Cloud over pre-monsoon showers

As 30 out of 36 meteorological subdivisions received either zero or very little rainfall in the last one week, weather scientists have now kept their fingers crossed on having pre-monsoon showers.

“It is unusual. In April we should have thunderstorms and pre-monsoon showers in the South and North East. But there is none this time. The air is devoid of moisture,” M Rajeevan, secretary in the Ministry of Earth Sciences told DH.

As many as 12 meteorological subdivisions in central, southern and western India as well as the Andaman and Lakshadweep islands received no rain in the last one week.

The rainfall received in most other subdivisions fall in the scanty category (-60 to -99%), whereas in coastal Karnataka, showers are in the deficient (-59%) category. The only sub-division that received excess precipitation is Assam and Meghalaya. Five other sub-divisions in the East and North East besides Jammu and Kashmir and Himachal Pradesh received normal rainfall.

A comparison with last year's data showed 23 out of 36 sub-divisions had either normal or excess rainfall this time of the year. Three sub-divisions experienced zero rainfall.

“This anomaly could be due to the El Nino effect, but we need better analysis. Pre-monsoon showers take place because of a combination of atmospheric circulation and the presence of moisture in the air. The second factor is missing,” said Rajeevan.

With skies drying up, the water tables have gone down sharply. The water storage available in 91 major reservoirs is just about 22% of their capacity. The southern region is the worst affected where the water level in 31 reservoirs is just 14% of the live storage capacity.

The weather office, on Friday, issued heat wave warning for Telangana, Rayalaseema, Jharkhand and Odisha whereas people in other parts of central and western India have been advised to be on alert for heat wave-like conditions.

The heat waves over India are projected to be more intense and occur more frequently in future. Climatologically heatwaves occur during March to June, with high frequency over north, north-west, central and the eastern coastal regions of India. But the dynamics are different.

“Based on the observed patterns and statistical analyses of the maximum temperature variability, we identified two types of heatwaves. The first-type of heatwave over the north-central India associated with a weather phenomenon in North Atlantic. The second type of heatwave over the coastal eastern India is due to the anomalous cooling in the Pacific,” said Rajeevan, who analysed the head wave pattern with colleagues from India and Japan.

Last year, about 2,200 Indians died from heat wave. The toll was higher in 2003 when more than 3,000 people perished in different parts of India.