Monsoon likely to arrive on May 26 over Kerala

The IMD said monsoons were expected over the Andaman Sea in the next two or three days.

?The monsoon onset over Kerala in 2009 is likely to be on May 26, it said, adding its forecast model had an error margin of four days.

The onset of rains will help farmers plant summer crops early, but the size of the harvest would depend on the amount of rainfall and its distribution across different parts of the country.

Last year, IMD had predicted that the monsoon will arrive over Kerala on June 1, while it actually came on May 31, just a day ahead of its normal onset.

In April, the weather office said the June-September monsoon was likely to be ?near normal?.

As per the Met department?s prediction, the southwest monsoon this season would be 96% of the long period average (LPA).

The department has kept a model error of 5%.

?Quantitatively, monsoon season rainfall is likely to be 96% of the long period average with a model error of ? 5%,? the Met department said.

The LPA rainfall over the country as a whole for the period 1941-1990 is 89 cm and a 96% outcome would be the weakest since a relatively dry spell in 2004, which was followed by years in which the monsoon exceeded 98% of the average.

However, scientists at the weather office said the LPA forecast, though on the lower side, was not a cause for worry.

The southwest monsoon enters the mainland around June and starts retracing from September onwards.

The Met department?s ?near normal? prediction is based on the fact that this year the El Nino system that brings drier weather is unlikely to appear. Instead, it is the La Nina phenomenon, which could bring good rains is more prevalent.

IMD will update the above forecast in June 2009 as a part of the second stage forecasts.

The operational forecast issued by IMD for the 2008 seasonal rainfall over the country as a whole was accurate as the first and second stage forecasts were 99% and 100% of LPA, respectively, and the actual rainfall was 98% of LPA.