The nightmare hurricane scenario

Sorry, but we have to think about it.

Eric Berger, meteorologist, Space City Weather editor and senior space editor at Ars Technica, said when it comes to hurricanes there are three principal threats to worry about: storm surge, winds and rainfall.

“Typically, with a hurricane you might get one or two of these threats in a particular area,” Berger said.

Ian is different though.

“The reason I say this is a nightmare storm is because for a sizable chunk of Florida it brought all three threats,” Berger said.

He said it is absolutely possible for this kind of storm to hit the Houston area.

“The odds of it happening in any given year are pretty low — probably one in 100. But absolutely it could happen in any given hurricane season,” Berger said.

Surges generally only affect coastal areas or areas within 10 to 15 feet above the water’s surface level. In Houston, those would be places like Galveston and Seabrook, Berger said.

Unlike storm surges, wind can have a wider effect. Wind damage can extend 100 miles inland in the Houston area, Berger said. He noted Hurricane Ike in 2008, when winds were enough to take down the power grid for about two weeks.

For Ike, he said there was a fairly large storm surge along the coast and there was some wind damage, but inland rainfall wasn’t a major issue. For Harvey, he said there was not much wind or storm surge issues in Houston, but there was about 50 inches of rainfall. Houston has yet to see a triple threat like Ian with a damaging storm surge, powerful winds and heavy inland rainfall.

Berger said a storm like Ian would be the worst case scenario for Houston.

“It would really change our community forever,” he said.

He said the immediate impacts would be devastation to parts of Galveston island, Bolivar Peninsula and coastal communities, along with wind damage at least up to Interstate 10. Wind damage would rip roofs off buildings, knock trees down and cause power outages lasting weeks to months. A storm surge threatens to cause environmental catastrophe since many chemical facilities along the Houston Ship Channel are only built up to about 15 feet, meaning there could be facility flooding with toxic leakages in the environment, Berger said. All of this would amount to hundreds of millions of dollars in damage.

“It would be very difficult for this population to come back as vibrant as it is now,” Berger said.

We hope that the long-awaited Ike Dike will help mitigate the effect of a large storm surge. Wind and rain, there’s only so much we can do and most of it is in planning and construction – engineer buildings to withstand high winds, and don’t build things in areas prone to flooding. Maybe there’s more than that, but it feels like mostly hope to me. And if something has a one percent chance of happening in a given year, then over a fifty-year span the odds it will happen at least once are about 40%. Not the most comforting thought.

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7 Responses to The nightmare hurricane scenario

  1. C.L. says:

    Re: “And if something has a one percent chance of happening in a given year, then over a fifty-year span the odds it will happen at least once are about 40%. Not the most comforting thought.”

    @Kuff, I don’t think it (the math) works like that. If there’s a 1 in 1,000 year chance a Cat 6 (for example) hurricane will hit Galveston, and in 2022 one does not, then in 2023 the odds are still 1/1,000, in 2024 the odds are 1/1,000, in 2025 the odds are 1/1,000. The odds don’t decrease as time progresses.

  2. Ross says:

    C.L., the 40% chance Kuff mentioned is not for a single year. It is for a 50 year period where each year has a 1 in 100 chance. If you look at each year in isolation, you are correct, but if you look at a period, the odds change.

  3. C.L. says:

    @Ross… I don’t think that’s the case. If you flip a coin, there’s a 50/50 chance you’ll get heads. Flip it again, 50/50 chance. Flip it again, 50/50 chance. By the tenth flip, you still have the same odds…50/50. The ratios of heads to tails ‘achieved’ may change by the tenth flip, but the odds don’t change.

    In your scenario, the odds don’t change from 1/100 to 1/099 to 1/098 to 1/097 etc., just because time has progressed….that’s why you can can multiple 1-in-100 year climate events in the same year.

  4. Donovan says:

    C.L., the odds don’t change any given year, but the overall likelihood that the event will occur increases as time goes by and you have more chances. To use your example, you could flip a coin 10 times and never get heads, but it wouldn’t be very likely. You would be smarter to suggest cheating than you would to suggest that this final outcome has a 50/50 chance of happening 😉
    I found a great explanation here if you want to see calculations:

  5. Joel says:

    CL – they don’t call it a “100 year storm” because there is a 1 percent chance of it happening every hundred years. if your reasoning were correct, it would make exactly the same amount of sense to call it a “thousand year storm” or a “one year storm.”

    type less, think more.

  6. The math for this, assuming a 1/100 chance each year and that each year is independent of the other years: The chance of a 1% event happening at least once in a 50-year span is 1 minus the chance of it NOT happening over that time period. The chance of it NOT happening in a year is 0.99, so multiply that by itself fifty times. In other words, (0.99)^50. That’s about a 60% chance, so the chance that it DOES happen at least once is 40%.

  7. C.L. says:

    To keep beating this dead horse….

    By this logic, in five years, we’ll no longer hear the term “1 in a 100’ or ‘1 in a 1,000 year storm’ right ? It’ll be ‘1 in a 95’, or ‘1 in a 995 year storm ?

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