Weather News

Flooding start to summer in multiple states

Ben Domensino, Thursday November 30, 2017 - 12:44 AEDT

A widespread rain and thunderstorm event will affect SA, Victoria, Tasmania, NSW and Queensland during the opening days of summer, with flash and riverine flooding likely in multiple states.

A prolonged spell of warm and humid northerly winds over Australia's southeastern states has allowed the atmosphere to become loaded with moisture. This pool of muggy air near the surface is about to interact with a pulse of colder and drier upper-level air, triggering a multi-day outbreak of rain and thunderstorms.

On Thursday, a low pressure trough moving over SA will produce a broad area of rain and storms. Shower and thunderstorm activity will also affect parts of Tasmania, Victoria, NSW and Queensland today, due to the large pool of warm and humid air ahead of the approaching trough.

The heaviest and potentially most dangerous rainfall from this event will occur between Friday and Sunday, as the trough moves further east and causes a low pressure system to develop over the nation's southeast.

Widespread rainfall totals of 50-100mm are likely for parts of Victoria and southern NSW between now and Sunday night, with similar falls also possible in parts of Tasmania.

The heaviest falls during this time are expected to occur in Victoria's mountainous northeastern districts, where event totals of 200-300mm are possible.

Some places are likely to exceed their entire monthly average rainfall totals for December during the next three days. For example, Victoria's alpine region usually receives 100-150mm during all of December and could collect more than 300mm by Sunday.

This rainfall is likely to produce both flash and riverine flooding. As of midday AEDT on Thursday, the Bureau of Meteorology had issued flood watches for minor to major flooding in parts of NSW and Victoria and minor flooding in Tasmania.

A severe weather warning was also in place for heavy rainfall that may cause flash flooding in all districts of Victoria from tonight through to the weekend.

The eastward-moving trough will also produce showers and thunderstorms across NSW and Queensland this weekend.

Most of the rain and storms in NSW will occur on and west of the ranges and in the states northeast between Friday and Sunday. Many areas along the coast will miss out on heavy falls from this system, including Sydney.

The trough will cause showers and storms to increase over western and southern Queensland on Saturday, before targeting the state's central and eastern districts from Sunday into early next week.

Severe thunderstorms are likely in both Queensland and NSW this weekend and at the early next week. These storms are likely to produce heavy rain, which could cause localised flash flooding.

The latest warnings around the country are available here:

- Weatherzone

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