Wind is not the only threat in modern hurricanes

The insurance industry faces significant challenges in covering catastrophic risks, especially as climate change causes more extreme weather events. With premiums on the rise and exclusions on the rise, the need for an accurate assessment of these risks is more important than ever. The Saffir-Simpson Hurricane Wind Scale has long been a staple of hurricane assessment, but in today’s world, its focus on wind alone is proving dangerously incomplete. The real killer, as we’ve seen time and time again, is water, both through storm surge and flooding. It’s time to rethink the system, and that starts with refining how we categorize hurricanes, not just by wind, but also by the water threats that cause the most destruction.

Why the wind is beatable

Storm damage, while dangerous, is something we have learned to mitigate. We have seen advances in building codes, structural designs and roofing systems that can significantly reduce the impact of wind. A great example is FM Sheet 1-29 roof deck attachment, which provides detailed instructions for above-deck roof components designed to withstand extreme wind forces. Building codes, such as those enforced in Miami-Dade, and the use of materials such as Lexan windows, show that we have designed many solutions for wind resistance.

The wind can only blow so fast and hard. Sure, it can destroy poorly constructed buildings, but modern engineering has leveled the playing field in many cases. The three little pigs were right – build strong enough and you can beat the wind. But no amount of brick can hold back the relentless force of water. Storm surges and flooding are the real threats of modern hurricanes and are much harder to insure and predict. Noah and Gilgamesh, despite their best efforts, could not stop a flood, emphasizing the relentless and unstoppable nature of water.

The deceptive nature of the Saffir-Simpson scale

Here’s where the Saffir-Simpson scale falls short:

1. No consideration for storm surges: The scale does not account for storm surge, which is responsible for nearly half of all hurricane deaths. Hurricane Sandy (Category 1) and Katrina (Category 3) wreaked havoc not because of their wind speed, but because of the storm surge and flooding that followed.
2. Ignore the potential for rainfall and flooding: Flooding from prolonged rainfall can be catastrophic, as demonstrated by storms like Hurricane Harvey in 2017. Harvey was only a Category 4 when it made landfall, but its slow-moving nature caused some areas to dump more than 60 inches of rain, which leading to unprecedented flooding. .
3. Duration and speed of the storm: A fast-moving Category 5 hurricane could pass quickly, limiting its overall damage. On the other hand, a slow-moving Category 1 storm that lingers over an area can drop enough rain to cause catastrophic flooding. The Saffir-Simpson scale does not take into account the duration of the storm, which can drastically change its impact.
4. Underinsured flood risk (personal and commercial): Flood coverage is typically excluded from both standard homeowners insurance policies and many commercial property policies. When people focus only on wind, they often neglect to purchase the necessary flood insurance, leaving them catastrophically underinsured. Commercially, businesses can be devastated by floods, but many are not adequately covered due to exclusions or limitations in their policies. This oversight results in massive uninsured losses that can cripple entire communities and industries after a major hurricane floods.

A Better System: Refining the Hurricane Rating System

We need a more comprehensive scale that takes into account not just wind speed, but also storm surge, precipitation potential, and storm movement. Rather than creating an entirely new system, I propose that we refine the current system to honor the victims of devastating storms and ensure that their suffering contributes to future safety. Let’s call it the “Helene-Flood-Linger Scale”—an expanded framework that builds on the Saffir-Simpson scale by introducing additional values ​​to reflect the full potential for damage.

The Helene-Flood-Linger scale would measure:

1. Wind category (V): Retains Saffir-Simpson wind speed classification.
2. Flood risk (F): It assesses the flood potential of the storm based on projected rainfall and water volume accumulation over a given area.
3. Risk of storm surges (S): It measures the expected height and magnitude of storm surges, especially in coastal regions. This is essential to anticipate the most destructive aspect of a hurricane in terms of fatalities.
4. Duration Modifier (D): Recognize how long the storm will affect a region. Slower moving storms would receive higher scores on this factor because they allow more time for precipitation to accumulate and sustained damage.

Hurricane Helene’s score and comparison to a faster Category 5 storm

To demonstrate how this refined system works, let’s apply it to Hurricane Helene, which made landfall in Florida on September 26, 2024, and compare it to Hurricane Wilma (2005), a faster-moving Category 5 storm that caused less deadly floods:

• Hurricane Helene (2024):
  • Wind category (V): W4 – Helene made landfall as a Category 4 hurricane.
  • Flood risk (F): F5 – Helene caused catastrophic flooding throughout the Southeast due to prolonged heavy rains.
  • Risk of storm surges (S): S4 – Helene produced powerful storm surges in the Big Bend area of ​​Florida, amplified by rising sea levels.
  • Duration Modifier (D): DSlow – The storm persisted, allowing massive accumulation of rainfall that exacerbated flooding far inland.
  • Helene’s score: W4/F5/S4/DSlow
• Hurricane Wilma (2005):
  • Wind category (V): W5 – Wilma was a Category 5 hurricane at peak.
  • Flood risk (F): F2 – Although Wilma caused some flooding, it moved quickly, reducing rainfall.
  • Risk of storm surges (S): S3 – Wilma produced moderate storm surge, but nothing compared to the storm surge damage in slower storms like Helene.
  • Duration Modifier (D): DFast – Wilma’s rapid movement limited damage from rain and storm surge.
  • Wilma’s score: W5/F2/S3/DFast

The comparison shows that although Wilma was a Category 5 hurricane, its faster movement resulted in less severe flooding and storm surge, making it less deadly than Helene, which persisted and caused widespread flooding. despite being a lower wind category storm.

Flood: The uninsurable elephant in the room

Flood risk is notoriously underinsured, especially compared to wind damage. While storm coverage is a standard part of most home and commercial insurance policies, flood insurance is usually excluded unless specifically added through programs such as the National Flood Insurance Program (NFIP) or private commercial policies. This has left a large unaddressed gap in coverage for both individuals and businesses. As the frequency of slow-moving, heavy-water storms increases, this gap will only become more dangerous.

Floods are inherently more difficult to insure because they affect larger areas and often result in total losses for entire communities and businesses. Unlike wind, which only affects certain buildings or regions, floods can inundate entire cities. This widespread, correlated risk makes it difficult for private insurers to effectively spread flood risk, particularly in high-risk areas where climate change is increasing the frequency of extreme rainfall events.

Why the Helene-Flood-Linger scale matters

The Saffir-Simpson Scale’s overemphasis on wind has made it easier for the public—and even insurers—to underestimate the real threats posed by hurricanes. By improving the current system and adopting the Helene-Flood-Linger approach, we can improve both public safety and insurance preparedness. Here’s why this matters:

• For insurers: The refined scale would enable more accurate risk pricing, helping insurers better understand not only wind exposure but also the much larger threat of flooding and storm surges. This could spur more take-up of flood insurance policies, reducing the dangerous coverage gap, particularly in the commercial sector.
• For the insured: A broader understanding of hurricane risk could lead more people and businesses to purchase flood insurance because they will better understand that even a low-level storm can be devastating if it brings heavy rain or storm surge.
• For risk management: From a risk management perspective, focusing on water versus wind risks is crucial. Flooding is what will continue to ravage the southern US, and we need better tools to design against that risk, just as we did with wind through measures like FM Global’s roof insurance standards.

Conclusion: Refining the risk stabilization approach

We need to move beyond wind-only assessment of hurricanes and recognize that the real dangers lie in the water. The Helene-Flood-Linger scale provides a more complete and accurate method of assessing hurricane risks. By recognizing the importance of floods and storm surges, we can better protect both policyholders and insurers.

Along with this, I have long advocated for a government-backed catastrophic risk program to help stabilize insurance markets. This would allow us to spread risk across a wider portfolio of exposures – including floods, fires and pandemics – ensuring that future generations are better protected from the mega-risks of our time.

TOPICS
Catastrophe Natural disasters Hurricane