Hyderabad: The state has received 24 per cent excess rainfall this monsoon season with officials from the Indian Meteorological Department (IMD) stating that this was an erratic monsoon caused by cumulonimbus clouds formation (which generally happens during the pre-monsoon period of April-May) and successive formation of low-pressure areas in Bay of Bengal.

According to IMD officials, the actual monsoon season will be for 122 days, during which time, there won’t be continuous rainfall. A trigger mechanism called synoptic situation, which are like low-pressure areas and upper air cyclonic circulations form pressure in Bay of Bengal, west central Bay of Bengal and near North Andhra Pradesh.

The officials said that normally every month during the monsoon season two to three such systems form. This results in overcast sky lasting up to five days at a stretch and is particularly visible in coastal Andhra Pradesh and neighbouring areas in Telangana.

“During the first 40 to 45 days, we didn’t see any such formations in Bay of Bengal, north Odisha coast and West Bengal. There may have been cloudy skies but there were no rains. From the last week of July, there was simultaneous formation of low-pressure areas adjacent to the west central Bay of Bengal. There was one such formation in the last week of July and four in August,” said meteorologist G N R S Srinivas Rao.

He said that the state had a 30 per cent deficit rainfall from June 1 to July-end. Now there has been an additional 24 per cent, he said.

Srinivas Rao said that they had seen another phenomenon this time around. Whenever these kinds of synoptic systems happen in the gap (dry spells), the temperatures are rising, which were not seen in the previous years.

“Normally the availability of moisture is more during dry days. Moreover, monsoon winds will prevail in the upper air during evenings. The cumulonimbus cloud development are features of the pre-monsoon season during April-May,” he said.

According to officials, as of the third week of September, the state received over 890 mm rainfall since June 1, which is more than the average rainfall of over 700 mm. The IMD predicts overcast conditions and rains and sounded a yellow alert till September 28.