There has been some extreme weather in Australia recently, as parts of the country have broken records for the wettest November on record. The media have been reporting that “rain bombs” have hit the country due to the feeling that there has been an explosion of rain.
But what are rain bombs and when do they occur?
What are Rain Bombs?
Rain bombs occur within a thunderstorm when hot, dry air is sucked into the storm. The air temperature gets colder very suddenly and that cold air can then drop very quickly, unleashing large amounts of rain onto the ground below. They often occur during hot and humid summertime afternoons.
The term rain bomb is more often used in the media than by meteorologists, but it normally describes a microburst of wind and rain that is concentrated over a specific area. There are both wet microbursts –– like we’ve seen in Australia over the past week –– and dry microbursts.
These microbursts often only last 5-10 minutes, but with fast-moving winds that can reach a maximum of over 200km/h, they can cause devastating damage.
What is Happening in Australia?
While it is currently summer for Australia in the Southern Hemisphere, heavy rainfall and thunderstorms have been lashing the New South Wales area in particular. Sydney had 50mm of rain on Sunday with further thunderstorms expected.
Another rainy weather system is heading our way, with Flood Watches now in place for most of eastern #Victoria.
Further details can be found in the latest Severe Weather Update video. Know your weather, and know your risk! 🌧️
Forecasts: https://t.co/LYU4Ldskfm pic.twitter.com/KNaQLxN264
— Bureau of Meteorology, Victoria (@BOM_Vic) November 23, 2021
In the Queensland town of Balberra, a giant rotating rain bomb circulated across farms and paddocks and drenched the area with rainfall. Other areas in Queensland are at risk of developing ‘supercell thunderstorms’.
These types of thunderstorms have a rotating updraft (upward moving air). They are the least common type of thunderstorm, but they produce severe weather, including high winds, large hail, and tornadoes.
The Bureau of Meteorology in Australia has now declared that a La Niña has developed in the tropical Pacific. During La Niña weather occurrences, warm water is pushed towards the western side of the Pacific, including Australia and Asia, which leads to more evaporation and more rainfall over Australia.