Hot weather to continue this week

Hot weather to continue this week

Akshay Deoras 

No respite from the ongoing high temperatures

Blistering weather conditions continue to bake eastern, central and southern parts of India. Heatwaves and severe heatwaves have been reported in the states of Odisha, West Bengal, Jharkhand, Bihar, Chattisgarh, Maharashtra, Uttar Pradesh, Telangana and Andhra Pradesh in the past week. The strong heating has also spread in parts of Tamil Nadu and Karnataka. Maximum temperatures in a large area (see below image) were around 40°C between 17th and 23rd April 2016 (see below image). In addition to this, many areas witnessed maximum temperatures in the 40-45°C range but some parts of Telangana, Maharashtra, Odisha, Chattisgarh, West Bengal and Jharkhand witnessed above 45°C maximum temperatures. (Note that the map is a representative map and doesn't depict actual political boundaries). 

Though such a hot weather was anticipated , the maximum temperatures recorded at Titagarh (a town in Odisha) have surprised everyone. The normal maximum temperature in this region in the month of April is 42°C and in the last decade, highest maximum temperature of 45.5°C was recorded. But, these records have been heavily smashed by the recently recorded temperatures. On 22nd April, this town recorded maximum temperature of 47.5°C which on 23rd touched 48°C and on 24th touched 48.5°C (6°C above normal). This has broken the previous record (of highest maximum temperature in April) of 48.1°C which was set on 30th April 1999. In addition to this, previous similar temperature records have been broken at Ramagundam (Telangana) and Anantapur (Andhra Pradesh). These regions recorded maximum temperatures of 46.1°C and 44°C respectively on 21st April 2016. 

IMAGE 1: Representative map showing maximum temperatures between 17th and 23rd April 2016. 

Courtesy: CPC, NOAA

Below temperatures will give an idea of the degree of ongoing hot weather in India. 

Maximum temperatures recorded on 22nd April 

Ramagundam, Telangana: 46.1°C

Bramhapuri, Maharashtra:  46.0°C

Sundargarh, Odisha: 46.0°C

Angul, Odisha: 45.5°C

Bankura, West Bengal: 45.3°C

Nizamabad, Telangana: 45.1°C

Chandrapur, Maharashtra: 45.0 °C

Maximum temperatures recorded on 23 April 

Bankura: 46.7°C

Jamshedpur: 45.8°C

Baripada, Odisha: 45.3°C

Angul: 45.1°C

Midnapore: 45.0°C

Khammam, Telangana: 45.0°C

Nalgonda, Telangana: 45.0°C

Sambalpur: 45.0°C

Maximum temperatures recorded on 24th April 

Tirupathi: 45.7°C

Nalgonda: 45.2°C

Khammam: 45.0°C

Ramagundam: 45.0°C

Nellore: 44.6°C

Bokaro: 44.1°C

Bankura: 43.8°C

Giridhi, Jharkhand: 43°C (8C above normal)

Bhubanewshwar: 41.8°C (5C above normal)

Kolkata: 40.2°C

As per the news reports, more than 150 people have died in India (this year) due to the heat conditions. 50 persons in Telangana and more than 85 in Odisha reportedly have been killed due to the heat (official figures will be lesser than this). Deaths have also been reported from other states such as Andhra Pradesh, West Bengal and Maharashtra. A week ago, the death toll was around 130 (all India figure) and around 30 in Odisha. Thus, there seems to have been a tremendous increase in the number of deaths in Odisha. The authorities have advised the citizens of states like Odisha to stay indoors between 11am and 3PM to avoid heat related illness. Despite of this, the reports of heat related deaths are coming which mean either this advisory isn't being followed properly or there are more factors (such as lack of ventilated houses, protection for poor people on daily wages etc.) causing the heat related deaths. 

Hot weather to continue

Unfortunately, the dominance of hot and dry near surface north-westerly winds will continue in this week also. This means that there won't be any significant change in the maximum temperatures of Central and Eastern parts of India. As a result, heat wave and some severe heatwave conditions will likely continue in this week also. Plains of North India will be soon joining the list of high temperature regions. A gradual rise in the maximum temperatures is anticipated in these areas by the end of this week. 

Thus, in this week, maximum temperatures (on an average) at many places of West Bengal, Odisha, Jharkhand, Bihar, Vidarbha (Maharashtra), Uttar Pradesh, Chattisgarh, East Madhya Pradesh, Telangana and Andhra Pradesh will remain between 41°C and 46°C. By Saturday, 30th April 2016, following maximum temperatures can be expected: 

Kolkata: 41°C

However, southerly winds will dominate in this week in Southern and Central parts of West Bengal. As a result, the relative humidity will increase and the weather will become sultry. Heat index (the temperature that our body feels due to effect of relative humidity) between 45C and 50C can be anticipated in the city in this week. This will add to discomfort. 

Bankura, West Bengal: 45°C 

Gaya, Bihar: 44°C 

Patna: 43°C 

Ranchi: 41°C 

Daltonganj, Jharkhand: 44°C 

Chandrapur and Wardha: 45C

Nagpur: 44C

Lucknow: 43°C

Allahabad and Varanasi: 44°C 

Hyderabad: 43°C 

Bhubaneswar: 42°C 

Balasore: 40°C 

Raipur: 43°C

New Delhi: 42°C

Chandigarh: 37°C

Ludhiana and Amritsar: 38°C

If the weather models are to be believed, then scattered post-noon thundershowers can be expected in parts of Maharashtra, Telangana and Andhra Pradesh after mid-week (i.e 27th April). But this rainfall won't be that sufficient to give any significant and long lasting relief from the heat. That's why people living in the aforementioned states must follow precautions  to protect themselves from the heatwave. 

High temperatures and more heat waves this week

FROM THE BLOG EDITION: http://www.downtoearth.org.in/blog/high-temperatures-and-more-heatwaves-this-week-53616

PUBLISHED ON 18TH APRIL 2016

High temperatures and more heat waves this week

Akshay Deoras  

 @akshaydeoras

 | 

Monday 18 April 2016

Many areas will witness high temperatures. Will the heat action plans work? 

India's "killer" heat waves are back and have already claimed 130 lives this season, according to news reports. At least 30 have perished in Odisha and more than 100 have died in other states. With the onset of summer, maximum temperatures have started increasing. Unlike March-April 2015, people aren't getting much relief from high temperatures due to the absence of thunderstorms and rain. Temperatures in some areas have crossed 45°C. They have been consistently above normal in many areas of West Bengal, Odisha, Bihar, Jharkhand, Uttar Pradesh, Maharashtra, Telangana and Andhra Pradesh. Between mid-March and mid-April 2016, maximum temperatures (excluding northeastern states and Jammu and Kashmir) have been above normal by 2-4°C. The greatest impact of this has been in north-central and eastern India. 

 

Maximum temperature departure between mid-March and mid-April 2016. Scale and shading are in degree Celsius (Representative image courtesy: World Ag Weather)

Causes of heat waves 

We often think that high temperatures and hot winds mean heat waves but that's not so. Countries like the United States, the Netherlands, Denmark and England have their own definitions of a heat wave. India Meteorological Department (IMD) has also created proper definitions for heat waves in plains, hilly and coastal areas. For heat waves to be declared, the maximum temperature at a place in the plains or in the hilly regions must reach at least 40°C or 30°C respectively. If this happens and deviation of maximum temperature of that place from normal maximum temperature becomes 4.5°C to 6.4°C, then a heat wave is declared. If this departure becomes 6.5°C or above, then a severe heat wave is declared. Alternatively, a heat wave is declared if the maximum temperature equals 45°C or above and a severe heat wave is declared if the maximum temperature equals 47°C or above. For coastal areas, maximum temperatures need to be at least 37°C or above and their departure from normal must be above 4.5°C.  

Heat waves are India's regular "visitors" but they have caught everyone's attention in recent years due to their links with climate change. 

For heat waves to form, the weather in a region needs to be mostly clear. All you need is an inflow of dry and hot near surface winds for temperatures to rise. Often there is a stagnant high pressure in the atmosphere which causes such heat waves. Cloud cover (mainly dense cloud cover), thunderstorms/rain reduce the heating of the surface due to which temperatures don't soar too high and heat waves don't form. Such dry winds bring heat waves in coastal areas when the land-sea breeze weakens.  

At present, dry and hot near surface winds are blowing over the northern half of India (areas above the Tropic of Cancer) from west/northwest direction. As a result of this, many areas are witnessing dry and hot weather.  

Over the years, there has been a lot of research on heat waves and their connections with El Niño Southern Oscillation and global warming. Recently, J Ratnam and other scientists from JAMSTEC Japan, and M Rajeevan, secretary of Ministry of Earth Sciences, investigated the causes of Indian heat waves and published a paper titled "Anatomy of Indian heat waves". 

Using observational data for the period from March-June from 1982-2013 and statistical methods, they identified two types of heat waves in India—one over north-central India and second over coastal eastern India. They stated that heat waves in north and central India are associated with atmospheric blocking over the Atlantic Ocean. Heat waves in coastal eastern India are associated with the reduction of moisture (thunderstorms) in these areas. Winds from the west/northwest drive the moisture away and this also reduces the land-sea breeze, thereby increasing the temperature.  

Hot weather this week

 

Representative image showing expected temperatures on the afternoon of Thursday, April 21, 2016. Figures are temperatures in degree Celsius (Courtesy: TropicalTidbits.com)

 

There won't be any significant respite this week from the ongoing heat in many areas of India. Maximum temperatures are expected to increase by a couple of degrees in the eastern and central parts of India (yellow dotted circle areas in image 1). As a result, significantly high temperatures (mostly in the 41-46°C range) are anticipated in many areas of West Bengal, Odisha, Bihar, Jharkhand, Vidarbha (of Maharashtra) and Uttar Pradesh. It appears that the effect of these rising temperatures will be the highest in West Bengal as compared to the other states of India. Once again, heat waves to severe heat waves will be witnessed in the aforementioned states. The plains of North India too will witness hot weather this week.  

Following maximum temperatures are expected by Thursday, April 21, 2016:  

Kolkata: 43°C

Bankura (West Bengal): 45°C

Gaya (Bihar): 44°C

Patna: 43°C

Ranchi: 41°C

Daltonganj (Jharkhand): 44°C

Akola, Chandrapur, Wardha and Nagpur (Vidarbha): 45-46°C

Lucknow: 44°C

Allahabad and Varanasi: 45°C 

Hyderabad: 42-43°C 

Bhubaneswar: 42°C (possibly increasing after April 21) 

Balasore: 43°C (maximum temperatures are already above normal by 8°C) 

Need for indigenous heat action plans 

In India, more than 3,000 people were killed during the heat wave of 2003, whereas more than 2,000 people lost their lives during the 1998 heat wave. At least 1,300 deaths were reported during the heat wave of 1988, whereas more than 2,000 people were killed during the heat wave in 2015. All these years were either El Niño years or the years following an El Niño event.  

Until 2015, techniques of forecasting and detecting heat waves weren't up to the mark. Also, there wasn't any proper coordination between the weather department, state governments, municipal corporations and hospitals. As a result, proper plans for dealing with heat waves weren't devised. Having recognised this gap, IMD issued the first-of-its-kind seasonal outlook for the summer. They have also started issuing extended range forecast of heat waves using advanced climate prediction system developed at Indian Institute of Tropical Meteorology, Pune. Heat action plans have been implemented in Ahmedabad, Nagpur and Bhubaneswar. But will these measures succeed in keeping the mortality rate low?  

The good thing about such heat action plans is that they increase the coordination between government agencies and the weather department which leaves the hospitals and administration better prepared to handle heat-related illness. But the measures suggested by these plans aren't that viable (in the context of India) and they don't address other local issues which are very important.   

The best way of avoiding heat strokes is to stay indoors (properly ventilated and cooled spaces), wear light clothes and keep oneself hydrated. But can the working class and poor people manage to follow this advisory? A large percentage of India's population still survives on daily wages. In drought-hit areas such as Vidarbha and Marathwada, MGNREGA is the main source of income. If these people don't go out to work, their survival will become difficult. Even the odd-even scheme in Delhi requires a large number of volunteers to stand in the sun for long hours.  

Heat-related illness can also occur by staying indoors. Every city has houses and slums which have poor or no ventilation, causing death due to high temperatures and suffocation. Young children and senior citizens are especially vulnerable. These action plans don't emphasise developing paramedical services but only promote some dos and don'ts.  

Thus, the western world model, though good, can't work as efficiently in India. There is a strong need to develop indigenous heat action plans to address the problem.

The little-known aspects of above normal monsoon forecast

From the blog edition: http://www.downtoearth.org.in/blog/the-little-known-aspects-of-above-normal-monsoon-forecast-53552

Akshay Deoras  

 @akshaydeoras

 | 

Wednesday 13 April 2016

A look at the changing methodology of long-term monsoon forecasting and what it means for drought in reality 

A couple on a monsoon day in Bengaluru Credit: Wikimedia Commons

 

The India Meteorological Department (IMD) issued the much-awaited first stage of the Long Range Forecast (LRF) of 2016's south-west monsoon on April 12. This came as a surprise to many as in the recent era, IMD has issued most of the LRF after April 20. The date of issuing of LRF used to be well-known in advance through news and IMD's press releases but this time, it all happened in a jiffy. Although there have been some instances when IMD issued the forecast before April 20 (such as in the year 2004), they never issued any LRF beforeApril 15 in recent years. No reason was stated for this "hurry" but a fact that can't be overlooked is that this year, many private monsoon forecasters and firms have already issued their own monsoon forecasts. There was a sort of competition as to who would issue the forecast first. 

 

Hopes of a normal south-west monsoon rainfall this year had been there for a while but the forecast of "above normal" rainfall came as another surprise from IMD. They expect this year's June-September rainfall to be 106 per cent (± 5 per cent) of 89 cm (which is India's mean south-west monsoon rainfall). In terms of probabilities, there is 34 per cent probability that the rainfall will be 104-110 per cent of 89 cm, 30 per cent probability that it will be greater than 110 per cent or 96-104 per cent of 89 cm. There is 5 per cent probability of it being between 90 and 96 per cent of 89 cm and only 1 per cent probability of being less than 90 per cent of 89 cm. 

 

This year's LRF happens to be the highest monsoon forecast (in terms of forecasted rainfall figure) IMD has issued in 17 years! In 1999, they had forecasted 108 per cent of the average rainfall. 

 

So, what must have led to a forecast of such a high figure?

 

The ongoing El Niño in the equatorial Pacific Ocean is set to "die" in this year leading to a transition to neutral conditions. Spring is generally a season of transitions not only in terms of weather (like winter to summer) but also for phases of El Niño Southern Oscillation (ENSO) i.e. El Niño, La Niña and Neutral. A decaying El Niño can give way to neutral conditions which in turn can give way to La Niña conditions. In some cases, there have been a return of El Niño conditions like 1952-53, 1957-58 etc. As a result of these transitions, the models predicting El Niño or La Niña (i.e the ENSO) have limited skills during the spring and aren't that reliable. This is famously known as the Spring Predictability Barrier. 

 

In India, we have more than 100 years of monsoon observations but ENSO-related observations are available mostly from 1950. Since 1950, there have been about 18 years or cases in which El Niño has transitioned to neutral or La Niña. For example, El Niño which started in 2009, ended in early 2010 and then gave way to neutral conditions followed by La Niña in the later part of 2010. In 12 out of 18 cases, monsoon rainfall has been above 100 per cent of 89 cm. Below is a list of these years in which recorded rainfall was more than 100 per cent. Note: figures in the brackets represent recorded rainfall in that year as per cent of normal. 

 

1959 (114 per cent), 1964 (110 per cent), 1970 (112 per cent), 1973 (108 per cent), 1977 (104 per cent), 1978 (109 per cent), 1980 (104 per cent), 1983 (113 per cent), 1988 (119 per cent), 2003 (102 per cent),  2007 (106 per cent) and 2010 (102 per cent). But in 6 cases, it has been below 100 per cent : 1952 (93 per cent), 1966 (87 per cent), 1992 (92 per cent), 1995 (97 per cent), 1998 (99 per cent) and 2005 (99 per cent). Plus, India hasn't seen any three consecutive years of drought. 

 

Thus, if one considers these factors and gives importance only to ENSO, a forecast of above 100 per cent rainfall can be easily given. Practically anyone can bet on a good monsoon using the undependable ENSO models. In fact, this is just the technique many private forecasters and firms have used to forecast this year's monsoon! 

 

Too much focus on ENSO? 

 

Since 1886, IMD has been issuing LRF for the monsoon and for operational purposes, and have been relying on statistical models. The monsoon is influenced by various atmospheric and oceanic factors at regional and global levels. All these factors influence the monsoon in their own styles. The first step in developing a statistical model is to find out such factors and also how much they have influenced the monsoon in the past. These factors are called as the parameters of the model. A mathematical equation is figured out thus establishing the relations between these parameters. If we know the values of these parameters (for example how warm the Pacific Ocean would be in the coming months) then we can get the answer of that equation which is the forecasted monsoon rainfall. 

 

The relation between these parameters and the monsoon rainfall keeps on changing over the years and hence IMD keeps on making changes in their model so as to maintain the accuracy. Between 1988 and 2002, IMD used the 16 parameter (such as temperature, pressure, snow cover etc.) method developed by Dr Vasant Gowarikar and his colleagues. In 2003, IMD made serious changes in this method by removing 10 out of 16 parameters and adding 4 new. This model was used to make a forecast till 2006 but in 2007, it was modified once again. Parameters and statistical techniques used in it were revised. But from 2007, the basic model has been the same (except for minor changes in 2014). 

 

The LRF which IMD issued on Tuesday, April 12 is supposed to be based on five parameters: 1) Difference in Sea Surface Temperature (SST) between North Atlantic and North Pacific Ocean 2) SST in equatorial South Indian Ocean 3) East Asia mean sea level pressure 4) Northwest Europe Land Surface Air Temperature 5) Equatorial Pacific Warm Water Volume (related to ENSO). But LRFs since 2007 talk only about the sea surface temperature conditions in the Pacific and Indian Oceans. LRFs always have this line—"As the sea surface temperature conditions over the Pacific and Indian Oceans particularly the ENSO conditions over the Pacific (El Nino or La Nina) are known to have strong influence on the Indian summer monsoon, IMD is carefully monitoring the sea surface conditions over the Pacific and the Indian oceans'.

 

But what about the other parameters? The parameter such as East Asia pressure is known to have more correlation with the monsoon (correlation coefficient of 0.61 in 1983-2002). Expressing concerns over the increasing focus on ENSO in monsoon forecasting, Dr. Ranjan Kelkar, former Director General of IMD said, "It's really odd to see the good old 16 parameter method coming down to just one i.e ENSO". He further said, "It is improper to overlook the role of other parameters in any kind of long term monsoon forecasting". 

 

Perhaps ENSO data is easily available and easy to understand. That's why there has been a lot of focus on ENSO! 

 

Does 106 per cent rainfall guarantee an end of drought in India? 

 

 

IMAGE: Rainfall anomaly during the south-west monsoon of 2004. Red colour indicates areas of poor rainfall. 

Courtesy: Monsoon on Line, IITM

 

Certainly not! The environment in India has become a kind of "Hip hip hooray!!" after the announcement of this above normal monsoon forecast. The way this forecast is being carried in the news is as if all the states in India (including the drought-hit states) are surely going to get above normal rainfall. Some have even started predicting an end to drought in the whole of India because of this forecast. 

 

Large scale rainfall scenario in India will be good if it rains as per the forecast. The chances of filling up of major dams of the nation will be better this year as compared to last year. Chances of an increase in overall agricultural production too will be better this year and hence a good thing for the economy. But the figure of 106 per cent (which represents entire India's average) doesn't give any clear idea of how much it will rain on subdivisional or districts levels of India. 

 

An interesting aspect of the south-west monsoon is its variability on various scales. On an all-India level, the south-west monsoon is less variable (variation from mean is just 10 per cent) but on subdivisional or district levels, its variability is large. If we take a look at various LRFs the IMD has issued since 2003, then it becomes clear that inspite of normal or above normal monsoon forecasts, there have been cases of below normal rainfall in many parts of India. In April 2003, IMD forecasted rainfall of 96 per cent of 89 cm but parts of Kerala, Tamil Nadu, Marathwada and Karnataka got a rainfall anomaly of 10 to 30 per cent. In 2004 and 2007, they forecasted 100 per cent and 95 per cent of 89 cm respectively but North India got very poor rainfall. The same year, parts of Central India received a rainfall anomaly of 10 to 20 per cent. In 2013, they forecasted 98 per cent of 89 cm rainfall but Northeast India got very poor rainfall. 

 

The monsoon's variability on monthly scales is also a mater of concern. Last year, Marathwada got normal rainfall in June, scanty rainfall in July, deficient rainfall in August but again normal rainfall in September. The net rainfall was however was deficient. Many states of India are witnessing drought. In many areas like Marathwada, Bundelkhand etc. it is no longer just a meteorological drought but a socio-economic drought. For drought to end completely i.e return of prosperity in the agriculture sector, sufficient recharging of ground water and return of socio-economic prosperity, all these places need excess and well-distributed rainfall not just this year but next year also. Proper techniques related to water harvesting, recycling of waste water and wise use of water will be important factors in determining how quickly the drought will end. 

 

There is no doubt that normal or above normal rainfall will mitigate the drought but as it has intensified so much, the forecasted rain might not be sufficient enough to end it completely. Thus, at this juncture, it will be important for farmers, the respective state governments and the Central government not to get carried away with the above normal monsoon forecast. There is a need to continue drought mitigation efforts and pragmatically plan things keeping in mind the climate and not just the monsoon forecast for that region.