The Hindu Business Line : Fresh `low' promises another wet spell

THE torrential rainfall over the past few days may have reduced in intensity and the sun emerged out of the clouds in many parts of the peninsula on Friday, but a warming Bay of Bengal will not allow the reprieve to last much long.

A fresh cyclonic circulation persisting over southeast Bay of Bengal has raised prospects of concentrating into the next `low' in two days' time and move westwards to the peninsular coast.

What is required now is for the associated cloudiness to organise itself to set up the `low', said Dr L.S. Rathore of the National Centre for Medium Range Weather Forecasting (NCMRWF). The warming anomaly in the southeast Bay of Bengal will help catalyse the process. This could mean that the lull could break as early as the middle of next week with coastal Tamil Nadu and Pondicherry expected to get a fresh spell of rain.

Speaking to Business Line, Dr Rathore said an interesting feature of system formations in the Bay of Bengal in recent times is that connective heating of the land in and around northern Tamil Nadu has been guiding the dynamics. As the warmer air rises by convection, cooler air is drawn from the ocean to fill the void. The warmer air mass returns to sea at higher levels to complete a convective cell.

The greater the temperature differences between land and sea, the stronger the land and sea breezes. Regardless of temperature scale, during daytime, land temperatures might change by tens of degrees, while water temperature change by less than half a degree only.

Meanwhile, Thursday's `low' over the central parts of southeast Arabian Sea persisted on Friday. It is likely to move farther out into the sea in a west-northwest direction.

According to Dr Rathore, this has resulted in further elongation of the east-west shear zone. Given this scenario, rainfall activity over the south peninsula is likely to remain subdued during the next two-three days.

The NCMRWF maintained its outlook for an approaching western disturbance, the biggest in size of the season yet, with hilly regions of northwest India under direct line of sight. This is expected to cause precipitation over Jammu and Kashmir, Himachal Pradesh, Uttaranchal and plains of northwest India for three days from Sunday. Mercury is likely to fall appreciably over north India in its wake.

Surplus maintained: Both Andhra Pradesh and Tamil Nadu managed to retain their surplus rain record into the last week of November during the ongoing northeast monsoon season. The indifferent run observed in Kerala also persisted.

All three meteorological subdivisions in Andhra Pradesh — Coastal Andhra Pradesh (+68 per cent), Telengana (+79 per cent) and Rayalaseema (+102 per cent) — returned surplus figures. In the met subdivision of Tamil Nadu and Pondicherry, the districts of Tirunelveli and Tuticorin appreciably reduced their rainfall deficits week-on-week. The rest fell into the excess or normal categories, as has been the trend throughout the season till now.

Article E-Mail :: Comment :: Syndication :: Printer Friendly Page