'Bomb cyclone' sounds scary but it has a specific meteorological meaning

The use of terms including "atmospheric rivers" and "bomb cyclones" to describe weather phenomena has moved out of scientific journals and into the mainstream in recent years, but meteorologist Cindy Day says there's nothing alarmist about the language.

Day says that when used appropriately, such scientific language is necessary and can help people better prepare for the impact of extreme weather events.

Day says the term "bomb cyclone" has been used by scientists for decades and describes "a low-pressure system that is undergoing explosive cyclogenesis," or the creation of cyclonic air circulation.

WATCH | Why do our weather events sound so scary? 

Does jargon like 'bomb cyclone' help or hinder understanding of weather?

1 month ago

Duration 4:46

B.C. is no stranger to extreme weather — from the atmospheric river over the weekend to heat domes. You might have also heard phrases like polar vortex and bomb cyclone being used by the experts. But why and when did we start using these sorts of descriptions — and when did we stop simply calling it "a cold spell?" Our science and climate specialist, Darius Mahdavi, explains what's going on.

She says terms like "bomb cyclone" and "atmospheric river" can often help paint a picture that allows people to better understand and prepare for various weather systems.

In British Columbia, an atmospheric river originating near Hawaii has long been known as a "pineapple express."

"So, an atmospheric river — right away, people start to think, 'OK, it's a narrow band of moving water,'" Day said. 

"It does give you the sense that this is going to be a steady event and that there's not going to be time for the ground to absorb the rain. It'll continue to rain and eventually cause flooding because of that concentrated rainfall."

In British Columbia, the government called for the creation of a scale to rank the power of atmospheric river events in 2021 in the wake of a devastating system that brought widespread flooding and shut down the Trans-Canada Highway and other key roads.

But Environment Canada said the next year that implementing such a scale for public warnings was premature.

Day noted that she had received "a lot of grief" for using the term "bomb" in relation to meteorological phenomena, with some accusing her of trying to sensationalize weather events. 

"I really believe that if they're used in the proper context, that they're not alarmist," she said.

"As long as the people know that they're getting their information from a qualified source, and that source [or] that person is using the terms correctly and not shouting out 'bomb' every time there's an area of rain coming in, I think it's really important to understand those words and to take them seriously and to know that they're based in meteorological fact, in science."