 1. It advances northward, usually in surges, and covers the entire country around July 15, says a communication from the IMD.
The IMD will declare the onset of monsoon if “60% of the 14 weather stations” set up from Minicoy to Mangaluru “report rainfall of 2.5 mm or more for two consecutive days“ after May 10. The wind field and a few other parameters are also looked into before declaring the onset.
Current indications are that the onset may be delayed by four days. The delayed onset shall not be translated into a surplus or deficient rainfall. The late onset does not in any way signify the performance of monsoon in a year, explains a weather expert. When it rains less than half of the normal showers, it is a weak monsoon. Any rain over one-and-a-half times to four times the normal is denoted as an active monsoon in metrological parlance.
Mr. Santhosh says Kerala needs to be prepared to handle extreme weather events such as heavy spells of rain during both the southwest and northeast monsoons.
“Climate change is a reality. The impact of climate change is felt everywhere, and extreme weather events are considered the hallmark of climate change. There were recent reports of sudden and excessive rain in countries in the Gulf desert region. States such as Kerala are likely to see the vagaries of nature in the form of extreme weather events like extreme rain,” he cautions.
“It may not rain continuously throughout the four months of the southwest monsoon. There will be an active spell of rain followed by a weak one. One active spell may last up to ten days followed by a weak spell. The duration of the weak spell, marked by low rainfall activity, can be up to five days,” he explains.
Kerala needs to anticipate heavy rainfall events during the active phase and brace itself for meeting such eventualities. High-intensity rainfall may occur. Also, there is a possibility of gusty winds moving across the State and leaving a trail of destruction in its path.
Gusty winds that could last a few minutes may move across landscapes during the period. They will gather a speed of up to 50 km per hour in a few minutes and lose the velocity in no time. Yet, they possess the potential to wreck damage in their course with their wind speed, warns Mr. Santhosh.
The country needs to expect a near-normal rainy season this year, predicts the IMD. The southwest monsoon rainfall, which is spread over four months starting June, over the country is most likely to be normal and will be in the range of 96% to 104% of the long period average (LPA), it predicts.
The LPA of the seasonal rainfall over the country for the period 1971-2020 is 87 cm, notes the updated long-range forecast outlook for the 2023 southwest monsoon season.
Looking at the region-wise possible spread of rainfall, the department predicts that the southwest monsoon is most likely to be below normal over north-west India and normal over central India, north-east India, and south peninsular India, which also includes the States of Kerala, Mahe, Lakshadweep, Karnataka, Tamil Nadu, Puducherry, Telangana, and parts of Andhra Pradesh, especially Rayalaseema region.
S. Abhilash, Director, Advanced Centre for Atmospheric Radar Research, Cochin University of Science and Technology, feels that the onset can be delayed by around one week this time considering the weather factors that influence the process. Though Kerala may get scattered rain during the first week of June, the real onset could be delayed further.
There also exists the possibility of cyclones, as in the case of Cyclone Tauktae, which brought heavy rainfall and flashfloods to areas along the coast of Kerala and on Lakshadweep in 2021. One needs to expect at least a depression during the period if not a cyclone. The Arabian Sea is warmer by around 1.5°C, which could favour the formation of a cyclone or a depression. Kerala needs to be prepared for these weather events, says Dr. Abhilash.
Kerala needs to anticipate extreme rain events even after the second week of June when the monsoon reaches its full vigour along the west coast. The State may emerge unscathed from the El Nino factor, the unusual warming of surface waters in the eastern equatorial Pacific Ocean, which has almost been confirmed. However, it will leave its presence felt in other parts of the country, he says.
With the memories of the destruction and deaths the two floods had left in Kerala, the government has geared up monsoon preparedness across the State. Besides mobilising its personnel and machines, the State authorities have asked local bodies to review their preparedness. They have been asked to identify buildings that can be used as rehabilitation centres and stock machines to be used for emergency rescue missions. Trained personnel, including those in the Civil Defence Force and Apathamithra, will be integrated into the rescue teams.
The Kerala State Disaster Management Authority has updated and released the Orange Book of Disaster Management, which lays down guidelines for monsoon preparedness and disaster response. The document, which was first released in 2019 May, is annually revised and published every year on May 25.