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Monsoon: June 2012

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TOI has bad news at the end of the first month of the monsoons:

The monsoon entered its second month carrying a big rain deficit of 31%, as on July 1, with Met officials still hopeful of good rains in July and August. The next few weeks are crucial as the monsoon’s performance in this period could dictate whether the government would need to respond with special measures.

India Meteorological Department officials, who till last week were confident that the monsoon would pick up and end the month with a deficiency of only around 15%, said a recovery is expected within days as favourable conditions develop in both Arabian Sea and Bay of Bengal.

The monsoon line, currently passing through Veraval, Malegaon, Jabalpur, Varanasi and Gorakhpur, has not moved for around a week.

We all know that the monsoon has various effects at different locations. Although there is an overall deficit, Assam has the worst floods in 8 years. Kangla reported:

In Assam, the flood situation in Goalpara and Dhubri district continues to be grim though water level of the Brahmaputra and its a few tributaries receded.

The flood condition in Dhemaji, Jorhat,Lakhimpur, Dibrugarh, and Tinsukia has slightly improved.

State Health minister on Saturday said that Prime Minister Dr. Manmohan Singh and UPA Chairperson Sonia Gandhi are likely to visit the state on Monday to take a stock of the situation.

Rescue and relief operations are being carried out in the flood affected areas.

3 lakh 12 thousand people have been sheltered at around 550 camps.

Many villagers have also taken shelter at high embankments. But they are likely to leave the relief camps as condition improved slightly in Upper Assam.

Health department deputed around 200 medical teams along with Mobile Medical Unit.

Tube wells have been installed at relief camps.

Everyone is also familiar with the notion that rains are always intermittent. Just at it rains differently in different places, there are differing amounts of rains on different days during the monsoon. A report in Deccan Herald reports that we are in the middle of a break in the monsoon currently:

As the south west monsoon enters a break period threatening states with rain shortage, weather scientists admit they cannot forecast the duration of the break as physical processes underlying monsoon’s variability are poorly understood.

“Causes of the break period are not known. We also cannot say with certainty how long it will last. The breaks can happen due to anything from temperature variability in April to appearance of typhoons in north west Pacific, which has adverse relations with Indian monsoon,” a seasoned weather forecaster told Deccan Herald.

An analysis of half a century of India’s monsoon data by researchers from the Indian Meteorological Department (IMD) and the Indian Institute of Science suggest that in almost one-third of cases, the break period lasts between 7 and 10 days. Only in 40 per cent cases it is of 4 days duration. Also occurrence of the break period is quite common in July and August as well.

An editorial in the Hindu takes forward this new sophistication in discussions on the weather by, very unusually for a mainstream publication, discussing variability and probabilities:

Rainfall data for the past 140 years shows that even with a June deficit of that magnitude or greater, there is still a 60 per cent chance of the monsoon turning into a ‘normal’ one where nationwide rainfall for the season falls between 90 per cent and 110 per cent of the long-period average. The government, which has been pinning its hopes on a good monsoon to help propel economic growth, will undoubtedly be hoping for such an outcome. Even if the monsoon does turn out to be ‘normal,’ it is likely the rains will be at the lower end of that range. The probabilistic forecast in the India Meteorological Department’s updated monsoon prediction issued in late June has indicated that this is just what could happen. The forecast divides the traditional ‘normal’ range into three — ‘below normal’ (90 per cent to 96 per cent), ‘normal’ (96 per cent to 104 per cent) and ‘above normal’ (104 per cent to 110 per cent). The current monsoon has, according to the IMD, a 35 per cent chance of becoming ‘below normal,’ which is twice the climatological probability based on the outcome in past years.

Much could depend on what happens in the Pacific Ocean. The temperature at the surface of its central and eastern tropical waters has risen. The worry is that the temperature rise might continue and result in an El Niño, which could adversely affect the monsoon. According to the IMD statistics, there have been 36 El Niño years since 1875. Of these, the nationwide monsoon rainfall was between 90 per cent and 100 per cent of the long-period average in 14 years and above 100 per cent in six years, including in 1997 that saw one of the strongest El Niños of the last century. But there were ‘deficient’ monsoons, with nationwide rainfall falling below 90 per cent, in 16 El Niño years.

Bottom line? At this time it is equally likely that the monsoon will be normal or deficient. However, there seems to be very little chance of the monsoon this year being above normal.

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Written by Arhopala Bazaloides

July 2, 2012 at 4:39 am

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