Hurricane categories are often misleading, here's how to fix the problem


MIAMI – The consensus seems to be that Hurricane Florence came ashore with Category 1 winds, Category 5 rainfall flooding and Category something-less storm surge. As if “category” is the only word in the English language that can describe the badness level of a hurricane.

Categorizing everything is a nonstarter — a Category 1-5-2 label clarifies nothing. Furthermore, boiling down the forecast severity of the rainfall flooding and the storm surge is tricky, because they both happen to the land because of the storm. They are not features of the hurricane itself.

But there are things we can do to better communicate the risks associated with every hurricane hazard.

Add “wind” to categories and kill the term “major” hurricane

Clarifying the wind-threat piece of the puzzle is easy: Add one word, and get rid of another.

If the National Hurricane Center started ranking hurricanes as Wind Category 1 through 5, eventually it would roll off the tongues of weathercasters, “Hurricane Florence is now Wind Category 4!” It would take some time, but eventually categories and wind would become connected.

Striking the word “major” from the meteorological dictionary would also help free from confusion the discussion of wind speeds and the danger that comes from every hurricane. “Ike was not a major hurricane” will never be a true statement, no matter that it was a (Wind) Category 2 when it demolished the Texas coast and crippled Houston. And, by the way, Sandy wasn’t a major storm, either, using the meteorological definition.

Whoever decided that the word “major” should be used to describe a subset of hurricanes — based solely on their peak winds — did not have public communications in mind. It is time to fix that mistake and refer to the most damaging storms as simply (Wind) Category 3 and above.

To be fair, category confusion was not a factor in the days leading up to Florence’s assault on the Carolinas.

In fact, Hurricane Florence did us a favor when it looked as if it was going to plow into North Carolina as a Category 4 hurricane. Category 4s are great motivators. There is no doubt that many people left the area in Florence’s path because of the Cat 4 fear factor.

The fact that fewer people were trapped in the monstrous flood because they were running from the wind is a happy coincidence, but in no way does it prove the system worked.

Imagine if the forecast is perfect next time: a Category 1 at landfall. More people will stay, and the post-storm trauma will be worse. A better, high-profile way to communicate the flooding threat must be found.

Develop an alert system for extreme flooding risk

At its root, the challenge is that the National Weather Service warns of flooding from heavy rain all the time. Every extra-heavy downpour justifiably begets a flood alert of some sort. So it’s easy to understand why the same old local watches and warnings don’t convey the level of threat that Florence presented.

In the days before landfall, the flooding threat from Florence deserved more than a patchwork of meteorologically correct but otherwise mundane Flood Watch zones. A flood catastrophe was forecast. The alerting substance and style needed to match the danger.

An “extreme flooding risk area” might be an appropriate alert. Whatever it is, people have to intrinsically feel the severity of the situation. And it needs to be part of the National Hurricane Center advisory, along with alerts for the other threats.

Develop an evacuation risk, watch and warning system for storm surge

Storm surge alerts are another ball of string. Few meteorologists can explain why storm surge forecasts presented in local bulletins, National Hurricane Center advisories and on potential inundation maps all show different numbers for the same locations for the same storm. And the meteorologists that understand the scientific underpinnings have trouble explaining why it’s necessary. The science is outstanding, but the communication is a hopeless jumble.

The solution does not entirely reside in the National Weather Service or at the National Hurricane Center. The raison d’etre of storm-surge forecasting is to help public officials order timely and scientifically supported evacuations. The evacuation directives are the bottom line.

In the end, an evacuation order is the storm-surge alert to which we want people to respond.

An evacuation risk, watch and warning system — coordinated through FEMA, local emergency management, the National Hurricane Center and the National Weather Service’s local offices — would put evacuations at the front of the communications process, where it belongs.

On top of all these issues is timing. The Florence cone showed a Category 3 or 4 hurricane approaching the coast five days in advance. But the flooding and storm surge alerts didn’t show up until about three days later. Meanwhile, there was talk of evacuations, with no weather alerts to back them up.

If people are going to be alerted for the wind five days in advance, equivalent risk areas for flooding and storm surge need to be issued on the same timetable. Otherwise, the wind category is always going to lead the discussion, even when it is not the biggest threat.

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