Do We Need Category 6?

In 1969, seeing Hurricane Camille approach, weather experts used a pile of statistics. Issuing warnings, they referred to gale-force winds, rising tides, and rainfall. When the experts looked back at the response, they said people failed to turn their knowledge into practical action. One report emphasized the confusion.

After, they decided there has to be a better way.

Quantifying Disasters

Today, we give hurricanes a category. Experts have debated a similar system for heat waves.

Hurricanes

Our story starts with a United Nations project.  Their goal was to use structural wind damage as the basis for a hurricane severity scale. The result was a 1 to 5 scale that described what we could expect from wind speeds. Called the Saffir-Simpson Scale, its name partially came from Herbert Saffir:

In 1974, we began giving hurricanes a category based on the Saffir-Simpson Scale. Whereas unanchored mobile homes experienced Category 1 damage, widespread catastrophe characterized Category 4 or above. With Categories 4 and 5, we could expect weeks of power outages, uprooted trees, and blown away buildings.

The Saffir-Simpson Scale climbs a ladder of wind speeds (that have a projected impact):

Heat Waves

Comparable to hurricanes, we can ask about quantifying heat waves. The National Weather Service does have a heat index. Also called the “apparent temperature,” it tells us what the actual temperature feels like. Consequently, a 90-degree reading with high humidity could have an index of 113 degrees.

The question, though, is whether we should take the next step for categorizing heat waves by ranking and naming them. A World Meteorological Association report says no. They worried about contradictory messages that clouded global communication. In an advantages/disadvantages table, they also said the same heat wave can have varying impacts and provide “a false sense of complacency.” Because a heat wave designation applies across national borders to a broad mix of industries, it cannot be adequately characterized.

By contrast, California legislation mandates that the California Environmental Protection Agency create a heat wave ranking system by January 1, 2025.

Our Bottom Line: Statistics

As we know, statistics always have a tradeoff. One number has power and clarity. But it can be misleading, especially when based on debatable components. It leaves us with a slew of questions about heat waves.

We also can ask if the intensifying character of hurricanes warrants a Category 6. Experts worry that a “6” could diminish the significance of Category 5.

My sources and more: Always interesting, 99% Invisible did a hurricane podcast that was particularly relevant. Focusing on quantifying disasters, their discussion took me to this Hurricane Camille report. From there, I went to the WMO analysis of quantifying heat waves and to CNN’s more positive perspective. Continuing along this path, we can conclude with California’s AB2238.

Our featured image displays Hurricane Katrina (2005).