SYDNEY FLOODS, APRIL 2015

Over the past two days, the Sydney, Central Coast, and Hunter regions of New South Wales have experienced very heavy rain, gale-force winds with gusts over 100 km per hour, and waves of more than 10 m in height. Sydney experienced the wettest single day since February 2002, with 119.4 mm of rain recorded in the 24 hours to 9 am on April 21. Meanwhile, Tocal in the Hunter Valley recorded more than 100 mm in a single hour. Sadly, three deaths have been reported from flash flooding at Dungog. Another woman's body has been retrieved from flood waters near the northern NSW town of Maitland, bringing a sad end to a day-long rescue operation today.

The wild weather is due to a so-called “East Coast Low” or “East Coast Cyclone”, which are terms used for low-pressure systems that develop off the east coast of Australia, generally between Brisbane and eastern Victoria.

In 2009, a group at the Bureau of Meteorology painstakingly searched every synoptic chart between 1970 and 2006, looking for all low-pressure systems along the east coast. They identified about 22 East Coast Lows each year. About seven of these each year caused widespread rainfall totals above 25 mm. While lows are most common between May and August, they can occur at any time of year, with about every second April having a low that meets this 25-mm rainfall benchmark. This latest East Coast Low is a severe event, but not a record. In fact, Sydney experiences rainfall above 100 mm almost once a year on average, so this is a normal feature of its climate...

A friend sent me this photograph of a flooded road in Marrickville, a Sydney suburb.

This post is part of the Wednesday Waters meme,
and also part of the Waterworld Wednesday meme,
and also part of the Outdoor Wednesday meme,
and also part of the Wordless Wednesday meme.