Monsoon feel before June 7 date

According to Khole,the parameters include the pressure gradient over the Arabian Sea and Bay of Bengal,increase of cross-equatorial wind flow and the northward movement of the cloud cover from the equatorial regions to the Indian region. All this will result in high intensity of rainfall activity in the region.

With the onset also marked by parameters of high intensity rainfall for over two consecutive days in 14 stations in Kerala,Thursday saw these stations record 80 per cent rainfall. The IMD will evaluate the rainfall activity on Friday to declare the onset. “All the stations should have received a minimum 2.5 mm rainfall activity for two days for the announcement to be made,” she said.

Last year,the southwest monsoon had hit the Kerala coast on May 31,two days after the date set by the IMD. Earlier this month,the IMD had issued an onset forecast that the monsoon will touch the Kerala coast on May 26,ahead of the normal date of June 1,with a plus or minus four-day error. “The forecast has been accurate,” Khole said. The IMD has been tracking the monsoon onset from May 22.

Director of National Climate Centre Dr S Pai said the onset is declared on basis of various parameters. “We have set the criteria that 14 stations should receive 2.5 mm rainfall with 60 per cent average,while the westerlies or the winds over the Arabian sea should be at 15 m per second and the wind pressure should be at 600 hpa. We had already given the date as May 26 with a four minus or plus error,” he said.

In April,the IMD had said the average monsoon for the season was likely to be 96 per cent of the long-term average. The long period average rainfall over the country as a whole for 1941-1990 is 89 cm.