Tuesday, August 04, 2009
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Mercury up as weak monsoon extends to more areas
The weak monsoon phase became entrenched in more parts of the country with Gangetic West Bengal alone reporting meaningful rain coverage during the 24 hours ending Monday morning.
The monsoon trough lay parked along an alignment straddling the Himalayan foothills with monsoon westerlies finding their way into the west Pacific, a steaming cauldron away to the east.
PACIFIC CONVECTION
The Noida-based National Centre for Medium Range Weather Forecasting termed it a 'weak monsoon phase' that could last for another four to five days.
In between, a westerly trough is forecast to arrive over east India and even nudge a resident cyclonic circulation over Gangetic West Bengal into some activity.
But it would soon get sucked into the larger trough thrown up by the west Pacific systems, getting weakened in the process. A remnant circulation may potter around the Head Bay before rolling into the Andhra Pradesh coast.
The US Naval Research Lab at Monterey picked at least three areas of convection in the west Pacific, with model predictions favouring two of them to spin up as typhoons.
The feverish convection activity may weaken after August 10 only, according to European Centre for Medium-Range Weather Forecasts.
Some models indicated that the equatorial Indian Ocean may witness enhanced convection after August 10, apparently under the effect of a helpful Madden-Julian Oscillation (MJO) wave transiting to the east.
SOUTHERLY GAINS
The Climate Prediction Centre of the US National Weather Services sees extreme south peninsula getting some rain in the process but leaving the north of the peninsula high and dry.
A trail of moisture would still lead into the west Pacific, where convection and storm-building may start winding down around that time. No major gain is indicated for the Bay of Bengal during this phase according to available forecasts.
The Global Forecasting System model indicated that the westerlies flowing into the west Pacific would maintain their intensity until August 11.
They may weaken a bit after the enhanced convection there lets off some steam, but would still be headed into the west Pacific in the likely absence of a circulation in the Bay, around which they can rally.
MERCURY UP
Meanwhile, India Met Department said that day temperatures have started rising to beyond 40 degree Celsius in northwest Rajasthan, south Haryana and coastal Andhra Pradesh.
A prevailing upper air cyclonic circulation has been sustaining overnight rainfall in Gangetic West Bengal. The system is expected to hang around there for a while, according to model forecasts.
Fairly widespread rain with isolated heavy falls is likely over the north-eastern States during the next four days and over West Bengal, Sikkim and Bihar over the next three days.
A warning valid for the next two days spoke about the possibility of isolated heavy rainfall over the North-east, West Bengal, Sikkim, north Bihar, north Orissa and the Andaman and Nicobar Islands.
The following three days (August 6 to 8) would see fairly widespread to widespread rainfall activity over the North-east, adjoining east India and along the foot hills of Himalayas.
Towards the south, rain or thundershowers are likely at a few places over coastal and south interior Karnataka.
Isolated rain or thundershowers are likely over Tamil Nadu, Puducherry, Kerala, Lakshadweep, Andhra Pradesh and north interior Karnataka.
Poor monsoon to continue over next 2-3 weeks
"India's monsoon will continue (to be) unusually weak during the next 2-3 weeks, resulting in below-average rainfall over a large part of the nation," World Weather Inc has said in a report.
India's weather office had pegged the deficiency in rainfall at 18 per cent on July 29, compared with 27 per cent on July 15.
Poor rainfall has cast a gloom on farm output. The report says that "production potentials are at a risk and late August to early September rainfall will be the most crucial of all for the northern and central part of the nation."
"Many of the rice areas will see timely rainfall in September but the amount will be below average. The bottom line still represents a production cut," it adds.
New El Niño threatens world
A digital thermal image of El Niño that could lead to more drought in Australia
A new El Niño has begun. The sporadic Pacific Ocean warming, which can disrupt weather patterns across the world, is intensifying, say meteorologists.
So, over the next few months, there may be increased drought in Africa, India and Australia, heavier rainfall in South America and increased extremes in Britain, of warm and cold. It may make 2010 one of the hottest years on record.
The cyclical phenomenon, which happens every two to seven years, is a major determinant of global weather systems. The 1997-98 El Niño combined with global warming to push 1998 into being the world's hottest year, and caused major droughts and catastrophic forest fires in South-east Asia which sent a pall of smoke right across the region.
At present, forecasters do not expect this El Niño to equal that of 1998, but it may be the second-strongest, and concerned groups, from international insurance companies to commodity traders, to aid agencies such as Oxfam, have begun to follow its progress anxiously. Its potential for economic and social impact is considerable.
Professor Chris Folland, of the Met Office Hadley Centre for Climate Prediction and Research, said: "We are likely to see more global warming than we have seen in the past few years, which have been rather cool. In fact, we are already seeing it."
El Niño is a periodic warming of the normally cold waters of the eastern tropical Pacific, the ocean region westwards out from South America along the line of the equator. Since the Pacific is a heat reservoir which drives wind patterns around the world, the change in its temperature alters global weather. An El Niño is defined by ocean surface temperatures rising by more than 0.5C above the average.
This El Niño is well beyond that, says the Climate Prediction Center of the US National Weather Service. "Sea surface temperatures remain +0.5 to +1.5 above average across much of the equatorial Pacific Ocean," the centre reported last week. "Observations and dynamical model forecasts indicate El Niño conditions will continue to intensify and are expected to last through the northern hemisphere winter of 2009-10."
The last El Niño was in 2006-07 and, at its peak, sea surface temperatures averaged about 0.9 degrees above normal. But this is a stage which has already been reached by this one.
The last El Niño, comparatively weak though it was, is thought to have been partly responsible for the extraordinarily warm weather in Britain between the summer of 2006 and the spring of 2007: July 2006 was Britain's hottest month, autumn 2006 (September, October and November) was the warmest autumn, winter 2006-07 (December, January and February) was the second warmest in Britain, and April 2007 was our warmest April.
People have forgotten this because there then began our recent cooler and wetter period, with Britain's two "washout summers" of 2007 and 2008, and they may, in turn, have been associated with the counter-phenomenon of La Niña, a cooling of the eastern tropical Pacific waters, which followed. The start of the present El Niño was one reason the Met Office predicted a "barbecue summer" for 2009.
Weather tale of 2 cities
In Chennai, Tamil Nadu, India the average temperature is 28.63C (83.525F). 20.00C (68.00F) is the lowest monthly average low temperature (occurring in January) while 38.00C (100.40F) is the highest monthly average high temperature which occurs in May. The average temperature range is therefore 8.50C (47.30F). Wet weather in Chennai, Tamil Nadu accumulates so that there is a total average rainfall of 1217.00mm (47.91in) per annum. Divided over the year this gives an average monthly rainfall of 101.42mm (3.99in). November is the month with most precipitation when 309mm (12.17in) of rain falls over a period of 11 days while in February only 7mm (0.28in) of rain falls over 1 days. Chennai, Tamil Nadu’s weather is effected by 91 days per year with greater than 0.1mm (0.004in) of rainfall. Relative humidity at Chennai, Tamil Nadu averages 71.08333333% over the year. 59% is the lowest average monthly relative humidity which occurs in June and 80% is the highest average monthly relative humidity which occurs in November. Chennai, Tamil Nadu’s weather is effected by 2716 hours of sunshine per year which is an average of 7.44 hours per day. The range of sunlight hours is from an average of 4.8 per day in July to 9.8 per day in March. You can get more info about the Chennai weather at the world climate and temperature website. Free Chennai, Tamil Nadu climate graphs are available for you to add to your webpages.
New Delhi, India
In New Delhi, India the average temperature is 25.25C (77.45F). 7.00C (44.60F) is the lowest monthly average low temperature (occurring in January) while 41.00C (105.80F) is the highest monthly average high temperature which occurs in May. The average temperature range is therefore 20.50C (68.90F). Wet weather in New Delhi accumulates so that there is a total average rainfall of 715.00mm (28.15in) per annum. Divided over the year this gives an average monthly rainfall of 59.58mm (2.35in). July is the month with most precipitation when 211mm (8.31in) of rain falls over a period of 14 days while in November only 1mm (0.04in) of rain falls over 1 days. New Delhi’s weather is effected by 57 days per year with greater than 0.1mm (0.004in) of rainfall. Relative humidity at New Delhi averages 49.16666667% over the year. 25% is the lowest average monthly relative humidity which occurs in April, May and 73% is the highest average monthly relative humidity which occurs in August. New Delhi’s weather is effected by 2856 hours of sunshine per year which is an average of 7.82 hours per day. The range of sunlight hours is from an average of 5.6 per day in July to 9.5 per day in November. Uncover more exact details and insight on the temperature in New Delhi on the excellent linked to website. Details of the average high and low temperature for each month are available there.