Cyclonic circulation may impact monsoon onset over Kerala

Westerly winds over south Arabian Sea are currently seen continuing to prevail up to 2.1 km above the mean sea level, which is a favourable condition for southwest monsoon to set in over Kerala. 

However, formation of a cyclonic circulation over southeast Arabian Sea may critically affect the advancement of southwest monsoon towards Kerala coast, India Meteorological Department (IMD) said. 

“In view of a cyclonic circulation formed over southeast Arabian Sea, the cloud mass now more organized and concentrated over the same area, there has been some reduction of clouds off Kerala coasts in last 24 hours. Under the influence of this cyclonic circulation, a low-pressure area is likely to form over the same region during the next 24 hours, which is likely to move nearly northwards and intensify into a depression over southeast and adjoining east central Arabian Sea during subsequent two days. Due to formation and intensification of this system and its near north-ward movement likely to influence critically advance of southwest monsoon towards Kerala coast,” IMD said in its daily monsoon update. 

According to IMD’s first monsoon forecast in early May, the onset over Kerala is likely to be on 4 June with an error margin of four days. The Southwest monsoon that typically sets in over Kerala on 1 June missed its onset date on Sunday.

The crucial southwest monsoon starts its journey into the Indian subcontinent from the Kerala coast around 1 June with a standard deviation of about seven days. Monsoon rainfall is critical for agriculture production, with 52% of the net cultivated area relying on it. It is also crucial for the replenishing of reservoirs critical for drinking water apart from power generation across the country. The agricultural sector accounts for about 18% of the economy and is the largest employer.

The weather department has predicted a normal rainfall during this season despite the evolving El Nino conditions. Northwest India is expected to see normal to below normal rainfall. East and northeast, central, and south peninsula are expected to receive normal rainfall at 94-106% of the long-period average of 87 centimetres.

Rainfall between 96 and 104% of a 50-year average of 87 cm is considered ‘normal’.

The weather bureau is continuously monitoring the progress of monsoon arrival and will provide further updates on monsoon and the new weather system, it said.

“We have already crossed the normal onset date of monsoon over Kerala. Pre-monsoon rains have already started over Kerala, interior Tamil Nadu, and South Karnataka. Rain activities over Kerala may intensify further marking the onset of monsoon in the next twodays,” private forecaster Skymet said. “Monsoon onset will not have a thumping start over Kerala due to formation of a low-pressure area over Southeast Arabian Sea around June 6 or 7 and will gradually intensify into a depression. The weather system over the Arabian Sea will restrict the flow of south-westerly winds over the Indian mainland. These south-westerly winds are responsible for the further progress of monsoon over the interior Peninsula,” Skymet informed.

Skymet has forecast southwest monsoon to set in over Kerala coast on 7 June with an error margin of 3 days.

“There are currently three favourable conditions for monsoon onset over Kerala. However, things will be clear after 48 hours,” Mahesh Palawat, vice president Meteorology And climate Change at Skymet told Mint. After the onset over Kerala, monsoon may continue in the border areas of Karnataka and Maharashtra. However, the arrival of monsoon in South Peninsular and Central India is seen to be delayed by 8-10 days.”

If monsoon is delayed, farmers in Maharashtra, Madhya Pradesh and Gujarat may go sowing kharif crops late. Maharashtra grows Soybean, Tur (arhar), Urad (black gram), Groundnut, Maize (corn) and sugarcane in the kharif season, while Madhya Pradesh and Gujarat cultivate rice, soybean, jowar, maize, groundnuts, tur and urad.

Predicting arrival of monsoon in northwest India right now is difficult as the southwest monsoon has not made its onset over Kerala yet, Palawat said.