Tuesday, April 13, 2010
Blast from west behind heat
Hope of cooler weather lies in Mediterranean storm
Weather records over the past decades suggest that summers in India have become hotter, but scientists today linked the extreme heat in eastern India to the flow of hot and dry winds from India’s northwest.
In Calcutta today, the maximum temperature climbed down to normal at 35.9 degrees Celsius, though the higher humidity range and power cuts denied people comfort. The high humidity has triggered hopes of a Nor’wester in the next three-four days. (See Metro)
Meteorologists said respite from the heat may be expected if a type of extra-tropical storm they called a “western disturbance” originating over the Mediterranean region moved eastward over India and then southeast along the Gangetic plains.
“A western disturbance has a cooling effect, but we haven’t felt the effects of a western disturbance in northern India for a few weeks now — hot, dry air from the northwest is moving towards the east,” said B. Bandopadhyay, a scientist at the India Meteorological Department (IMD), New Delhi.
Gaya was among the hottest places in eastern India today with a temperature of 44.8 degrees Celsius — about 6 degrees Celsius above normal.
A western disturbance currently observed over Jammu and Kashmir is moving eastward over the mountains but is unlikely to cool the plains, scientists said.
The IMD said today heat wave conditions were likely to continue over the plains of northwest India over the next 24 hours, but another western disturbance was likely to move into western Himalayas around April 15. “But the effects of this one also appear set to bypass the plains,” an IMD official said.
Across wide swathes of northern and eastern India, weather instruments recorded temperatures several degrees above the long-term normal readings. Delhi’s Palam weather office recorded a maximum temperature of 42.7 degrees Celsius, about 7 degrees Celsius higher than normal, while Lucknow and Patna both recorded maximum temperatures about 4 degrees Celsius above normal.
The heat wave, meteorologists said, appears in line with research that suggests average temperatures over India have increased over the past several decades. A study by scientists at the Indian Institute of Tropical Meteorology (IITM), Pune, has indicated that the maximum as well as minimum temperatures have increased significantly, by 0.2 degree Celsius per decade, over the past three decades.
“When the mean (average temperature) shifts to a higher level, the chances of heat waves occurring also rise,” said K. Krishna Kumar, a senior scientist at the IITM. “The number of hot days also appears to be increasing,” Kumar told The Telegraph.
A recent analysis of India’s temperature trends during the pre-monsoon months of March, April and May from 1970 to 2005 shows that the frequency of hot days and nights has increased for India as a whole — although there are regional variations.
The new IITM study, published in the Journal of Earth Sciences, shows that frequency of hot days has significantly increased over the southern parts of India, but there has been no significant change over the northern parts of India.
The Centre for Science and Environment, New Delhi, today cited a three-year-old research paper by the Indian Institute of Technology, Delhi, showing regional variations in trends in maximum and minimum temperatures.
The study by S.K. Dash, an atmospheric scientist at the IIT, analysing temperatures between 1901 and 2003 suggests that in the eastern coastal region, the maximum temperature has gone up by 0.6 degree Celsius and the minimum by 0.2 degree Celsius. In northwest India, according to the study, while the maximum temperature has increased by 0.6 degree Celsius, the minimum temperature has dropped by 0.2 degree Celsius. The IMD has said March 2010 was the second warmest March since 1901.
Rainfall on 12-Apr, Karnataka, S-W Andhra, N-E states, Himachal and Kashmir.. http://yfrog.com/6tg4xg
crippling heat wave has held centre-stage over large parts of east and northwest India during the 24 hours ... http://bit.ly/bh30Tv
After afternoon thunder showers over south-Interior Karnataka, the high dead clouds still linger over the zone.. http://yfrog.com/1rxqkj
Thunderstorms erupt in N-E as heat builds to west
Thunderstorms have erupted once again over the North-East bringing rain to many places over Arunachal Pradesh, Assam and Meghalaya during the past 24 hours ending Monday morning.
These seasonal showers triggered by north-westerly winds (Nor'westers) have steadfastly refused to venture out further to the southeast, especially over West Bengal.
RAISED CHANCES
This has led mercury to gallop to the highest in at least last 10 years' recorded history. Coverage of clouds as revealed by satellite pictures on Monday does not indicate anything to the contrary either.
According to the US National Centres for Environmental Prediction, the convective available potential energy (CAPE) values are high for areas in and around the Sunderbans and Metro Kolkata.
High CAPE values signal the probability for thundershowers, which have largely evaded this region so far. Towards the south, these values continue to be high for Kerala and adjoining south-interior and coastal Tamil Nadu.
In fact, Kerala is among the few meteorological subdivisions that have recorded normal rain during the period from March 1 to April 7, an update from India Meteorological Department (IMD) said on Monday. The others are Konkan, Goa, Assam and Meghalaya (excess); and Marathwada, Vidarbha, Arunachal Pradesh and Nagaland-Manipur-Mizoram-Tripura (normal).
HEAT WAVE
A crippling heat wave has held centre-stage over large parts of east and northwest India during the 24 hours ending Monday morning.
Parts of east-central India – Jharkhand, interior Orissa, Vidarbha and Telangana – managed to escape the blast of oppressive heat generated by the trans-Pacific ridge (high-pressure region that prevents cloud-building from taking place). This was due to proximity of these regions to a trough from Bihar running down south-southwest to north coastal Karnataka.
Meanwhile, Sambalpur in Orissa recorded the highest maximum temperature of 45.6 deg Celsius overnight on Monday. Widespread heat wave to severe heat wave conditions prevailed over many parts of Punjab, Haryana, Delhi, north Rajasthan and parts of Himachal Pradesh. Heat wave conditions also prevailed over many parts of Uttar Pradesh, Jharkhand, interior Orissa and parts of Chhattisgarh, north Madhya Pradesh, Bihar and Vidarbha.
WESTERN DISTURBANCE
The IMD traced a western disturbance lying over north Pakistan and adjoining Jammu and Kashmir. It is forecast to affect the western Himalayan region during the next 24 hours.
The system that features a core of winds cooler than the prevailing air in the northwest but packing moisture content is expected to trigger widespread rain or thundershowers over Jammu and Kashmir during the next 24 hours.
The IMD expects the thunderstorms to roll down the hills of the northwest onto the plains as well, with scattered rain or thundershowers being forecast for Himachal Pradesh, Uttarkhand, Punjab and Haryana during the same period. Satellite cloud imagery showed the presence of low to medium clouds (partly clouded conditions) over Jammu and Kashmir, parts of Himachal Pradesh, Uttarkhand and Punjab.
The cloud formation is expected to help bring down the maximum day temperatures briefly over these regions.
Westerlies from an earlier western disturbance passing into the east are already causing thundershowers over the northeast. This activity would get another fillip as the incoming system too moves, as it will, to the east and northeast.
Scattered to fairly widespread rain or thundershowers have been forecast to occur over Arunachal Pradesh, Assam, Meghalaya and isolated over Nagaland, Manipur, Mizoram and Tripura until Thursday.
Isolated rain or thundershowers would also occur over Karnataka, Kerala and Lakshadweep during this period, the IMD said.
These seasonal showers triggered by north-westerly winds (Nor'westers) have steadfastly refused to venture out further to the southeast, especially over West Bengal.
RAISED CHANCES
This has led mercury to gallop to the highest in at least last 10 years' recorded history. Coverage of clouds as revealed by satellite pictures on Monday does not indicate anything to the contrary either.
According to the US National Centres for Environmental Prediction, the convective available potential energy (CAPE) values are high for areas in and around the Sunderbans and Metro Kolkata.
High CAPE values signal the probability for thundershowers, which have largely evaded this region so far. Towards the south, these values continue to be high for Kerala and adjoining south-interior and coastal Tamil Nadu.
In fact, Kerala is among the few meteorological subdivisions that have recorded normal rain during the period from March 1 to April 7, an update from India Meteorological Department (IMD) said on Monday. The others are Konkan, Goa, Assam and Meghalaya (excess); and Marathwada, Vidarbha, Arunachal Pradesh and Nagaland-Manipur-Mizoram-Tripura (normal).
HEAT WAVE
A crippling heat wave has held centre-stage over large parts of east and northwest India during the 24 hours ending Monday morning.
Parts of east-central India – Jharkhand, interior Orissa, Vidarbha and Telangana – managed to escape the blast of oppressive heat generated by the trans-Pacific ridge (high-pressure region that prevents cloud-building from taking place). This was due to proximity of these regions to a trough from Bihar running down south-southwest to north coastal Karnataka.
Meanwhile, Sambalpur in Orissa recorded the highest maximum temperature of 45.6 deg Celsius overnight on Monday. Widespread heat wave to severe heat wave conditions prevailed over many parts of Punjab, Haryana, Delhi, north Rajasthan and parts of Himachal Pradesh. Heat wave conditions also prevailed over many parts of Uttar Pradesh, Jharkhand, interior Orissa and parts of Chhattisgarh, north Madhya Pradesh, Bihar and Vidarbha.
WESTERN DISTURBANCE
The IMD traced a western disturbance lying over north Pakistan and adjoining Jammu and Kashmir. It is forecast to affect the western Himalayan region during the next 24 hours.
The system that features a core of winds cooler than the prevailing air in the northwest but packing moisture content is expected to trigger widespread rain or thundershowers over Jammu and Kashmir during the next 24 hours.
The IMD expects the thunderstorms to roll down the hills of the northwest onto the plains as well, with scattered rain or thundershowers being forecast for Himachal Pradesh, Uttarkhand, Punjab and Haryana during the same period. Satellite cloud imagery showed the presence of low to medium clouds (partly clouded conditions) over Jammu and Kashmir, parts of Himachal Pradesh, Uttarkhand and Punjab.
The cloud formation is expected to help bring down the maximum day temperatures briefly over these regions.
Westerlies from an earlier western disturbance passing into the east are already causing thundershowers over the northeast. This activity would get another fillip as the incoming system too moves, as it will, to the east and northeast.
Scattered to fairly widespread rain or thundershowers have been forecast to occur over Arunachal Pradesh, Assam, Meghalaya and isolated over Nagaland, Manipur, Mizoram and Tripura until Thursday.
Isolated rain or thundershowers would also occur over Karnataka, Kerala and Lakshadweep during this period, the IMD said.
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