Save the Saffir-Simpson Scale

The National Hurricane Center is making a big mistake. This year, they are removing the storm surge levels from the Saffir-Simpson Scale. The problem is not the Scale, but how we use it.

When Herbert Saffir and Bob Simpson introduced their hurricane intensity scale to the public in 1975 it ranked storms based on wind speed, with air pressure and storm surge values assigned to each category. A simple scale ranging from one to five, it took a complicated storm and made it easy for the public to understand.

Most of the time it worked, however, there were a few exceptions. Last year, Hurricane Ike had category two winds when it made landfall in Galveston, but Bolivar Peninsula was swamped a storm surge usually seen with a category four hurricane. Despite frequent warnings of a deadly storm surge, some folks assumed the storm wouldn't be "that bad" because it was "only a category two storm."

To eliminate any confusion in future storms, this season the National Hurricane Center has removed all references to storm surge from the Saffir-Simpson Scale.  It's an experiment and if it's approved the change will be permanent.  There is also talk of creating a second scale just for storm surge.  Others want to get rid of the current scale entirely and create something completely different that would rank the total destructive power of a hurricane.

I think this is a big mistake. The Saffir-Simpson Scale works. Leave the scale alone but rank storms based on wind speed OR storm surge, whichever is the greater threat.

For example, in Hurricane Ike we had 100 mph winds but a 15-20' storm surge.  In this case, surge trumps wind, therefore it would have been ranked a category four storm. Not one person would have stayed on Bolivar Peninsula if they had heard a massive category four hurricane was going to make a direct hit.

Exploring other options

Completely eliminating the Saffir-Simpson Scale destroys all our hurricane records and forces the public to learn a new scale. We have more than 30 years of experience using the old scale. Furthermore, we wouldn't be able to compare today's storms with past storms. Most people can quickly recall that Alicia was a category three, Carla was a four, Ike was a two but should have been a four, etc.

Adding yet another scale only adds to the noise. Think about how many numbers we throw out now during hurricane coverage. There's the latitude/longitude location, the wind speed, the gusts, the pressure, the forward speed and the direction. Then there's the tropical storm force wind speed probabilities, the hurricane force wind speed probabilities and coming soon, the storm surge probabilities. Each of these is different for every location along the coast...and all of this changes continuously every few hours over a period of several days! Do we really need another number to add to the mix?

Every year I attend work sessions and discussion groups at the National Hurricane Conference and we always talk about what didn't work the season before. Inevitably it comes down to the public not understanding the threat. To that end, every year the National Hurricane Center throws us more data, more numbers and therefore more noise.

I'm all for data, but at some point we have to consolidate this mountain of information into something a little more digestible. It might not be perfect, but we know the public understands the Saffir-Simpson Scale: category one is a small storm, three is big and five is the worst. These simple numbers prompt people to take action. Nobody is going to make a decision on whether to board up their windows based on the wind speed probabilities.

That's why I believe we need to keep the Saffir-Simpson Scale and rethink how we use it: rank storms based on wind speed OR storm surge, whichever is the greater threat.

What do you think?

Two weeks after originally posting this blog article, I sent an email to Bill Read, Director of the National Hurricane Center so he could read your comments below.

While the comments section on this blog post is now closed, you can email your ideas directly to the National Hurricane Center using the link toward the bottom of this webpage.

Comments

[Justen Simpton]

Once again, hindsight.
Thank GOD for you guys (weather pros) and we will not let this stumbling block inhibit our trust in you.
In other words this brings no defeat!

[Shreela]

I commented on this post earlier, but didn't fully understand the "OR whichever's worse part", but Tim explained it again in the 2nd related post:

"change how it is used: rank hurricanes based on the wind speed OR storm surge, whichever is the greatest threat.

"Using this method, Hurricane Ike would have been ranked a category four hurricane based on storm surge."

I will explain why I think Ike as a Cat4 would have been stupid, and caused another Rita Evac mini-disaster:

I live in SE Houston, in Zone C, which is only mandatory evac for cat4+. I am well above sea level and did not get any water in my home during Ike.

But if Ike had been rated a cat4, our entire Zone C area would have been mandatory evac for no other reason than this new proposed method of EITHER/OR.

Need I remind ANYONE that more people died in Rita's evacuation than the area that Rita actually struck?

SURGE is for people close to the coast and large-connected waterways.

WIND is for people further inland.

With as much technology as the weather folks have, and most have very high degrees, I find it VERY difficult to believe that having BOTH surge and wind categories to be too difficult, especially when the occasional weird storm like Ike would cause unnecessary evacuations.

We need BOTH, not either/or.

Thank you.

RESPONSE from TIM HELLER: Good point. Thanks for sharing your comments.

[Justen Simpton]

The majority of the public does not use this scale. We watch our prefered local news station or the weather channel and make an evacuation decision based on the info they give us. You would think that we would still be able to be given storm surge potentials and estimations based on central pressure and wind speed regardless. Now if this pointless, rediculous infiltration of a dying world system headed towards legalism prevents Dr. Steve Lyons and the channel 13 weather team from giving us sound advise, then there is a problem.
The shoulda woulda couldas are always seen through hindsight.
Y E S lots of people died in the 1900 storm because they were not informed. Weather men and women, do the best with what you have. Thank GOD for technology and always be praying.

RESPONSE from TIM HELLER: Lots of people died in the 1900 storm because there was no seawall along the front side of the island, protecting them from the storm surge which washed over the entire island.

[Matthew Thomas]

I agree with Tim, yall shouldn't get rid of the Saffir-Simpson scale. What Tim suggests would work and nobody would hve to learn a new scale. If we would of put more pressure on telling people how strong Hurricane Ike's storm surge would of been, maybe a few more people would of lived, maybe peoples personal belongings wouldn't have been destroyed or lost forever. So say if another Ike comes along, Tim's idea would save more people, and instead of having a category two coming there way they would have a category four, and they would listen and leave town.........Think about it.

[MJ]

I agree with your proposal that the rank be based on wind speed or storm surge, whichever presents the greater threat.

[Paula]

I was at the Hurricane Preparedness Workshop at the Pasadena Convention Center last night and I agree with you totally, Tim. I was confused when I heard Hurricane Ike was a Category 2 storm but the death toll was going to be outrageous if people chose to stay put. It didn't make sense until I heard you explain it last night. Evething about the storm should be taken into account and the greater threat should determine the category of storm. Please, no more new data to learn. Just improve on what is already available.

[in La Porte]

I don't completely agree with you. I agree 100% that the NHC must keep the Saffir-Simpson numberic scale because everyone is so accustomed to it. My idea is adding to it with another number to indicate the predicted storm surge. It would not have to be limited to 1-5 either - let it reflect the highest predicted surge - that should get folks attention. An example would be Ike: 2.18. 2 for the winds, 18 for the surge.

[Lindsay]

I agree, and I like your either/or approach. People are familiar with this scale, but the approach isn't working. That doesn't mean throw out the scale, but rather adjust the approach so the scale does work. However, taking the storm surge out of the equation isn't the answer. It would be much more prudent and less dangerous to take your approach, measuring based off of the greater threat.

[Gene Carter]

I totally agree with you, Tim. Keep the system we have, but tweak it to categorize by the storm surge or wind speed, whichever is greater. Too much data is just too hard to digest and keep up with.

[L.A. Thompson]

I think removing the storm surge component only diminishes the level of critically important information. Tweaking the information by adding to it is a better answer. Today's technology would allow us to incorporate either a second number, letter or combination to indicate not only wind but storm surge, possibly resulting in a decimal number, similar to the Richter scale, for seismic energy released by an earthquake. This could automatically indicate the presence of multiple levels of threat which could be broken down into it's component parts and defined for the laymen by meteorologist. Of course NHC would need to release the component numbers simultaneously. I believe the average layman could handle the additional information. We shouldn't sell the public short on needing an overly simple scale to indicate the level of threat. Short answer: Don't eliminate the surge indications. It's a really bad idea.

[Lea G]

How can it be put any more clearly than you already did, Tim. Very well said and I agree with your following words completely. My husband and I wondered at the time why Ike wasn't categorized a Cat 4 or 5 based on its surge threat alone. We live in Seabrook and the winds did not concern us nearly as much as the storm surge did.

***
I think this is a big mistake. The Saffir-Simpson Scale works. Leave the scale alone but rank storms based on wind speed OR storm surge, whichever is the greater threat.

For example, in Hurricane Ike we had 100 mph winds but a 15-20' storm surge. In this case, surge trumps wind, therefore it would have been ranked a category four storm. Not one person would have stayed on Bolivar Peninsula if they had heard a massive category four hurricane was going to make a direct hit.

[Jon Peterson]

Tim:

They should not remove items. What should be added is the reporting of the lowest barometer readings. Also, The computer models used should be tweaked so you can rely on them better.

Storms are like a two-ton bowling ball. It goes pretty much where it wants. We need all the info we can get.

[Ramona]

I agree - LEAVE the Scale just as it is. My dad has used the info in the scale to tell which direction we need to go when leaving for a hurricane since it was developed. The elderly people know how to read this scale and have passed this knowledge to their children. If you are from the costal states, you know how to use the information on SSScale. "If is isn't broken don't fix it", add to it if you must, but leave it alone! This is mother nature you are trying to figure out - she will change her mind often, man will never be able to control her, we need to respect the weather. Changing the scale will not make the hurricanes any less dangerous, it will just cause more problems for all of us.

[Natalie]

I say we should go with your idea of whichever one is stronger, that's what it should be! It does seem to make the most since so that people do not underestimate the storm.

[Shreela]

"...[B]ut rank storms based on wind speed OR storm surge, whichever is the greater threat."

No, no, no! Give us both! People far away from the threat of surge still need the wind-threat reports, don't you think?!

But really, why completely drop surge from SS# system, only to 'talk' about "creating a second scale just for storm surge" Separate them, but provide both. Why make something so simple into such a complicated debate? Is there $$$ involved?

[Robert]

Yes I like the idea of using whichever number is more severe (surge or windspeed) to determine the threat.

Or as a second option announce the surge seperate. No matter what... the current scale and windspeeds should not be changed !

[John]

I agree mostly with everything you said but why make it either or? Why not just calculate both into the same scale. I wouldn't want to completely ignore wind speed just because it is the weaker force.

[nsj]

Good points, and I love the debate.

Philosophically, anything we do that reduces hurricanes -- or how we categorize their potential impacts -- down to one threat or another is suspect. Hurricanes are multi-faceted events and they have many different impacts, not all of which are adequately captured in wind speeds.

Unfortunately, I'm not sure our ability to quantify storm surge makes it a good choice as a categorization tool. For example, the same storm may have a much more significant storm surge impact on a shallow coastline than on a deeper one. Plus, we can measure wind speeds with reasonable accuracy, even over open water -- assessing the true impact of storm surge is more difficult.

Perhaps there's room to adapt the integrated kinetic energy scale and map those values to the Saffir-Simpson category numbers and description?

In any event, great thought!

[Kristin]

I agree with you 100%! I also agree that taking out the SSS would be a horrible mistake.

[Jason D]

I'm not a meteorologist, but I do enjoy weather. I don't think there is a 'good' way to get ALL of the necessary information into ONE scale and have it reasonably simple. The only way to do this is to have multiple scales, or subscales or something of the sort, like a 1A, B, or C for storm surge categories and/or wind speed. Either way, its going to get complicated. I think people would get used to it and there would be an easy conversion to get the old storms to the new scale. With that said, your suggestion of basing it on storm surge OR wind speed is not a bad one. I do not think tossing the whole scale is a good idea, that is for sure. It may need some adding to, or adjusting, but it is a solid base I think. Your suggestion, however, might lead to problems with comparing new storms and old storms using the same scale with a different variable. It might be a record keeping problem.

RESPONSE from TIM HELLER: We would need to go back and reanalyze previous storms to check and see if the surge was worse than the wind at landfall. That type of thing has been done before. In 2002, another look at the wind data from Hurricane Andrew prompted the NHC to raise it to a category five at landfall.

[Kyle]

This sounds like an awful idea. The point you make for Ike alone shows how bad of a mistake this is. I agree completely that whatever is a greater threat should rank the storm, not just wind.

Take the Enhanced Fujita Tornado Scale, it measures the overall damage the tornado would cause. It should be the same for hurricanes. Taking the storm surge out of the equation completely ignores the "overall damage" factor.

[BR Jones, N5EVD]

Please keep the base Saffir-Simpson Scale but revise storm surge data if needed and base it on the "above sea level". The Saffir-Simpson Scale is needed for historic perspective and now is NOT the time for a entirely new hurricane effects scale.

BR Jones, N5EVD

[Zachary Bullard]

Keep it...Just winds could harm millions of people! Your making a huge mistake!!!!!

Zachary
Weather Site Owner
In weather for 4 years

[Carolina]

I completely agree with you. There are so many different threats from hurricanes, and no two storms are alike - be it heavy rainfall, wind speed, storm surge, tornado threat, etc etc etc. It's silly to do away with one part of a system that works fine; just amend it to let people know what the greatest threat will be from each storm.