IMD retains outlook for monsoon onset over Kerala around June 4

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The Indian Meteorological Department (IMD) reiterated that the southwest monsoon may enter Kerala around June 4 (with a margin of plus or minus four days) and generate normal rainfall (between 96 to 104 percent of the long-period average) for the country as a whole.

In the process, it will experience a positive beneficial Indian Ocean Dipole (IOD) phase and ignore any negative El Niño effect brewing in the equatorial Pacific, although there is no direct cause-and-effect relationship.

1997 parallel drawing

Interacting with journalists at a virtual press conference, DS Pai, Head of the Environmental Research and Monitoring Cell and Numerical Weather Forecasting, IMD, drew a comparison with 1997 which saw one of the strongest El Niño events but was able to present a normal monsoon season thanks to a synchronized positive IOD.

Recently, in 2019, the record-breaking positive IOD not only achieved a record monsoon overflow (110 per cent), but extended to late October.

To break the deadlock in two days

IMD expects the monsoon, which is currently stalled along the Nicobar Islands and bordering the southern Andaman Sea and bordering the Bay of Southeast Bengal, will make further progress in the next couple of days.

Then, you see the flows across the equator getting stronger and potentially creating a favorable environment over the southeast Arabian Sea off Kerala to accelerate the onset of flows around June 4th.

The IMD indicated a developing cyclonic circulation over the North Andaman Sea over the next two days (The line of business had mentioned this development bringing rotation closer to the coast of Myanmar), which will help in enhancing the flows across the Gulf and help in increasing the advance of the monsoon through the Gulf waters in the next two days.

High probability of El Nino

Pai said IMD has assessed that there is a high 90 percent chance that an El Niño that is not friendly to the monsoon may develop and begin to affect the monsoon.

A positive IOD phase may also develop to neutralize the effect of the former. Precipitation during June is expected to be 96 percent for the country as a whole, but less than normal (92 percent) in northwest India.

Meanwhile, Friday morning, a super tornado Mawar Looming menacingly in the western Pacific Ocean, more than 6,000 kilometers from Kolkata, continued diving flows from the Gulf. It may maintain its position for two more days, but it cannot prevent an active westerly disturbance from affecting northwest India.

A related trough this (Friday) stretched from northern Pakistan across India to Bangladesh. Prior to the western disturbances, a cyclonic circulation had cast anchor over northern Pakistan.

Changeable weather in the north

From this circulation the trough extended to Bangladesh. These two systems are expected to move towards northwest India in the next couple of days, bringing weather fluctuations ranging from rain, thunderstorms, lightning, hail and high winds across the region.

They also opened up a basin from north to south from southeastern Madhya Pradesh to coastal Karnataka.

The original East-West Basin extends from the cyclonic circulation over northern Pakistan and bordering Punjab to eastern Bangladesh through Punjab, southern Haryana, southern Uttar Pradesh, southern Bihar and Jharkhand, and the cyclonic circulation over West Bengal.

North-South basin from southeastern Madhya Pradesh to coastal Karnataka through Vidarbha, Telangana and North Interior Karnataka. All of these areas may slip under cover of rain, thunderstorms, lightning, hail, and high winds.

Southwesterly winds in the Gulf

The original trough also maintained a steady and strong band from the southwestern regions of West Bengal, the northeastern states and Bangladesh despite the overwhelming influence of the super cyclone.

On Friday morning, satellite maps showed fog along the Himalayan foothills across northwest India and eastern India. It has caused raging weather in Ayodhya, Basti, Akbarpur, Sultanpur, Amithi and Chajang, Jalalpur and Belwar in eastern Uttar Pradesh and also over neighboring Nepal.

Cloud cover has also been observed over Kerala and the adjacent coast of Karnataka extending to Mangaluru.

Meanwhile, IMD said conditions are favorable for the monsoon to advance to some other parts of the southern Gulf, Andaman Sea and Andaman and Nicobar Islands over the next two days. A new western disturbance is expected in northwest India within the next 3-4 days.

Monsoon onset by 5th June

Western disturbances, cyclone offspring cycles, and intrusive basins must be cleared before the monsoons can enter the coast of Kerala.

The latest forecasts indicate that a favorable environment will emerge during the first five days of June, helping to accelerate the start around June 5th or so. A beta monsoon onset vortex may form over the southeastern Arabian Sea around that time, according to predictions from IMD’s numerical model.

short term outlook

In its short term outlook, the IMD sees light to moderate rain spreading over most places in northwest India with thunderstorms, lightning and occasional gusty winds along the hills and rain in many places over adjoining plains with thunderstorms, lightning, occasional gusts and storms till today (Friday).

Thunderstorms and strong winds of up to 40-50 km/h have been warned over Uttarakhand, Punjab, Haryana and northern Rajasthan.

eastern and northeastern India

Over northeastern India, light to moderate rain is likely to continue with somewhat thunderstorms, lightning and gusty winds over Assam, Meghalaya, Mizoram and Tripura over the next two days.

Heavy rains are expected in Assam, Meghalaya, Mizoram and Tripura on Friday.

Over eastern India, somewhat scattered light to moderate rain, thunderstorms, lightning and gusty winds are likely over West Bengal, Sikkim, Bihar and Jharkhand. Heavy rains are likely in the hills of West Bengal and Sikkim today (Friday).