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  • Water is deadlier than wind when it comes to hurricanes.

  • In fact, it causes 90% of the loss of lives

  • related to powerful storms.

  • But when meteorologists talk about a Category 3 system

  • headed their way, that classification

  • just takes wind speed into account.

  • There's no single scale to indicate

  • both how strong and how wet the systems are.

  • In general, we tell people in the meteorological community

  • to hide from the wind, but run from the water.

  • But if we know water can actually cause more damage,

  • why haven't we updated the way we measure hurricanes?

  • Let's take a look back.

  • The Saffir-Simpson scale, going from 1 to 5,

  • measures the speed of sustained winds of a hurricane.

  • It was developed in the 1970s to calculate

  • how much wind can impact property.

  • A storm becomes a Category 1 hurricane

  • when winds reach 74 miles per hour.

  • This kind of speed can damage roofs,

  • sidings, and knock large branches out of trees.

  • Major hurricanes start at Category 3

  • once winds increase to 111 miles per hour.

  • They can cause devastating destruction

  • to well-constructed buildings.

  • And there's a high chance of injury or death.

  • Category 5 hurricanes have winds over 157 miles per hour,

  • and are the top of the scale.

  • These systems can devastate large areas,

  • leaving them uninhabitable for months.

  • But again, this is just from the winds.

  • It doesn't take into consideration

  • the impacts of storm surge and rain.

  • Storm surge happens when winds push water from the sea

  • onto the land, flooding large areas.

  • It's fast, powerful, and can send 10 to 20 feet of water

  • several miles inland from the coast.

  • Hurricane Katrina was one of the deadliest storms

  • to ever hit the mainland United States.

  • But its 127 miles per hour winds

  • meant it was only classified as a Category 3

  • when it made landfall in Louisiana.

  • The water broke the levies protecting New Orleans.

  • And within a day, about 80% of the city was underwater.

  • With Hurricane Katrina in 2005,

  • we really didn't, we didn't have in the collective

  • public mindset the difference between a really large

  • powerful storm and a compact powerful storm.

  • The pictures and the memories of Katrina

  • aren't really about the wind damage.

  • It's mostly about the storm surge,

  • the levies failing in New Orleans, things like that.

  • And even smaller Category 1 systems

  • like Hurricane Dolly, which slammed South Texas in 2008,

  • can leave behind death and destruction for the same reason.

  • For a while, the Saffir-Simpson Scale

  • also categorized storm surge,

  • but it became difficult to communicate

  • the specific dangers of each storm to the public

  • since the threats from water and wind can be so different.

  • So in 2017, NOAA's National Hurricane Center

  • started issuing official storm surge watches and warnings.

  • What's different about the storm surge warning

  • is what's different about the storm surge.

  • It can occur in somewhat different locations

  • than the strongest wind, and at different times.

  • These advisories are key to helping people prepare,

  • even if they're not directly in the path of a storm.

  • But they still leave out potential flooding

  • that could be caused by rainfall,

  • which is a whole other advisory from NOAA.

  • You need to know if your location's going to be

  • impacted by storm surge, or potentially freshwater flooding

  • that occurs from incredible rainfall amounts.

  • Because the time to evacuate, or whatever,

  • isn't when the water is rising into your home,

  • or business. It's beforehand.

  • The Saffir-Simpson scale's historical popularity

  • and basic 1-to-5 format

  • means it's unlikely to go away anytime soon.

  • But there are a few alternatives out there,

  • like the Hurricane Severity Index, owned by StormGeo,

  • a private weather intelligence company.

  • It uses a 50-point scale that measures

  • the size of a hurricane and the intensity of its winds.

  • Each component gets 25 points, to be more precise.

  • Size is very important because it matters

  • for the aerial extent of the impact,

  • how much time a hurricane's going to hit you.

  • Things like storm surge, wave heights,

  • rain amounts are greater.

  • The HSI can also help people compare storms

  • they might have already experienced

  • to get an idea of what to expect.

  • The index would have placed Katrina's damage potential

  • in line with a Category 5.

  • While its intensity was only 13 out of 25,

  • its size was a 23 out of 25.

  • But media outlets rarely use the index as a tool,

  • relying mostly on the Saffir-Simpson scale.

  • Most journalists include NOAA's storm surge advisories

  • in their reports as well.

  • But most of the attention around a storm

  • still seems to center on the category it falls under.

  • Atlantic hurricane season goes from

  • June 1 to November 30.

  • And 2020 has been a particularly active one.

  • With things like climate change and a warming world,

  • hurricanes are more, there's going to be

  • more intense hurricanes making landfall.

  • NOAA predicted 19 to 25 named storms.

  • And as of September 21, we've already had 23.

  • That's already beaten last year's 18 named storms,

  • which was also above average.

  • And even as weather forecasting has been

  • refined and improved, experts say there's no substitute

  • for always being ready for a storm to hit.

  • We have to make sure everybody understands

  • that the forecasts aren't perfect.

  • And sometimes the storm does something

  • not quite what we forecast,

  • and you really need to be prepared.

  • Most importantly, follow the advice

  • of your local emergency management officials.

Water is deadlier than wind when it comes to hurricanes.

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What’s Wrong With The Way We Measure Hurricane Intensity

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    林宜悉 posted on 2020/10/23
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