imd officials say the present heat wave is not an unusual phenomenon. “The heat wave will not persist for a longer time,” says S R Kalsi, deputy director general of imd . The heat wave is “due to the lack of effective western disturbances and stagnating high pressure in the western part of the country”, notes R K Dutta, former head of the National Centre for Medium Range Weather Forecasting in New Delhi.

Western disturbances occur when troughs or lean pressure areas, either at the surface or in upper air, lie in the regimes of prevailing westerly winds, explains an imd official in New Delhi. Widespread rain in winter is generally associated with western disturbances that move across the northern parts of South Asia, where they have a marked control over the weather, notes the official.U S De, additional director general of meteorology at the Central Observatory of imd at Pune, was quoted in the media to have said: "This year the thunder-shower activity has been subdued so far, and this is making us worry. We cannot rule out the repetition of last year"s developments. Even Gangetic West Bengal has not seen rainfall activity so far."

While this can explain the weather conditions in the northern and north-western India, it still does not explain the intense spell of heat in Orissa. This year, the heat wave hit Orissa as early as the last week of February. In the first week of April, temperature was rising above 40