A complex low pressure system and cold front are affecting the southwestern parts of the country in coming days, leading to some welcome if gusty showers over Perth. As of 9am this morning, the city had received only about 47mm this month, just over 50% of September's long-term average rainfall. The event is expected to bring at least 10 to 20mm to Perth between now and Tuesday, with the possibility of heavier falls over parts of the metro. The system should broaden onto the coast and interior throughout Sunday and Monday, leading to widespread showers and at least some thunderstorms across the southwestern parts of the country. The west and south coasts and their immediate interiors could pick up 20 to 40mm of rainfall into Tuesday, with 10 to 20mm indicated for much of the southwestern interior. After a brief spell of drying out, another rainfall event is likely to impact the southwest on Thursday.