Monsoon rains to reach Kerala coast on June 3

“After the actual onset of monsoon rains over Kerala,we will give advance sequence of its progress across the country,” D S Pai,head of long range monsoon forecast of IMD told FE.

According to an IMD statement,the southwest monsoon normally advances over Andaman sea around 20th May with a standard deviation of about one week.

“This year under the influence of tropical cyclone ‘Mahasen’ currently located over the central Bay of Bengal,this may lead to advance of monsoon over Andaman Sea slightly earlier than its normal date,” IMD said.

Since 2005,IMD has been been issuing operational forecasts for the date of monsoon on set over Kerala using an indigenously developed statistical model with a model error of 4 days

Last month,Science and Technology minister S Jaipal Reddy while releasing the first long-range forecast for the southwest monsoon by the IMD had stated that the monsoon this year is most likely to be ‘normal’.

According to met department,the quantitative seasonal rainfall during the southwest monsoon months (June-September) is likely to be 98% of the long-period average (LPA) or the average countrywide annual rainfall (89 cm) recorded between 1951 and 2000.

In April last year,the IMD had predicted normal rainfall of 99% of the LPA for the four monsoon months while the actual rainfall turned out to be only 92% of the LPA,leading to many parts of the country,including Maharashtra,Gujarat and Karnataka,facing drought-like conditions.

Using a combination of dynamic and statistical models,the IMD’s forecast stated that rainfall during the monsoons months would most likely be normal in the range of 96-104% of the LPA. Reddy said that probability of a normal monsoon is high with the probability of 46% while the probability of seasonal rainfall to be below normal is only 27%.

Last year,the monsoon began on a brisk note in June and then lost momentum during the latter part of the month. The rains picked up again in July. The break in rains from June-end to July adversely impacted kharif production. India’s grain output is expected to be around 250-255 million tonne (mt) in 2012-13,down from last year’s record output of 259 mt.

The IMD classifies the monsoon rainfall into categories such as deficient (less than 90% of the LPA),below normal (90-96% of the LPA),normal (96-104% of the LPA),above normal (104-110% of the LPA) and excess (above 110% of the LPA).

FE last week had reported that the South Asian Climate Outlook Forum that met rin Kathmandu in its prediction has stated the “large-scale summer monsoon rainfall will mostly likely to be within the normal range with a slight tendency towards higher side of the normal range”.