Weather over north-west India, strategically crucial from the viewpoint of the health of the standing rabi crop and its prospects, is undergoing a critical transition from winter (spring) to summer.
BEST WINTER
This is the one of the most testing times to read weather and the need for accurate forecasts, especially with regard to fluctuations in temperature, cannot be gainsaid, says Dr Akhilesh Gupta, leading operational forecaster and Adviser to the Department of Science and Technology.
The 2009-10 winter has been one of the best with adequate rainfall and low temperatures which have stood the rabi wheat crop in great stead, Dr Gupta told Business Line.
Given this context, it is not outlandish to expect a bumper crop this year, but with a caveat. And this has reference to only the uptrend in temperature during the most vulnerable period, as emerges now, when the crop is reaching maturity.
The situation is made trickier by the fact that the harvest festival of ‘Holi' falls on March 1 this year, much earlier than usual. Normally, ‘Holi' falls in late March to coincide with the time around which harvesting operations begin.
But this time round, farmers would need to wait almost a month post-Holi for harvesting to begin. By then, the temperature regime would have made a decisive turn to inch up marking the turn from spring to summer, Dr Gupta said.
The maximum temperature is expected to start looking up as early as from this Friday February 26. A rise in maximum temperature is often mistaken to mean the advent of summer.
MINIMUM TEMPERATURE
The transition to summer is complete only when the minimum temperatures too starts rising, which would be around March 1 this season, the day of Holi, Dr Gupta said. This would leave the crop to the mercy of the elements for at least a month.
The maximum temperature level over the plains of northwest India is currently in the range of 27-28 deg Celsius. The upper threshold limit is 30-35 deg Celsius beyond which the mercury would have a debilitating impact on the crop.
Only western disturbances, one of which is currently holding sway, can help moderate the climes in the north and northwest. But forecasts indicate no big system arriving into the northwest until March 1 to bring along cloudiness and rains. Some weak systems are expected to check in during this phase but their influence would be limited to within the hilly regions of the northwest – that is western Himalayas.
WESTERLY SYSTEMS
While a western disturbance is currently in the final stages of its activity over the western Himalayas, a fresh one is approaching and will start impacting the region from Wednesday, India Meteorological Department (IMD) said.
(vinson@thehindu.co.in)
Minimum temperatures are above normal by 2-5 deg Celsius over parts of Madhya Pradesh, Rajasthan, Gujarat, Haryana, Punjab, north Karnataka and Andhra Pradesh.
Maximum temperatures too are above normal over south Maharashtra, Andhra Pradesh, Orissa, Madhya Pradesh, Chhattisgarh, Gujarat, Rajasthan, Haryana, Himachal Pradesh, Jammu and Kashmir and the north eastern States.
Isolated rain or snow has been forecast over Jammu and Kashmir during next two days and may increase thereafter. Isolated to scattered rain or snow is also likely over Himachal Pradesh from Thursday and over Uttarakhand from Friday.
Isolated light rain or thundershowers is likely over Haryana and west Uttar Pradesh during the next 24 hours. Isolated to scattered rain or thundershowers would occur over the north eastern States also.
Wednesday, February 24, 2010
Tuesday, February 23, 2010
Monsoon likely to be normal, says US forecaster
The International Research Institute (IRI) for Climate and Society at Columbia University is the latest forecasting agency to affirm enhanced probability for a largely ‘normal' monsoon for India this year.
But the initial phase leading up to the onset phase and advancement (April-May-June) is loaded with probability for below normal precipitation for eastern India – covering north coastal Andhra Pradesh, Vidarbha, Orissa, Chhattisgarh, Jharkhand, Bihar and Gangetic West Bengal.
BEYOND BORDER
While north-east India could likely see normal onset and advancement conditions, probability for below normal precipitation is indicated for neighbouring countries of Bangladesh, Myanmar, Thailand, Vietnam, Laos, and parts of south and west China.
Northern half of Pakistan is tipped to receive excess showers during this phase, while ‘drought masking' is applicable for the southern half, the IRI outlook suggested.
May-June-July that coincides with advancement and maturity of the monsoon is projected to return normal rainfall figures for entire India (including east India that may have gone under-fed until then) and Pakistan.
But the enhanced probability for below-normal precipitation would be still valid for Bangladesh-Myanmar, Vietnam and Thailand.
The fully mature monsoon during June-July-August is once again shown to be normal over India, Pakistan, entire South-East Asia and China.
This is the phase that scientists at the Tokyo-based Research Institute for Global Change (RIGC) have identified with the dying of the prevailing El Nino conditions over central Pacific and likely return of the reverse phenomenon of La Nina.
A La Nina has been traditionally considered to favour a concurrent Indian monsoon, though not with direct cause-effect relationship.
The RIGC has said in updated forecast that it expects to see a weak positive Indian Ocean Dipole at work during September-October-November.
PENINSULAR HEATING
Like La Nina, a positive IOD is also known to rub off positively on the Indian monsoon, though the timing would be too late for this year.
In positive IOD conditions, warm temperature anomalies shift to western Indian Ocean, helping catalyse the favourable impact on monsoon for mainland India, especially the central and western parts.
As for expected temperature regime for the country, the IRI said that the odds have stacked up to signal enhanced probability for some of the worst heating to get concentrated over peninsular India during March-April-May and April-May-June.
This region would have to wait until after the monsoon has entrenched its presence in May-June-July to get some reprieve, the IRI forecasts indicate. There is up to 70 per cent probability that this region, along with most of the west coast, would be subjected to maximum heating (to a level variously higher than even in the northwest) during the two back-to-back quarters.
Meanwhile, India Meteorological Department (IMD) has gone on record saying that the threat from El Nino, which contributed to the worst monsoon rains in India in nearly four decades last year, has subsided, raising hopes of ‘normal' monsoon rains this year.
WESTERN DISTURBANCES
On Sunday, the IMD said that it expected back-to-back western disturbances to drift into the northwest during this week from across the border signalling snow and rains for the hilly regions and adjoining respectively.
The first in the series is forecast to affect northwest India on Monday and Tuesday while the follow-up system is tipped to enter the region from Thursday even as northwesterly to westerly winds have gathered pace over the plains. Minimum temperatures are expected to look up during the arrival phase of the systems.
An IMD outlook for the next few days said that isolated rain or snow would occur over Jammu and Kashmir on Sunday while it would be and scattered on the next two days. Isolated to scattered rain and snow has been indicated for Himachal Pradesh and Uttarakhand as well on Monday and Tuesday. Isolated rain or thundershowers might occur over plains of northwest India.
But the initial phase leading up to the onset phase and advancement (April-May-June) is loaded with probability for below normal precipitation for eastern India – covering north coastal Andhra Pradesh, Vidarbha, Orissa, Chhattisgarh, Jharkhand, Bihar and Gangetic West Bengal.
BEYOND BORDER
While north-east India could likely see normal onset and advancement conditions, probability for below normal precipitation is indicated for neighbouring countries of Bangladesh, Myanmar, Thailand, Vietnam, Laos, and parts of south and west China.
Northern half of Pakistan is tipped to receive excess showers during this phase, while ‘drought masking' is applicable for the southern half, the IRI outlook suggested.
May-June-July that coincides with advancement and maturity of the monsoon is projected to return normal rainfall figures for entire India (including east India that may have gone under-fed until then) and Pakistan.
But the enhanced probability for below-normal precipitation would be still valid for Bangladesh-Myanmar, Vietnam and Thailand.
The fully mature monsoon during June-July-August is once again shown to be normal over India, Pakistan, entire South-East Asia and China.
This is the phase that scientists at the Tokyo-based Research Institute for Global Change (RIGC) have identified with the dying of the prevailing El Nino conditions over central Pacific and likely return of the reverse phenomenon of La Nina.
A La Nina has been traditionally considered to favour a concurrent Indian monsoon, though not with direct cause-effect relationship.
The RIGC has said in updated forecast that it expects to see a weak positive Indian Ocean Dipole at work during September-October-November.
PENINSULAR HEATING
Like La Nina, a positive IOD is also known to rub off positively on the Indian monsoon, though the timing would be too late for this year.
In positive IOD conditions, warm temperature anomalies shift to western Indian Ocean, helping catalyse the favourable impact on monsoon for mainland India, especially the central and western parts.
As for expected temperature regime for the country, the IRI said that the odds have stacked up to signal enhanced probability for some of the worst heating to get concentrated over peninsular India during March-April-May and April-May-June.
This region would have to wait until after the monsoon has entrenched its presence in May-June-July to get some reprieve, the IRI forecasts indicate. There is up to 70 per cent probability that this region, along with most of the west coast, would be subjected to maximum heating (to a level variously higher than even in the northwest) during the two back-to-back quarters.
Meanwhile, India Meteorological Department (IMD) has gone on record saying that the threat from El Nino, which contributed to the worst monsoon rains in India in nearly four decades last year, has subsided, raising hopes of ‘normal' monsoon rains this year.
WESTERN DISTURBANCES
On Sunday, the IMD said that it expected back-to-back western disturbances to drift into the northwest during this week from across the border signalling snow and rains for the hilly regions and adjoining respectively.
The first in the series is forecast to affect northwest India on Monday and Tuesday while the follow-up system is tipped to enter the region from Thursday even as northwesterly to westerly winds have gathered pace over the plains. Minimum temperatures are expected to look up during the arrival phase of the systems.
An IMD outlook for the next few days said that isolated rain or snow would occur over Jammu and Kashmir on Sunday while it would be and scattered on the next two days. Isolated to scattered rain and snow has been indicated for Himachal Pradesh and Uttarakhand as well on Monday and Tuesday. Isolated rain or thundershowers might occur over plains of northwest India.
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