 According to the Bureau of Meteorology, the storm formed at around midnight on the night of 2 December over Craigieburn, then grew in size as it moved in a south-easterly direction (the Bureau issued a severe thunderstorm warning based on their observations at 11.38 pm).The two hours from midnight to 2 am saw extremely heavy rainfall, with some areas recording more than 100 mm of rain in that time.The rapid rainfall caused flash flooding, which resulted in extensive damage to property.