SA - SEVERE WEATHER RISKS WEDNESDAY.

Significant storm activity has been ongoing overnight for far northern areas of the state with flash flooding occurring in outback regions, the eastern APY Lands and through to the Northeast Pastoral District.


An upper low over in WA is moving towards the east and will help to spin up a deepening surface low later today. The wind fields and deeper moisture associated with this feature moving in from the northwest will help support more thunderstorm activity developing, with flash flooding and damaging winds redeveloping.


Note the low pressure system sitting offshore VIC and that will move east but has interrupted the flow pattern for southern Ag areas meaning we sit in divergent air with not much rainfall and cooler weather. The humid and more unstable air is running north of this region and approaching from the west with the upper low and trough. Bands of strong to severe storms passing through from WA into western SA will continue today and will increase over the northern districts with all modes of severe weather once again possible this afternoon and overnight into Thursday.

Thunderstorm Analysis Wednesday

Thunderstorms are continuing to march east but as they hit the more stable air over the Ag areas, these storms are anticipated to break down into batches of light to moderate rainfall. Further severe thunderstorms are expected to fire up over the northwest and west this afternoon and march towards the southeast and east with all modes of severe weather possible this afternoon.

State of Play Wednesday

There are clusters of thunderstorms over the west coast and as mentioned in the graphic below they are currently severe on satellite imagery and presentation. There is a high chance of severe thunderstorms developing over northwest and western areas this afternoon with the approach of an upper low and developing deepening surface low. This will add the dynamic support to promote severe thunderstorms. There is the risk that updrafts may be spun into motion given the wind fields so there may be large hail and isolated tornado activity through this region coupled with the dangerous flash flood risk.

Thunderstorm Forecast Wednesday

Storms are currently active over western and northwest SA. The thunderstorms coverage will increase further again during Wednesday with severe storms likely over the northern and western areas ahead and with a low pressure system. Once the low moves east of your region, the weather turns sharply stable. There is the risk of dangerous flash flooding in the northwest and north.

Flash Flood Risk Wednesday

Heavy rainfall leading to flash flooding during Wednesday with thunderstorms, but also expected with the passage of a low pressure system over the West Coast and Eyre Peninsula later tonight and extending east through the Mid North and Flinders during Thursday. Some areas could record over 70mm of rainfall. How far south the risk does come is determined by the upper level winds and this won't be known until it is underway.

Damaging Winds Risk Wednesday

Damaging winds are likely to develop with a deep low emerging from WA but also with thunderstorms over the west and northern areas of the state, this may extend towards the EP during the late afternoon or evening.

Riverine Flood Risk This Week.

The riverine flood risk up north is high through this period with the water expected to hit the salt pans and outback lakes later this week into later this month, starting the process of flooding through the warm season. This is not a surprise given the guidance in previous months.

Stay weather aware throughout today!

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