A burst of rain and thunderstorms will lash the southwest corner of Australia tomorrow at the start of a wet week in WA. Showers will develop tonight as a cold front clips the southwest corner of the state, before a low pressure system develops tomorrow and causes conditions to deteriorate further. Rainfall totals of 20-40mm are likely to the southwest of a line from about Albany to Bunbury tomorrow, with some places picking up more than 50mm. While these falls are not unusual at this time of year, it could be the heaviest rain in a few months for some locations. If Cape Leeuwin receives more than 21mm in 24 hours it will be their heaviest rain since March. At Manjimup, 20mm tomorrow would be its highest daily rainfall total since last winter. Showers are also likely to spread along other parts of the state's western and southern coasts during Tuesday. While some of these may fall in Perth, the city will miss out if the heaviest falls. Showers will continue to affect the west coast on Wednesday and begin to spread further inland as well. Looking further ahead, wet weather will continue through the second half of the week, although there is some uncertainty regarding the distribution of rainfall from Thursday onward. Most areas southwest of a line from Carnarvon to Eucla have a chance of seeing some rain by the weekend.