What is a bomb cyclone?
A bomb cyclone — one that signals that something is about to go off — is the combination of three words of the name of our meteorological system. The term was first applied to the weather event in 1999, and the accompanying statement that describes the winter storm, notes that “it has the wind speed potential of a bomb.”
Bombogenesis is a meteorological term used to describe the rapid increase in air pressure, which is measured as “bomb” in the system. A pressure drop of 25 millibars or more in 24 hours — known as bombogenesis — has been recorded more than 100 times. A slightly more streamlined-sounding gauge, cyclogenesis, uses the same measurement.
Bombogenesis caused a storm system that affected Alaska and the Pacific Northwest to cause coastal flooding and snowfall to be nearly 15 feet (five meters) in height.
In the United States, bombogenesis has caused extreme wind damage, and subsequently powerful floods that cause millions of dollars in damage each year.
After the scale was introduced, 38 meteorologists across the country launched the Bombardier Hurricane Trail Twitter feed, where they are monitoring track maps, cell phone images and Twitter feed for extreme events. The data has already been documented in such record-breaking storms as Irma and Category 4 Maria in 2017, Emily in 1991, and Hugo in 1989.
We chose the name “bomb” as a moniker because the correct noun, bombogenesis, relates to its sparse occurrences. If the seasonal bomb — the time of year when severe storm (explosive cyclogenesis) outbreaks have historically been recorded in the USA — were to occur this winter, then “bombogenesis” would be the name most often mentioned.
The meteorologists behind the Twitter feed prefer to reference the terminology rather than use a technical term. This is because the storms themselves do not actually “drop bombs” but can make such phenomena appear. Meteorologists are now debating whether the term should be maintained and whether it has particular meaning.
Most likely, the usage of “bomb” to describe a system will not change because of social media. And the term will probably continue to be used often, particularly during extreme weather events.
How strong are the hurricanes of 2017?
The evolution of Hurricane Irma from a low pressure system several hundred miles off Cuba at 8am EDT on Wednesday (4am BST on Thursday) to a record-breaking category 5 hurricane that made landfall in Puerto Rico (where it also recorded record-breaking rain) on September 10 was fueled by a 500 mb (1,930 ft) tropical storm surge, which reaches between 4 and 6 meters (14-21 feet).
Category 5 hurricanes are capable of sustained winds of 180 mb and above, and Irma at its height reached that level.
Category 5 hurricanes occur about once every six years. They are not all together so powerful as to produce a complete catastrophic storm like Irma and her team, and not all are all together so far east.
According to the National Oceanic and Atmospheric Administration, on average, we see only one category 5 hurricane/tropical storm in the Atlantic Ocean every 36 years.
What could trigger a super storm?
Devastating damage caused by a low pressure storm reaching peak pressure or within a few hundred miles of that point.
Depending on the intensity of the event, we could see a day or more, or a day and a half, of intense high-end hurricane status. The greatest threat is in the North Atlantic and Gulf of Mexico during October and November, and in other regions during January and February. At that time, our forecasting systems typically become more and more complicated.