Severe storm targets South Australia
South Australia has been hammered this past winter and early spring by relentless storms and significant rainfall events. The reason for the higher than average rainfall is linked to some of the warmest ocean temperatures ever recorded off the Indonesian coast through autumn and winter.
When this occurs it is known in climate terms as a negative Indian Ocean Dipole (IOD) event. Without getting too scientific, this occurs when warmer than average water builds up in the Eastern Indian Ocean, along with cooler water upwelling off the African coast.
This warm water provides moisture for north-west cloud bands that drift down across the Australian continent, which if combining with cold fronts approaching from the Southern Ocean, can result in volatile weather. The recent negative IOD event was one of the strongest on record and this is the reason for the large rainfall totals and floods across the south-east of the country.
And now, we're set to see one of the most severe and damaging systems this year forming directly south-west of Kangaroo Island, dropping to a central pressure of 975hPa at its deepest early Thursday morning.
While this low won't reach the requirements of a 'bombing low' (dropping 24hPa in 24 hours) it will still stall and produce a fetch of storm-force SW winds aimed right into the South Australian coastline from Wednesday evening, projecting into the coast Thursday afternoon.
The stalling and strengthening nature of this low is the most worrying development, with damaging winds, large storm swell and coastal inundation due all day Thursday and into early Friday.
Also remembering that due to the inverse barometer effect, where under lower surface pressure the ocean rises 1cm per 1hpa, we'll see tides reaching 20-25cm higher than they normally would. Along with this the storm-force winds will pile up water across the coastlines, causing wide-swept coastal erosion - worst during the late afternoon when high tide is forecast, and as the low tracks towards Adelaide.
With this we'll likely see see the sand dune at South Port Noarlunga eroded further after the floods seen just over a week ago (see our article on South Australia's (sort of) Superbank).
Looking at the potential swell from this system, and the southern Eyre Peninsula, Kangaroo Island's West Coast and the Yorke Peninsula will cop the largest waves with open ocean swells directly off the coast due to reach in excess of 40ft. If the Cape du Couedic wave buoy weathers the storm, the readings probably reach phenomenal heights during Thursday.
The weather, wind and swell should abate steadily through Friday as the low weakens and moves slowly east, but it will take some time for the coast to recover from such a dynamic winter and early spring.
Keep an eye on our Mid Coast and Middleton surf reports and forecasts, plus our surfcams at South Port, Middleton and Knights. //CRAIG BROKENSHA
Comments
2016 has been super active with prolonged westerlies - reminds me of the late 80's and early 90's when it seems we had a decent metro stormy every week.
Almost tempting to do a strike mission just to relive the good ol' days at a bunch of spots between Hallett Cove and North Haven.
Great wrap about the neg indian dipole anomaly craig . Batten down the hatches !
Yeah, it's gonna get pretty hectic over your way. The coastal cliffs and swell will be a sight to see from a safe vantage point Thursday!
Ahh the ex-Adelaidian surfer in me is frothing a little....it's incredible how much fun can be had with a stormy.
I don't think I'll be landing at Adelaide airport 6:30am Thursday ...... Btw Bali has had some heavy down pours over the last few days. Some local lads travelled all the way up from Bingin to Medewi to find so me clean water.
Love these articles and learn something new everytime.
Batten down the hatches Crow Eaters, Henly Beach is going to be pumping.
Who wants a curve ball?
The latest BOM hi-res model (used above and pictured below) and EC have the low centre further north!
This will result in the Adelaide metro beaches missing out on the storm swell, with relatively subdued weather Thursday. Friday will still be stormy though.
GFS still has the low slamming the Adelaide coast.
Either way the Eyre Peninsula is still going to cop it. A very dynamic and tricky system.
And if BPs rigs were in the Bight ??
Totally!
I've never seen anything like it here in S.A, Craig.... Absolutely saturated down here in the south east..... Feelin' sorry for the magpie couple in our backyard tree.. they've got 3 babies in the nest..... Hope they make it through.
The rig would stop drilling obviously
Update Craig?
Oh dear!
That's about as severe as it gets!
OH DEAR
Full zoom earthnull fuck thats a wild looking system
Yikes!
Watching the lightning on the South Port surfcam.. then boom! Offline.
Seems most of Adelaide has also blacked out?
Yeah I'm seeing reports of nearly the whole metropolitan area being without power.
Now Middleton and Knights cams offline too. Seems the apocolypse has finally arrived. Hopefully there's a few waves at Brighton Jetty to go out on a bang with though!
Sky News: "There are reports the entire state of SA is without power."
This is quite beautiful.
Now saying power not restored until 4am tomorrow....comms will become a problem...
Lights are on in the ABC Adelaide studio though....
Yeah listening, they are running on generators.
nick xenophon or do you mean generators ha ha
Hows the superbank gonna hold up ?
Should hold with the low not making a direct impact on the gulf. Worst overnight and early Thursday.
It looks like a tornado which impacted Blyth could of taken down transmission lines causing the outage.
Kinda incredible that the entire state is without power!
Absolutely incredible ...
Trying to understand the synoptics its seems that once the low crosses onto the land it dissipates rather quickly. Is that coincidence or is that this is simply a intense short life storm system?
Not sure on the specifics on why it weakens, probably more so the upper atmospheric setup breaking down rather than how Tropic Cyclones weaken over land due to lack of latent heat energy from the ocean.
Are we saying that one storm has switched off power to all of SA ?
Time to get yourselves a diesel generator.
wow!!!
hope everyone stays safe!!!
That's nuts. Just beginning to sprinkle here, I can see it coming on radar.
had to go and pick up my daughter from the train.it stopped about half. a km. from Marino station.all traffic lights out,rivers running down the road and i couldn't even see anything on the coastline.another 6 hrs. of wind and rain last night and when i look at the news i think i'm one of the luckier ones
Yeah it sounded pretty heavy last night across the state, seeing those transmission lines twisted and mangled is insane!
A great ASCAT image of the low. Some 60kt barbs in there!
The width and length of that fetch is off the hook. Never seen anything like it in Southern Australian waters so close to the mainland.
Shame it's not five hundred or a thousand kays off the coast.
MSLP got down to 972.3 hPa at Neptune Island around 3am.. incredible!
At 3am the previous day, pressure was 1005.4 hPa. That's a 33.1 hPa drop in 24 hours.
Sheepy you still have nne winds
Hows the west coast waters Caml ?
Also at 3am this morning - MSLP at Nullarbor was 1008.5 hPa.
That's a 36.2 hPa pressure difference over ~630km.
Or 1 hPa difference every 17km.
Nuts!
Lovely hand drawn synoptic from this morning, courtesy West Oz BOM.
Image of South Port from Jason Russell, one hour after low tide.
That's almost six hours before high tide.
Yikes!
Jesus.
JR still own that Tom Curren gun ?
CDC max 9.9m @15s this morning - looks like its offline now (unless its another power outage?)
30ft max wave heights at the CdC buoy (probably bigger now) and the surf is almost flat at Middleton.
Keeping in mind that as the crow flies, it's around 200km from Middleton to the buoy. Similar distance as Newcastle to Wollongong.
Imagine if you were looking at the buoy data in a few years time, without knowing the synoptics? You'd assume it was massive across the entire South Oz coast. But it's not the case.
A classic example how buoy data - especially non-directional - doesn't always paint a complete picture.
Can't be a power issue at KI - apparently it runs off a different electricity system, sourced locally (Kane Overall was reporting full power there last night).
Just heard from one of our surfcam hosts today: "The power outage we had yesterday has caused chaos. I only found out this morning we were only running at 43-45hz not 50. Crew can't open their electronic doors".
What a nightmare!
This is absolutely insane! Watch the entire storms life cycle.