Monsoon advances to Nicobar, South Andaman

Monsoon is normally expected to advance over the entire region around May 22 as per IMD’s dates for advance of monsoon to different parts of the country

Monsoon has advanced into some parts of southeast Bay of Bengal, Nicobar and South Andaman Islands around the expected time, India Meteorological Department (IMD) said on Friday.

Conditions are favourable for further advance of southwest monsoon into some more parts of south Bay of Bengal, Andaman Sea and Andaman & Nicobar Islands during next 3-4 days. (Representative Image/REUTERS)

Monsoon is normally expected to advance over the entire region around May 22 as per IMD’s dates for advance of monsoon to different parts of the country. “In association with persistence of south-westerly winds in the lower tropospheric levels and rainfall activity over the region during past 24-hours, southwest monsoon has advanced into some parts of Southeast Bay of Bengal, Nicobar Islands and South Andaman Sea on May 19,” IMD said on Friday.

“Monsoon enters the region around May 18 so it has advanced into Andaman and Nicobar region around the normal time,” said M Mohapatra, director general, IMD. Conditions are favourable for further advance of southwest monsoon into some more parts of south Bay of Bengal, Andaman Sea and Andaman & Nicobar Islands during next 3-4 days.

But IMD is also expecting western disturbances to impact the northern region during the next week. Western disturbances normally move to northern latitudes in summer and stop impacting the north-western region in May.

A western disturbance is impacting the Western Himalayan region. A cyclonic circulation is lying over east Uttar Pradesh and a trough is running from this circulation to North Interior Karnataka. A fresh western disturbance is likely to affect northwest India from May 23, IMD forecast on Friday.

Over northwest India, light/moderate scattered to fairly widespread rainfall with thunderstorm/lightning/gusty winds very likely over Uttar Pradesh and Rajasthan on May 22 and 23; Western Himalayan Region on May 23. Dust storm/dust raising winds are very likely in isolated pockets over Rajasthan on May 22 and 23. Under the influence of a fresh western disturbance, scattered to fairly widespread rainfall/thunderstorm likely over northwest India mainly during May 23 and 25.

“We are expecting a good rainfall spell due to an active western disturbance between May 23 and 25. The interesting things is there were only a few heat wave days in May. There were more heat wave days in April when it lasted between April 11 to 19 over eastern parts of the country. We have to see how monsoon progresses hereafter,” said RK Jenamani, senior scientist at IMD.

“Monsoon’s progress may be slow if western disturbances persist. An anti-cyclone or a sub-tropical high normally gets established north of Delhi during this time. During the monsoon season, western disturbances normally do not impact the Indian region except during monsoon breaks when they can interact with other systems. Western disturbances move to northern latitudes and a southwesterly wind pattern is established during monsoon season,” said M Rajeevan, former secretary, ministry of earth sciences.

Western disturbances are extratropical storms that originate in the Mediterranean region which bring sudden winter rain to the north-western parts of the Indian sub-continent. It is a non-monsoonal precipitation pattern which is driven by the westerlies according to IMD.

A bountiful monsoon is critical for the kharif (or monsoon) crop, to keep inflation under control, and to boost the rural economy. According to India’s agriculture ministry, 51% of India’s farmed area, accounting for 40% of production, is rain-fed, making the monsoon critical. With 47% of the country’s population dependent on agriculture for their livelihood (according to this year’s Economic Survey), a bountiful monsoon has a direct correlation with a healthy rural economy. For instance, Skymet said in a statement the expected sluggish advancement of the monsoon “may not augur well for kharif sowing.”

This year’s monsoon will also be closely watched because of the presence of an El Nino effect, a weather phenomenon that has a correlation with poor monsoons.

IMD has also predicted a “normal” monsoon at 96% (with an error margin of +/-5%) of the long period average or LPA. The LPA for the monsoon season between June to September is 87cm, which is calculated for the period of 1971 to 2020. Skymet Weather, however, has forecast “below normal” rainfall during the monsoon season.

Over northeast India, there is likely to be light/moderate widespread rainfall with thunderstorm/lightning/gusty winds very likely to continue over northeast India during next 2 days. Heavy rainfall is likely at isolated places over Assam and Meghalaya during May 19 to 23 and Nagaland, Manipur, Mizoram and Tripura on May 19. Over east India, light/moderate, isolated to scattered rainfall with thunderstorm/lightning/gusty winds are very likely over most parts of the region during the next 5 days. Heavy rainfall is likely at isolated places over Sub-Himalayan West Bengal and Sikkim on May 19, 20 and 23. Thundersquall (speed 50-60 kmph) with lightning is very likely at isolated places over Gangetic West Bengal and Odisha on May 19.

Over central India, light/moderate isolated light rainfall with thunderstorm/lightning/gusty winds (speed 40-50 kmph) over Chhattisgarh during next 5 days; over Vidarbha on May 22 and May 23. Over south India, light/moderate isolated light rainfall with thunderstorm/lightning/gusty winds is very likely over most parts of the region during next 5 days. Thunderstorm/lightning/gusty winds (speed 40-50 kmph) very likely over Coastal Andhra Pradesh, Yanam, Telangana and Rayalaseema on May 19.

On Thursday, maximum temperatures were in the range of 38-42 degree C over many parts of Rajasthan, Uttar Pradesh, Gujarat, Central, adjoining East India and North Peninsular India. Maximum temperatures are near normal/below normal in many parts of the country. On Thursday no significant heat wave conditions prevailed in any parts of the country. Heat wave conditions are likely in isolated pockets over south Uttar Pradesh during May 20 to 22; over West Rajasthan, north Madhya Pradesh on May 20 and 21 and over Chhattisgarh and Jharkhand during May 21 to 23. Due to humid air and high temperature, uncomfortable conditions are likely over Konkan region during next 5 days and over Andhra Pradesh, Tamil Nadu and Kerala on May 19 and 20.