11th Sep – Warm coasts and old boats

SST update

The most recent sea surface temperature anomaly snapshot across Australia shows the Bight is cool, Coral Sea temperatures are mostly back to average and there’s some warming in the Tasman Sea. In the south west it’s warmed up again near the coast but, further out, there are large areas where the surface is 1-2°C cooler than usual.

However, what really stands out is the continuing warm trend off the Pilbara. A broad area of the North West Shelf is now at least 1°C above average.

The IMOS percentile chart shows the sea surface temperatures all around Broome and Port Headland have been in the 90th percentile for the past week.

Sea surface temperature percentiles, 6 September (source: the IMOS percentile chart shows the sea surface temperatures all around Broome and Port Headland are in the 90th percentile.

The high sea temperatures are not surprising; air temperatures in the north of the country have been record-breaking high. For August, the average maximum temperature was the warmest on record for the northern Kimberley in Western Australia. The outlook for the next few weeks shows little relief.

Australia’s outlook foremperature—the chance of above median maximum temperature for 14-20 September.

Coastal flow

Last month, the East Australian Current began tracking closer to the QLD and NSW coast.

The current is now showing up as a warm anomaly extending to the large warm eddy east of Sydney, and is bringing warm water closer to the coast.

The Tweed Heads buoy measured an increase in temperature on Monday, jumping almost a degree.

The change in current naturally alters the behaviour of the animals connected to it. In the area there have been reports of increased fish activity, bait balls, and whales close to shore. The Tweed Heads buoy is the closest buoy to Greenmount Beach, where the tragic fatal shark attack occurred on Tuesday.

Further south at Bulli, a whale carcass has attracted a large number of sharks and resulted in beach closures.

Whales have been found to use the inner edge of the East Australian Current to navigate their migration. When the current is close to shore, there’s an increased (though still low) chance that they’ll get caught in shark nets. With the OceanMAPS forecast indicating the current will remain close to shore for now, it will be worth monitoring the region for more activity this month.

Out boatin’

Finishing with a good news story, two men in an old boat, without much safety equipment or even a recreational boat licence, went missing last Friday trying to sail from Port Lincoln to Goolwa, triggering the largest search in South Australian history. They were found safe and well when they made contact on arriving at Salt Creek, well outside the search area, hours after the search was called off. 

The 120,000 square kilometre search area, shaded. Pink circles mark start and finish points. Source: SA Police.

Incredibly, they had had no idea that anybody had been looking for them, with one commenting “It was rather large swell, but I felt safe.”

A snapshot of the increase in swell late last week at Cape du Couedic, Kangaroo Island, as the boat began its journey. Source: Bureau of Meteorology.