This past hurricane season was an active one, tied with 1969 as the fourth-most active Atlantic hurricane season on record, and included the exceptionally strong Hurricane Dorian. Dorian made landfall in the Bahamas with sustained winds of 185 mph and gusts up to 220 mph, making it a strong Category 5 storm. Category 5 storms on the Saffir-Simpson scale are defined with sustained winds of 157 mph or greater.
An opinion piece in Scientific American suggests that this scale may be inadequate and makes an argument for adding a Category 6 (and even 7!) to the scale—converting Dorian to a category 6 storm.
The article also discusses the difficulty in communicating a hurricane’s threat to coastal (and inland) residents. It notes that the Saffir-Simpson scale that most of us are familiar with does not include storm surge or rainfall information, which for most hurricanes represent the greatest threats. While the National Hurricane Center does provide surge predictions and local weather service offices endeavor to provide detailed maps with relative threat levels from different hazards, it can be difficult to synthesize all this information into an easily-communicated threat level.
This article’s author questions whether we need a new system altogether, and made me think. I’d like to see an index that takes into account how fast the storm is moving (to evaluate rainfall/riverine flooding potential), the wind speed (to evaluate wind loading on infrastructure), and the storm surge (for coastal impacts). I’ll keep thinking about this – do you have any ideas? Leave them in the comments! – Thanks, Beth Sciaudone, DTC Civil Water Resources & Environmental Instructor