Hurricane Florence recently dumped between 23 to 33 inches of water on areas of coastal North Carolina. Mandatory evacuations of the Carolina coasts took place before the storm hit, and river flooding has caused evacuations in more inland areas. The damage associated with Florence has been called catastrophic and devastating.
But Florence was “only” a Category 2 storm at landfall.
The Saffir-Simpson scale assigns tropical systems a category based on wind speeds, as shown in this table:
Many Americans, especially those who live near the Atlantic and Gulf coasts, are familiar with this scale, and assess the danger of a storm based on its category. A Category 4 or 5 storm causes much more alarm than a Tropical Storm or a Category 1 hurricane. So understandably, when Florence went from a Category 4 to a Category 2 as it approached the US, many people believed that the storm had been overhyped or poorly forecasted, and that it wouldn’t be nearly as bad as meteorologists were claiming.
Therein lies the problem with the Saffir-Simpson scale. The scale is only based on wind speed, with no regard for rainfall, flooding, or storm surge. These were the true threats associated with Florence, and with 2017’s Hurricane Harvey, which did much of its damage as a Category 1 hurricane and a tropical storm. Yes, winds are a major component of a hurricane and can do a lot of damage. Water, however, is more dangerous than wind. Flooding destroys homes and the personal items within them. Moving floodwater, especially powerful storm surge, can sweep away people, cars, even homes built close to the shoreline. Trees in wet soil are more likely to be uprooted and fall over, crushing buildings. Mudslides can occur in hilly or mountainous terrain.
Between Harvey and Florence, it has become clear that a new, more detailed hurricane classification system is necessary. In the meantime, broadcast meteorologists and the public alike must remember to look beyond a storm’s category. Just because a storm is a Category 1 doesn’t mean it won’t bring large, destructive amounts of water with it.
It is important for water impacts to be better communicated as part of hurricane coverage. Perhaps a new scale will be developed in the future. In the meantime though, make sure to pay attention to rain totals and expected storm surge should you find yourself in a hurricane situation.
©2018 Meteorologist Margaret Orr
Photo Credit: NOAA/NESDIS https://www.nesdis.noaa.gov/content/hurricane-florence-nears-east-coast
Rainfall total source: https://abcnews.go.com/US/hurricane-florence-numbers-latest-power-outages-rain-totals/story?id=57819104