Northern beaches suburbs cut off after massive ‘tropical’ downpour

The northern beaches suburbs of Whale Beach and Palm Beach were cut off from vehicle traffic by an unusually heavy dump of rain on Tuesday.

A slow-moving storm dumped more than 50 millimetres of rain on the area in the early afternoon.

The torrential rain closed Barrenjoey Road, the only main road to the north, where it meets with Whale Beach Road, north of Avalon. By 5pm, conditions had improved, and NSW Police were directing traffic, allowing motorists to drive in one direction at a time.

After the deluge, locals were warning others to take care on the Bilgola Bends. “I’ve never seen it like that before. Flooding and really dangerous. Take care,” one person wrote on the area’s Facebook page.

There had been some hail, too, to “add to the danger,” another local wrote.

The Bureau of Meteorology’s Edward Medlock said this kind of storm was unusual at this time of year, when there was little moisture in the air. Instead of moving away from the area, the storm appeared to re-form over land, Medlock said.

Medlock, a meteorologist, said Great Mackerel Beach, directly to the west on Pittwater, had received the highest rainfall in the NSW network on Tuesday, recording 42.5 millimetres from 1pm to 2pm.

Over a two-hour period, it recorded 55.5 millimetres of rain, meaning it was classified as significant rainfall, which happens only once in five years, on average. But the deluge was less than the 67.5-millimetre threshold for heavy rainfall, which occurs only once in 10 years, on average.