Category 5 Beryl: A record-setting and deadly hurricane

The 2024 Atlantic hurricane season has been off to a rare and dangerous start.

Hurricane Beryl is the earliest Category 4 and Category 5 hurricane on record for the Atlantic, developing as a result of primed conditions that favour a very active hurricane season. Those conditions include record setting warmth in the tropical Atlantic waters and a favourable wind environment.

“The current conditions in the tropical Atlantic are more akin to something we’d expect during the typical peak of hurricane season in September,” says Bob Robichaud, warning preparedness meteorologist with the Canada Hurricane Centre.

“This has been a building situation in the Atlantic with record-setting water temperatures extending as far back as the winter before last.”

Only about two per cent of the major hurricanes on record in the Atlantic have occurred in the month of July, giving context to how statistically rare it is have a major storm this early in the season.

Hurricane categories explained

The Saffir-Simpson Scale is a method of rating the intensity of a hurricane based on a maximum one-minute sustained wind.

Developed in 1971 by Herbert Saffir and Robert Simpson, the scale ranges from Category 1 to Category 5. While utilized largely since 1974, the scale has undergone some revisions and updates over the years.

A Category 1 hurricane is declared once the maximum sustained wind speed reaches 119 km/h.

A Category 1 hurricane is declared with a maximum sustained wind of at least 119 km/h and a category five hurricane with a maximum sustained wind of at least 252 km/h.

The risk of wind damage to structures escalates as the category increases. A Category 1 hurricane should cause little wind damage to well constructed structures, though power outages can still be extensive. At Category 5, a hurricane poses a risk of extensive building damage or failure, can cripple power infrastructure for weeks or months, and flatten extensive areas of trees.

Category 5, the top end of the Saffir-Simpson Scale, the maximum sustained wind speed of the storm at least 252 km/h.

The wind speed of a hurricane can be evaluated by a number of methods including dropping a sensor, known as dropsonde, from a hurricane surveillance aircraft. Data from weather satellites can also be used to infer the potential maximum wind speed of the storm.

Shortfalls of the scale

The scale does not account for other hazards posed by hurricanes. Those include magnitude of storm surge, torrential rain, and tornadoes. It is the water hazards with hurricanes that have historically been the deadliest part of the storms. Storm surge in particular, but also flash flooding and mudslides triggered by the rain.