Perth was struck by severe thunderstorms overnight, which flooded the city with as much as 37mm in just 30 minutes. The heavy downpours caused flash flooding around Perth and it's surrounds as severe storms spun over southwest WA overnight. The heaviest storms occurred over the Lower West and Great Southern districts, where widespread 40-80mm of rain fell in just a few hours time for most. Perth gained as much as 37mm of rain in just 30 minutes and a total of 44mm during the past 24 hours. This is the heaviest daily total for December since 1951, when 47mm fell over a 24-hour period. This brings the monthly total to 76mm, already making this the wettest December in 50 years when 81mm fell. Mandurah was drenched by its heaviest December rainfall total in more than a decade, gaining 69mm during the past 24 hours. Over the Great Southern, Wandering received 83mm in around 12 hours, which was its largest daily total for any month in at least 13 years. This record breaking December rain was the result of tropical moisture being fed into a broad trough over the state. This trough is edging east, with the heaviest rainfall expected to impact the Goldfields today.