The drought-prone Rayalaseema region received an average rainfall of 71 cm, 51% excess, during June 1 to Oct 15, 2017.
Incidentally, the districts in Rayalaseema and Nellore district, which are considered ‘rain shadow’ region, received exceptionally good rains during the recent south-west monsoon.
The good rain in these two regions can be attributed to the formation of two well-marked low pressure areas during August.
Rayalaseema region also received excess rainfall in September due to break monsoon conditions and ill-defined synoptic movement of the systems from east to west, activating the existing trough from Chhattisgarh to South Tamil Nadu across Rayalaseema, a retired Director of the IMD P.V. Rama Rao told The Hindu .
Mr. Rama Rao collected the data from the Meteorological Centre, Hyderabad, and analysed it based on the study of weather systems and their influence on rainfall distribution.
The south-west monsoon (June 1 to Sept 30) is the main rainy season over AP and Telangana.
While Telangana receives 75 cm, being 80% of its annual normal rainfall of 94 cm, coastal Andhra Pradesh (excluding Prakasam and Nellore) receives 70 cm, 64% of the annual normal rainfall of 108 cm, while Rayalaseema receives 40 cm, i.e., 56% of its normal annual rainfall of 71 cm.
The Prakasam district receives 38 cm, 47% of its annual normal of 71 cm and Nellore district receives 35 cm, being 32% of its annual normal rainfall of 109 cm.
“During the south-west monsoon season, the eastern parts of south peninsular India, south of 16 degrees north latitude, do not get enough rain, as they are shielded by the Western Ghats and hence they are known as ‘rain shadow areas’.
Tamil Nadu, Rayalaseema and adjoining districts of Nellore and Prakasam come under this area,” says Mr. Rama Rao.
The groundwater levels recorded a sharp rise by 8.78 m (29 feet) in Rayalaseema during the same period.
