THE much-awaited monsoon is likely to hit the Kerala coast on May 29 this year. The Indian Meteorological Department (IMD), using an indigenously developed forecast model, maintained on Wednesday that the forecast implied a model error of +/- four days from that date. The mean monsoon onset date over Kerala is June 1, two days later. The IMD said that for predicting the 2008 monsoon onset over Kerala, the IMD's model based the forecast on six predictors: Minimum temperature over northwest India, pre-monsoon rainfall peak over south peninsula, outgoing long wave radiation (OLR) over south China Sea, lower tropospheric zonal wind over southeast Indian ocean, upper tropospheric zonal wind over the east equatorial Indian Ocean and outgoing long wave (OLR) over south-west Pacific region. The Met department has been issuing operational forecasts for the monsoon onset over Kerala using statistical techniques since 2005. In 2007, the IMD predicted May 24 as the date of monsoon onset. Actual monsoon onset took place 4 days later. IMD has now prepared the forecast for the 2008 monsoon onset over Kerala based on statistical methods. Meanwhile, the southwest monsoons have advanced into southeast Bay of Bengal, Andaman and Nicobar Islands and north Andaman Sea on May 12, almost 8 days in advance. With strengthening and deepening of monsoon winds and widespread rainfall, the northern limit of the monsoons (NLM) advanced further towards the mainland sub-continent on May 13, the Met department said.