Is it time to rethink how we measure potential hurricane threats?

Boston Globe

5 days ago

That's because the Saffir-Simpson Scale only takes into account a hurricane's sustained wind speeds, and not other potentially deadly hazards, such as storm surge, a storm's duration, spawned tornadoes, as well as flooding and the amount of rainfall a hurricane is going to unleash.
The Saffir-Simpson hurricane scale shows five categories for hurricane strength.
Boston Globe
Let's look at some examples over the years:
Hurricane Irene
— Think about the remnants of Hurricane Irene back in 2011, which created catastrophic flooding across portions of New York and New England, especially in southern Vermont and New Hampshire. We had already had a wet summer that year, and the rain from Irene, which wasn't even a hurricane by the time it reached New England, left behind more than a billion dollars' worth of damage.
People help a Department of Natural Resources worker whose truck became stuck on a washed-out Surf Drive in Falmouth, Mass., during Hurricane Irene, on Aug. 28, 2011.
Bill Greene
A car tries to plow through a flooded Surf Drive in Falmouth during Hurricane Irene on Aug. 28, 2011.
Bill Greene
Hurricane Florence
— On Sept. 14, 2018, Hurricane Florence made landfall around Wrightsville Beach, N.C., as a Category 1 storm. But it wasn't the wind that was the major contributor to this deadly storm that caused $24 billion in damage, but the five-day rainfall totals of 20 to 50 inches across eastern North Carolina. That rain would spread inland, creating mudslides and into the mountains, causing additional flooding.
Hurricane Harvey
— Harvey, which impacted Texas in late August 2017, brought over 60 inches of rain to two locations near Port Arthur, Texas. This was the heaviest rainfall ever recorded in the U.S. from a tropical cyclone, and although the storm was a formidable major hurricane when it came on land, it was not the wind that was the biggest contributor to the $128 billion in damage and the death of 89 people. It was the freshwater flooding from all that rain.
A list of the seven costliest hurricanes on record.
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Storm surges, also not considered part of the Saffir-Simpson Scale, range from 4 to 5 feet with Category 1 storms to over 19-foot surges with a Category 5. However, just as important factors are whether or not a storm strikes at high tide, the particular location of landfall, and the slope of the shelf underneath the water, as well as whether the storm is moving slowly or quickly.
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Storm surge from a head on landfall will be amplified, resulting in extensive damage to property while being life-threatening.
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Human-induced climate change has produced more warming and is leading to more heavy rain events. Attribution science informs us that these hurricanes, which have produced such unusual amounts of flooding rains, were more than likely supercharged by the greenhouse gases we've added to the atmosphere. Homeowners, emergency management personnel, as well as insurance agencies would benefit from a more comprehensive scale than the Saffir-Simpson one predominantly in use today.
Eventually, a hurricane will strike New England again (our last one was Bob in 1991). It would be useful for the public to have a scale that foretold the possible impacts of such a storm because, no matter what the category, there's a lot more than wind that can impact all of us.
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