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Hurricane strength is more than just wind speed - Here’s why

Katrina was massive which helped contribute to its insane storm surge.
Katrina was massive which helped contribute to its insane storm surge.(NWS)
Published: Aug. 27, 2021 at 7:40 PM EDT|Updated: Aug. 27, 2021 at 8:12 PM EDT
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(WHSV) - Hurricanes have their categories based on wind speed but that’s not the greatest impact of a hurricane. Storm surge creates the biggest impact.

WHAT IS STORM SURGE?

Storm surge is when water rises to abnormally high levels due to a storm. Almost half of deaths caused by hurricanes come from storm surge. High winds are certainly a fuel for powerful storm surge but whether the storm is a Category 1 or Category 5, that doesn’t define how powerful storm surge will be.

HOW DOES STORM SURGE HAPPEN?

Winds at the level of a hurricane are so powerful, water gets pushed ashore due to the cyclonic flow of a hurricane. Areas of low pressure have winds that rotate in a counter-clockwise motion. This means just to the right of the center of the storm is going to be where the strongest onshore push is in most cases. Areas on the left side of a hurricane still get storm surge but not as bad as the right side with most hurricanes that hit the United States. Wind pushes against water on the weak side. Sometimes a hurricane can be so powerful that water gets pulled out to sea versus pushed on land.

WHAT LEVEL STORM SURGE IS CONSIDERED DEADLY

Any storm surge can cause troubles at any level but once storm surge gets to a least 6 feet, it becomes life-threatening. There are many factors that contribute to storm surge including strength of low pressure, the speed of the storm, and the angle that the storm hits the coast.

WHAT DOES IDA PRESENT?

As of Friday evening, Hurricane Ida is expected to make landfall in Louisiana as a category 4 storm. Winds are certainly going to cause widespread destruction considering maximum winds in the hurricane will be at least 130 mph. 10 to 15 feet storm surge is expected for eastern Louisiana, including New Orleans. This means we are talking about storm surge that could be 2.5 times the height of which storm surge is life-threatening. When storm surge gets above 10 feet, you are talking about storm surge reaching the most destructive of hurricanes.

WHY DOES THIS MATTER?

Hurricane Katrina is considered as one of the most powerful hurricanes to ever hit the United States but Katrina was only a category 3 at landfall. The variable that really caused Katrina to be so impactful was due to storm surge above 25 feet! Katrina was a category 5 at one point, and that can be an indicator of how far hurricane force winds extend from the center. A larger wind field would contribute to more widespread storm surge. If Ida were to hit category 5 strength before landfall, it will be a powerful hurricane regardless of what category the hurricane falls under.

We will keep you updated on how this storm materializes. Click here for our latest updates on Hurricane Ida.

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