A strange formation of clouds was seen in the heavens of Sydney, Australia on Friday. The odd pattern was dubbed a"cloud tsunami," which both frightened and stunned the citizens of New South Wales.

According to Bored Panda, the cloud formation is technically called a "shelf cloud." People who were on Bondi Beach had clearly seen the massive, several-kilometer-long wave of mass stretching across the sky.

A photo posted by The Weather Channel (@weatherchannel) on Nov 9, 2015 at 11:25am PST

The Australian Bureau of Meteorology clarified that the billow was a result of bad weather and warned everyone in nearby areas of upcoming thunderstorms, heavy rains and strong winds. "[The shelf cloud] is created by a cold outflow from a thunderstorm lifting the moist air very abruptly, it is an outflow feature from a thunderstorm," forecaster Christopher Webb told the Daily Telegraph.

"When the rain from the thunderstorm comes vertically down it drags the air with it, it spreads horizontally and forms a gust front and you get the humid air being lifted abruptly from the outflow of the thunderstorm."

A photo posted by Matt Lusk (@mattlusk) on Nov 9, 2015 at 5:15pm PST

The publication adds that the seemingly apocalyptic shelf clouds were a result of the "turbulent weather system." On that afternoon, wild storms hit parts of the country, including the Hunter and the South and Central Coasts.

The Hunter and Central Coast regions then announced severe thunderstorms that produced large hailstones and heavy rainfall, which were predicted to result in flash floods and strong, damaging winds. Forecasters started to worry when storms started to submerge the south of Sydney near Camden.

A photo posted by ABC News (@abcnews_au) on Nov 8, 2015 at 4:27pm PST

Bureau forecaster Mohammed Nadi told Daily Telegraph that the storms reached the greater area of Sydney with strong rains. Meanwhile, the controversial shelf cloud made noise on social media. "People were running from the streets to capture the unbelievable cloud formation," an eyewitness told CNN.

In fact, pictures and videos of the once-in-a-lifetime incident emerged online. "This is a pretty significant one, plus it's been a warm day, a lot of people are out - particularly at Bondi - and this huge mammoth storm just started rolling up the coast and of course social media went atomic," photographer Nick Moir, of the Sydney Morning Herald, told Sky News.

A photo posted by RheeTKD (@masterarhee) on Nov 7, 2015 at 9:48pm PST

Instagram and Twitter users used the name "cloud tsunami" to describe the cloud formation. All the dynamics of the atmosphere came together for a short time. It was a short, sharp event," Mohammed Nabi, a Bureau of Meteorology forecaster told the Sydney Morning Herald

Watch the shelf cloud in a time lapse by In The Now: