As temperatures zoom northwards,the wait for south-west monsoon could be a bit longer with the weatherman saying the annual rains would arrive in Kerala only next week.
“There is no further progress as yet,” India Meteorological Department’s (IMD) chief forecaster D Sivananda Pai told PTI when asked about the progress of monsoon.
Weather scientists said conditions were becoming favourable for further advance of monsoon over some parts of the Bay of Bengal during the next three days.
However,scientists do not see this as an indication towards an early onset over Kerala.
“We stick to the IMD’s forecast of monsoon onset over Kerala by June 3,” Swati Basu,director of National Centre for Medium Range Weather Forecasting told PTI.
The monsoon rains,crucial for India’s agro-based economy,brought first showers to the Andaman Sea on May 17,three days earlier than the usual date,aided by the then
raging cyclone Mahasen.
It made some headway between May 17 and May 20 but has not moved any further since.
Cyclone Mahasen,which ravaged coastal Bangladesh and parts of Myanmar,sucked up moisture in the monsoon winds,leaving them dry.
“Cyclonic activity weakens monsoon flow. It takes some time to reorganise,” Pai said when asked about the reasons for the delay in onset over Kerala.
Mercury levels have been rising across north India for the past week with temperatures crossing 45 degree Celsius in parts of Rajasthan,Haryana and Punjab yesterday.
Monsoon watchers expect a strong phase of rainfall in the first week of June after the onset over Kerala,an activity attributed to the wet phase of the Madden-Julian Oscillation (MJO) wave that passes over the Indian Ocean during the period.
The MJO is a fluctuation of atmospheric pressure over the equatorial Indian Ocean and western Pacific Ocean that comes in the form of alternating cyclonic (wet) and anticyclonic (dry) regions that enhance and suppress rainfall respectively.
Last month,the weather office had forecast normal monsoon this year with overall rainfall expected to be 98 per cent of the long period average.
Monsoon is crucial for kharif crops like rice,soyabean,cotton and maize as almost 60 per cent of the farm land in the country is rain-fed.
While IMD’s short-term weather forecasts have been by and large accurate,it is the monsoon predictions which have received flak from several quarters.
The most recent example of the shortcoming of the IMD was last year’s forecast,when it predicted 99 per cent rains of the long period average,while the actual figures stood at 92 per cent with Gujarat,Maharashtra and Karnataka facing drought conditions.
The IMD had also predicted normal monsoon season in 2009,which ended with 22 per cent deficient rains — the worst in at least four decades.
Scientists attribute this to the deficiencies in the monsoon forecast model which was unable to capture the regional variations in rainfall.
Basu said the Ministry of Earth Sciences has embarked on augmenting observation facilities and high power computing capabilities of the IMD with stress on satellite-based observations.
The IMD has a High Power Computing System (HPCS) with a capacity of around 120 teraflops located at several institutes across the country.
“We need to do better and further augment the observation systems,including the HPCS,” Basu said,adding that the Ministry would enhance its computing facilities to one petaflop level by next year.
Faster and more powerful computers would enable weather scientists to run high resolution global weather prediction models.
In addition to this,the Ministry has also launched a National Monsoon Mission to develop dynamic forecasting models for the country.
The Rs 400 crore Mission has been tasked with implementing dynamic forecasting system for making predictions across all time scales –short range to seasonal — with
The dynamic model bases its predictions on factors including sea surface temperature,formation of clouds and wind direction,rather than pure mathematics as used in the statistical models in vogue since the 1980s.
The seeds of the Mission were sown after the jolt the IMD received in 2009 when the country faced 22 per cent deficient rains as against a forecast for normal monsoon.
The need for weather forecasts was first felt after a disastrous cyclone hit Kolkata in 1864 and the subsequent failure of monsoon in 1866 and 1871.
The first monsoon forecast was issued by H F Blandford,the first Meteorological Reporter to the Government of India.
The IMD has come a long way since relying on thermometers and barometers for its forecast to the great dependence on satellite data at present.
The IMD also takes into account experimental forecasts of scientists from Space Applications Centre,Ahmedabad,Indian Institute of Science,Bangalore,Centre for Mathematical Modelling and Computer Simulation,Bangalore and Centre for Development of Advanced Computing,Pune.
Forecasts of institutes including the National Center for Environmental Prediction,US,International Research Institute for Climate and Society,US,Meteorological Office,UK,Meteo France,the European Center for Medium Range Weather Forecasts,Japan Meteorological Agency and Japan Agency for Marine are also incorporated in the IMD prediction.
A more recent development has been of regular meetings of the weather scientists from the SAARC region in April every year at which they come out with a consensus statement on the monsoon forecast for the region.