Almost the entire south east corner of Australia under severe weather warnings

AS winds and rain again intensify in South Australia, the coastal city of Port Pirie has been warned of flooding while the town of Sevenhill is under threat from a weakened dam.

The Bureau of Meteorology has issued severe weather warnings in South Australia, Victoria, New South Wales, the ACT and Tasmania as one of the biggest storms in 50 years continues.

An intense lower pressure system continues to move across SA after super cell thunderstorms brought down the entire power network on Wednesday.

The winds ripped at least 22 transmission towers from the ground across the mid-north with about 80,000 lightning strikes hitting the state, some damaging generation facilities.

Here’s what you need to know.

SOUTH AUSTRALIA

After temporarily slowing, the foul weather has returned to South Australia with renewed ferocity.

The winegrowing Clare Valley town of Sevenhill has been issued an emergency flood warning message, with the State Emergency Service warning a dam east of the town is in danger of collapse. Residents have been advised to be on high alert and to avoid running water.

Meanwhile, the low-lying city of Port Pirie on Spencer Gulf has been warned that heavy rains combined with a tidal surge threaten to flood parts of the city. The city has only this afternoon had power restored after an almost 24 hour outage.

State Emergency Services chief officer Chris Beattie told reporters that, if the forecast conditions arrive, the storm will bring the strongest winds Adelaide has ever experienced.

Wind gusts of up to 140km/h are possible, especially along the west coast of Eyre Peninsula and up to 100mm of rain could fall across the Adelaide Hills.

The intense low-pressure system, now packing winds of 140km/h, has lashed Adelaide and parts of South Australia, causing widespread damage, coastal inundation and flooding.

The new phase of the destructive storm came 24 hours after supercell thunderstorms knocked out the state’s entire power network, ripping up transmission towers. 30,000 properties remained without power on Thursday night, some from the blackout and some because of new storm damage.

The Bureau of Meteorology says the storms will continue through Thursday night, bringing more rain and destructive winds in some areas.

The conditions will cause sea levels to be significantly higher than indicated on tide tables today. Sea levels along parts of Spencer Gulf and Gulf St Vincent coastlines are likely to be about one metre higher than the highest tide of the year, particularly in the Spencer Gulf.

At the Outer Harbor tide gauge, the sea level is forecast to reach about 3.4 to 3.8 metres. This may cause sea water flooding of low lying areas.

The high sea level and windy conditions will combine to generate heavy surf along exposed gulf coastlines, which may lead to coastal erosion and damage.

BOM has warned that there is reduced visibility due to heavy showers with strong to gale force and very gusty winds making driving conditions dangerous during on Thursday evening and Friday morning in the Adelaide Area.

BOM has also issued a warning to sheep graziers for the Mount Lofty Ranges, West Coast, Lower Eyre Peninsula, Eastern Eyre Peninsula, Yorke Peninsula, Kangaroo Island, Flinders, Mid North, Riverland, Murraylands, Upper South East, Lower South East, North West Pastoral and North East Pastoral forecast districts.

Sheep graziers are warned that cold temperatures, heavy rain, showers and strong to gale force west to southwesterly winds are expected during Thursday and early on Friday. There is a risk of losses of lambs and sheep exposed to these conditions.

There are wind warnings for the following areas: Central Coast, South Central Coast, Spencer Gulf and Investigator Strait. There are gale warnings for the Adelaide Metropolitan Waters, Upper West Coast, Lower West Coast, Gulf St Vincent and Upper South East Coast. Strong wind warnings have been issues for the Far West Coast.

VICTORIA

Winds in excess of 100km/h lashed Victoria as the front moved across the border late on Wednesday night, bringing rain and powerful winds.

There are wind warnings for Central Gippsland Coast and East Gippsland Coast, strong wind warnings for Port Phillip and Central Coast and a cancellation warning for the West Coast.

Bureau of Meteorology forecaster Dean Stewart said as the front moved across the state it would bring winds up to 100km/h and heavy rain in parts.

“We’ll have some totals of probably 20-40mm, probably even some isolated totals getting up to 50mm in those north east ranges,” he told AAP.

Heavy rain has caused minor flooding in the Glenelg River.

NEW SOUTH WALES AND THE ACT

Windy conditions are continuing for the far west and ranges of NSW.

Damaging winds averaging 50 to 70 km/h with peak gusts in excess of 90 km/h are forecast in the far west of New South Wales this afternoon and evening, as well as over the central and northern ranges and through the Hunter. Districts affected include the Upper and Lower Western, and parts of the Riverina, Central Tablelands, Hunter, Mid North Coast and Northern Tablelands.

Winds in the far west will ease overnight as the low moves east, while damaging winds are likely to persist for the central and northern ranges and Hunter through to Friday.

A Flood Watch and several Flood Warnings are current for riverine flooding in NSW.

There is a strong wind warning for Byron Coast, Coffs Coast, Macquarie Coast, Hunter Coast, Sydney Coast, Illawarra Coast and Eden Coast.

Sheep graziers have also been warned that cold temperatures, showers and strong west to northwesterly winds are expected for Thursday and Friday. Areas likely to be affected include the Central Tablelands, Southern Tablelands, South West Slopes, Riverina, Lower Western, Snowy Mountains and Australian Capital Territory forecast districts and parts of the Hunter, Northern Tablelands, Illawarra, South Coast, North West Slopes & Plains, Central West Slopes & Plains and Upper Western forecast districts. There is a risk of losses of lambs and sheep exposed to these conditions.

TASMANIA

A severe weather warning for damaging winds and heavy rains has ben issued for much of the east of Tasmania as a small but deep low-pressure system moves slowly south along the coast.

Damaging northeasterly winds averaging between 60 and 70km/h, with gusts of up to 100km/h, are expected along with heavy rains.

A flash flood warning is in place in the east, and there are warnings rivulets around Hobart and elsewhere in the southeast could rise rapidly.

QUEENSLAND

There is a strong wind warning for the following areas; Fraser Island Coast, Sunshine Coast Waters and Gold Coast Waters. The strong winds will continue on Friday with warnings for the Capricornia Coast, Fraser Island Coast, Sunshine Coast Waters and Gold Coast Waters.