Dry air aborts squalls

Evening squalls characteristic of the season are absent from the region because of lack of moisture in the air, say weather experts.

“Rains accompanied by lightning are common in the evenings during this time of the year and they usually start by March and extend to April. The thunderstorms occur over vast swathes of the region generally, but they are limited to a few areas in the Jalpaiguri district and the neighbouring Sikkim this time,” said an official of the regional meteorological office in Jalpaiguri.

Tea planters are worried that the first flush production will be hit by the dry spell.

“There has not been enough rainfall since October last year. For the first flush, 2-4 inches of rain are required in December and January. But this year has been unusually dry and humidity, too, is relatively low,” said R. Saha, the project director of the Darjeeling Tea Research and Development Centre in Kurseong.

“We received nearly one inch of rain in mid-February but that’s not enough. If the condition prevails for the next 10 days, then the first flush tea will be severely affected. Some gardens may be irrigated, but most estates are likely to be affected by the dry spell,” added Saha.

The reason cited by weathermen is the absence of moisture-laden winds blowing from the south.

“These thundershowers are caused by the formation of cumulous and cumulo-nimbus clouds. However, moisture-laden winds from the south, which aid cloud formation, have not yet come. There are other conditions like trough formation and cyclonic circulation necessary to induce squalls. While there is a trough formation (low pressure zone) in the region, the absence of moisture has kept away the squalls,” said the weather official.

“The north-westerly winds that are currently blowing from north and central India contain no moisture and they have made the air dry,” he added.

According to the official, the intensity of rainfall during these thunderstorms usually depends on the vertical development (thickness) of the cloud. However, not less than 10mm of rainfall is usually expected.

Source: The Telegraph