Heavy rain will become a regular feature across the Northern Territory Top End this week as the monsoon trough returns. A flood advice has been issued for the Arnhem and Roper-McArthur districts with showers and storms ready to increase over coming days as heavy rain develops into Monday night. Coastal parts of these districts are most at risk with localised flooding of streams a significant risk. The monsoon trough will form over the Arafura Sea over the next couple of days with the possible development of a low pressure system on Tuesday or Wednesday. The Darwin - Daly may also be included in the flood advice over coming days as heavy rain is likely to reach that region on Tuesday and Wednesday. Beyond Tuesday models begin to significantly disagree about the position of any low pressure system or the focus of heavy rain. However, there are some indications that the heavy rain will continue to gradually shift further west, particularly if a low fails to develop. The monsoon trough should head north away from the Northern Territory in about a week-and-a-half's time, taking the heaviest rainfall offshore.