SYDNEY, Nov. 30 (Xinhua) -- Southern and eastern Australia has been warned to prepare for "unprecedented" thunderstorms which could lead to flash flooding.
The Bureau of Meteorology (BOM) issued a warning on Thursday morning that heavy rain and thunderstorms would hit the state of Victoria on Thursday night and continue for at least two days.
Parts of the state have been warned to expect more than three times its average monthly rainfall in a 48-hour period.
Scott Williams, BOM senior forecaster, said Melbourne and the state's north-east would be hardest hit on Friday night and Saturday morning, marking a wet start to summer.
"I don't think I've ever seen such a deep low form over Victoria whilst we've got this moisture around," Williams told the Australian Broadcasting Corporation (ABC) on Thursday.
"So to that extent we are a little bit in unchartered territory in terms of the weather.
"This is a very big event, a very widescale event and it's right at the top end of rainfalls that we've seen in Victoria in the last 30 years."
The north-east ranges of Victoria could experience up to 300 millimeters of rainfall over the weekend, five times more than is typical in a thunderstorm at this time of the year.
The thunderstorms come after the state has sweltered through November with Melbourne breaking the record for the number of days with a maximum temperature exceeding 30 Celsius degrees in the month.
"November traditionally is a thundery time. It's our peak season for thunderstorms and we do get heavy rain but I'm talking heavy rain as 50, 60 maybe 100 millimetres," Williams said.
"When you're talking 150, up to 300 millimeters on the ranges, that makes it unprecedented."
