Chennai, Oct 14 (Reporter) The conditions are increasingly becoming favourable for the onset of Northeast Monsoon over Tamil Nadu and the southern peninsular India as the Low Pressure Area over southeast Bay of Bengal is set to intensify, promising heavy to very heavy rains in the State for the next three days. The Met office has already issued an Orange alert for Chennai and its neighbouring districts for tomorrow and a Red Alert, rains in excess of 20 cm, for Wednesday. A bulletin issued by the IMD on Monday said the Low Pressure area over the Bay is likely to move west-northwestwards and become well marked low pressure area over central parts of south Bay of Bengal by tomorrow. Thereafter, it is likely to continue to move westnorthwestwards towards north Tamil Nadu, Puducherry and adjoining south Andhra Pradesh coasts during subsequent 2 days. Under its influence, light to moderate rainfall over most places with heavy to very heavy rainfall at isolated places is very likely for two days and heavy to very heavy rainfall at a few places over Tamil Nadu and Puducherry with extremely heavy rainfall at isolated places over north Tamil Nadu on October 16 (Wednesday). Light to moderate rainfall over most places with heavy to very heavy rainfall at isolated places is very likely over interior Tamil Nadu on October 17. Squally weather with wind speed reaching 35-45 kmph and gusting to 55 kmph is likely to prevail over southeast and adjoining southwest and central Bay of Bengal till the evening of October 15. Thereafter, it is likely to increase becoming squally wind speed reaching 40-50 kmph and gusting to 60 kmph over southwest and adjoining westcentral Bay of Bengal and along and off Tamil Nadu, Puducherry and south Andhra Pradesh coasts till morning of October 17 and decrease gradually thereafter. Moderate to Rough Sea condition is likely to prevail over southeast and adjoining southwest and central Bay of Bengal till tomorrow evening. It is likely to become Rough Sea condition thereafter over southwest and adjoining westcentral Bay of Bengal and along and off Tamil Nadu, Puducherry and south Andhra Pradesh coasts till October 17 and improve gradually thereafter. Fishermen are advised not to venture into the sea for the next four days and the Met office has asked those who had already went to the sea for fishing to return to the shores by today. The Met office said the heavy rains could cause localized flooding of roads, water logging in low lying areas and advised closure of underpasses mainly in urban areas of the above region. There will be occasional reduction in visibility due to heavy rainfall. Disruption of traffic in major cities and roadways due to water logging in roads and poor visibility due to heavy rain leading to increased travel time and incidents, likely disruption of marine and inland water transportation like small boats and trawlers, minor damage to kutcha roads, possibilities of damage to vulnerable structure, localized Landslides/Mudslides/landslips/mud slips/land sinks/mud sinks, damage to horticulture and standing crops in some areas due to inundation and wind. It may lead to riverine flooding in some river catchments, the met office said...////...