Sydneysiders enjoying the mostly sunny morning may need a brolly for the afternoon. A low pressure trough is currently moving north, bringing a showery southerly change with it. Around mid-morning officeworkers with a view to Sydney's southeast could spot a couple of showers and thunderstorms just off the coast. One of these cells may brush the coast around lunch-time, but there is more to come. Further south, a wide thunderstorm cell is spreading along the trough and slowly moving north. It has already brought heavy falls to the Illawarra coast, with 107mm at Point Perpendicular (Jervis Bay) between 8am and midday. It will start to impact Sydney this afternoon. Western Sydney should remain pretty dry from this trough, with just the chance of a couple of showers making it inland. Showers and storms will clear during the evening with a return to mostly sunny weather tomorrow. As Sydneysiders head out and about on the weekend there is no need to worry about the brolly.