Do We Need a Category 6 for Hurricanes?

[Randy Zipser]

Don’t the NHC surge maps encompass these factors, via the color scale of surge inundation?

They might, in broad, general terms. But the idea behind creating a new WRAS is to assign a specific scale number to the anticipated landfall location and surrounding coastal region, similar to the SSHWS for wind risk (Category 1-5). Coastal residents might respond with more evacuation urgency to numbers than just to "broad-brush" color-scale schemes on maps.

Admittedly, the downside to having both wind- and water-risk scales is that both wind and water start with the letter "W," so the messaging might cause confusion with the public (at least at first). One way to resolve that messaging problem, however, would be to have a "W/S" [Wind/Surge] scale designation. For example, instead of Category 4, public hurricane warnings would say "W4/S3" [or "Wind 4/Surge 3"] where both scales have 5 levels of severity (because the public is already used to a 5-level scale). So, there may be no need for a Category 6 after all...

 

[Randy Zipser]

Lastly, the direction (onshore vs. offshore) of winds relative to the coastline due to the direction of approach of the tropical cyclone would have a huge impact on the storm-surge potential.

...to have a "W/S" [Wind/Surge] scale...

It would be possible to have a W5/S1 event, which makes a huge difference as to how the potentially-affected residents would prepare/respond in terms of evacuation.

 

[WallsC]

They might, in broad, general terms. But the idea behind creating a new WRAS is to assign a specific scale number to the anticipated landfall location and surrounding coastal region, similar to the SSHWS for wind risk (Category 1-5). Coastal residents might respond with more evacuation urgency to numbers than just to "broad-brush" color-scale schemes on maps.

Admittedly, the downside to having both wind- and water-risk scales is that both wind and water start with the letter "W," so the messaging might cause confusion with the public (at least at first). One way to resolve that messaging problem, however, would be to have a "W/S" [Wind/Surge] scale designation. For example, instead of Category 4, public hurricane warnings would say "W4/S3" [or "Wind 4/Surge 3"] where both scales have 5 levels of severity (because the public is already used to a 5-level scale). So, there may be no need for a Category 6 after all...

The question probably becomes one of public utility, both with relation to your point specifically, and with regard to the question of this thread about the need for a "category 6."

The Saffir Simpson scale is basically the other side of the coin of the Enhanced Fujita scale we use for tornadoes. We have chosen for practical purposes to define a tornado's wind speed retrospectively by assessing the damage it did, and the SS scale attempts to predict damage based on wind speed. As you note, it is imperfect as a warning metric because it fails to account for the biggest killer in hurricanes - surge. Fortunately, raw wind speed does tend to correlate well with surge, although diameter of the wind field is probably more important from a scientific perspective.

Although more precise, the general public may not digest a dual-rating system as well as we might hope. It is easy to picture someone who doesn't even know what the W and S stand for saying, "Who cares if it's an S4, it's only a W2, I'm fine," and then try to ride it out in their beach house.

A cat 6 rating isn't needed because practically speaking, the damage would be similar. We could probably argue that an EF6 tornado category could be created, but why bother when an EF5 will already strip your house to its foundation just as effectively? It would also be unwise to dilute the scale. Will people take a cat 3 or 4 less seriously if they know it's on a scale of 6?

Scientifically, the min pressure and storm diameter are much more important to assessing ACE and true power of a storm than max wind speed ever will be. The SS scale is primarily a tool for disseminating information to the public in a way that is both concise and actionable.

 

[Randy Zipser]

Scientifically, the min pressure and storm diameter are much more important to assessing ACE and true power of a storm than max wind speed ever will be.

Very true and point well taken. That level of technical "scientific" detail will only likely confuse the public, however. How many people in the non-meteorological community even know what normal sea-level pressure is in millibars, let alone in the inner core of a small-diameter Category 5 hurricane or typhoon (in either millibars or inches of mercury)? And what about the relationship between minimum "eye" diameter and maximum eye-wall wind speed? Such concepts will go right "over the head" of the vast majority of the lay public. As you point out, the simpler SS scale is probably just the right amount of detail that the public needs to know to act upon for safety.

 

[Boris Konon]

This proposal I find most interesting, and has merit.

Surface Pressure a More Skillful Predictor of Normalized Hurricane Damage than Maximum Sustained Wind

https://journals.ametsoc.org/view/journals/bams/101/6/bamsD190062.xml

Continuing the discussion...
The Saffir-Simpson scale is outdated IMHO. This was already shown after 2005 when pressure and storm surge were removed from the table (Katrina was the catalyst - 920 mb pressure at landfall, but "only" 110 kt winds, yet the surge was the highest ever recorded in the U.S. (18 ft or more was Cat 5, and Katrina's surge was 28 ft)!

This obsession w/ wind is often misplaced. Of the 3 main risks in a hurricane, wind is the *least* of the risk overall. And wind becomes moot once well inland as the TC decays, but the freshwater flooding risk often *increases*.

And using category 1-5 misleads the public and officials as to overall risk. Sandy was only a category 1, but resulted in a record storm surge in NJ and NYC, equivalent to what you;d typically see in a category 3.

Keeping it simple in this case I think does more harm than good now.

We should change the scale to an *impact* scale, as that is what really matters in the end to the public. The WSSI (Winter Storm Severity Index) does this well.

Winter Storm Severity Index (WSSI)

Winter Storm Severity Index Web Display

WSSI plots get very specific, accounting for things like elevation.

Not all hurricanes are the same for impact. For instance, does the hurricane hit at low or high tide? It is moving fast or slow? How large is the RMW and radii of gale-force winds? Is there baroclinic interaction or not? Using just wind for designated categories oversimplifies the situation.

And all this would line up w/ what the NWS has become more over time - Impact-Based Decision Support Services (IDSS).

In the idea that we keep the current category scale...
As for any additional catagories, I think I had mentioned before, would one prepare *any* different from a Cat 5 or 6? The answer is NO! Once you get to 160 mph, the damage is complete and the risk extreme, so adding any more is like pouring water into an already full bucket.

I suspect this category notion is pushed to further the climate change agenda ("look, we had to *add* category to hurricanes b/c of climate change!"). Also, it is merely a tool for the media to hype more. In addition, we as a society are *obsessed* w/ labeling things into nice, neat packages/categories, but that can only be taken so far, and more is not always better. Wx phenomena typically exists on spectrum, not into solid categories. It's like the three types of supercells, LP, CL, and HP., but how often do odd hybrids and combination exist?

Having just 1-5 is a psychologically satisfying range. Ending in brackets of 0 or 5 is a good thing in communications and messaging. Sounds more official. There is reason why we see top 10, 25, 50, or 100 for lists everywhere!

 

[WallsC]

This obsession w/ wind is often misplaced. Of the 3 main risks in a hurricane, wind is the *least* of the risk overall.

I definitely agree with this. All it takes is a quick look at the list of most costly US hurricanes of all time. The top two are so far ahead of #3 it's scary - and neither one of them was a cat 5 at landfall. It was the surge/flood/water impact that led to their absolute armageddon-level catastrophic impacts.

In some morbid way, wind speed is way sexier than other metrics. It is also far easier to quantify and predict in advance. That is probably why it continues to be the fall back as the core metric emphasized to the public.

Unfortunately, it is unrealistic to expect the general public to be able to confidently interpret anything beyond a simple 1-5 scale. The best way forward might be to modify or replace SS with something that takes expected water impact into account "behind the scenes," and continue to distill this out as a 1-5 scale for the public.

Alternately, change the warning system entirely. Take the emphasis off of the storm itself, and target the warnings as expected impacts to different areas. There has already been a move this direction with surge warnings and extreme wind warnings, but these products often get released late in the game. Additional products like "severe landslide warning" for mountainous areas could be useful if released far enough in advance. Unfortunately, such warnings would pose significant forecasting challenges to get them in front of the public in a time that would allow for a meaningful response without excessive false alarms.

 

[Randy Zipser]

More about the discussion that never seems to go away...BTW, as I write this, it's a shivering 29 degrees in my area of Central Florida...

My local newspaper, the Tampa Bay Times, published a good, thought-provoking op-ed yesterday (11/11/2025) about having a "Category 6" in the aftermath of Hurricane Melissa, by far, the most intense hurricane in the relatively "quiet" Atlantic Basin in 2025. Please read the link below:

Is it time for a ‘Category 6′ hurricane designation? | Column

 

[Boris Konon]

More about the discussion that never seems to go away...BTW, as I write this, it's a shivering 29 degrees in my area of Central Florida...

My local newspaper, the Tampa Bay Times, published a good, thought-provoking op-ed yesterday (11/11/2025) about having a "Category 6" in the aftermath of Hurricane Melissa, by far, the most intense hurricane in the relatively "quiet" Atlantic Basin in 2025. Please read the link below:

Is it time for a ‘Category 6′ hurricane designation? | Column

Randy, thank you for posting. Looking at Melissa and the 2025 Atlantic season as a whole, it allows me to further talk
about things and present some information one may not be aware of.

The article states:
"Melissa’s sustained winds reached 185 mph at landfall in Jamaica. Historical records show that only a
handful of Atlantic hurricanes have reached such speeds at landfall. Melissa’s 185 mph ties it with
Hurricane Dorian (2019), Hurricane Wilma (2005), Hurricane Gilbert (1988) and the 1935 Labor Day
hurricane."

Not totally correct. Wilma and Gilbert *peaked* at 185 mph over the open ocean (likely too low given what we
know now), but were *not* 185 mph at landfall. Goes to show how things are often incorrect, esp. w/ the details,
in articles these days. And in science, the details count! In this case, how strong a hurricane is at landfall frequently
makes *huge* difference as to total impact.

The article also states:
"As we continue to assess the toll left by Hurricane Melissa, one thing is clear: what we know so far confirms a
scientific trend that has been years in the making. The ocean’s surface temperature is rising and the extra heat is
fueling hurricanes, making them more powerful and lethal."

Starting an article w/ a contested issue is not the way to do it. You immediately create conflict/divide and turn some
readers off by "poisoning the well" w/ such a pretext. And the line, "as we continue to assess the toll..." What does
that have to do w/ the title of the article really? Any strong hurricane that makes landfall leaves a toll to assess. It is a
non-sequitur statement and superfluous. As if the reader does not know a hurricane leaves a toll?

Every time we get a strong Cat 5, this same, "do we need a Category 6?" line comes up in the MSM. Same recycled
story trope that waits in the journalism canned queue. How about try something original or more-thought provoking than
"re-heated leftovers" posted merely for content?


Talking about the warmer ocean temps and hurricanes in a broad sense...
When I said "contested issue" above, I need to elaborate. Yes, in a vacuum by itself, warmer ocean temps do make
hurricanes stronger, but this is cherry-picking logical fallacy or the fallacy of incomplete evidence.

There are many other factors out there that modulate hurricane intensity, and starting from the very basics, and I have
said this before, all the warmer ocean in the world is meaningless if the atmosphere does not cooperate, and this is
proven easily. SSTs across most of the tropics globally are more than enough to support intense hurricanes year-round,
but they do not happen. Not only that, most disturbances never become TCs, even during the peak of the season in each
ocean basin. This is b/c atmospheric conditions on a large-scale have to be conducive, esp. in terms of wind shear and
moisture, among other things, otherwise, no dice.

And the 2025 Atlantic hurricane season has shown an example of this. 3 of the 4 intense hurricanes all struggled for days
as lower-end TCs before becoming intense (Erin, Gabrielle, and Melissa). T his was due to unfavorable atmospheric conditions
in the deep tropics. And Erin, Gabrielle, and Humberto had to wait until they got out of deep tropics before becoming intense, further showing how the deep tropics were not favorable overall much of the season.

Some have noted of the 5 hurricanes this season, 4 become Cat 4+, and thus a larger percentage of hurricane-strength TCs
are more intense, and this cherry-picking narrative get inserted for trends in recent decades. But this is deception by math, in
this case, using only percentages. The omitted fact is that there are less total hurricane-strength TCs overall. So *of course*
the percentage of intense will be higher! It does not necessarily mean there are more intense in absolute numbers.

One thing of note is that we lacked long-tracked, classic Cabo Verde hurricanes this season, and the reason is given above.
What we have been starting to see, and noted in climate studies, is the yes, hurricanes that form have a more likelihood of becoming intense, but the number of hurricanes and their durations as intense hurricanes, is coming *down*. This has been
noted most in the last 30 years in the South Indian Ocean basin (second most active tropical basin in the world by annual ACE).
But these kind of studies do not get headlines. You'd be surprised how much literature and studies areout there on the climate
issue that don't see the light of day, and empirical observations over time validate a lot of this work.

So why are we seeing TCs struggle more/not as intense as long? It goes back to large-scale patterns and features across the
tropics as temps warm. For instance, changes in the Hadley Cell, the Walker Circulation, phases of the MJO, Convectively-
Coupled Kelvin Waves (CCKWs), the African Easterly Jet (AEJ), and so on. These impact more local things like the mean
position of the ITCZ, Sahel rainfall, Saharan dust outbreaks, the frequency and distribution of TUTTs, etc. These phenomena
are very complex and interact in ways outside of warming that we still do not fully understand, but clearly are major factor
in TC frequency and intensity. How come these factors, which in many cases do the opposite of the mainstream narrative that hurricanes get worse across the board in a warming globe, never get mentioned much of at all? Well, it's b/c it doesn't fit the current narrative, and also likely b/c from a public view, many know the connection to SSTs and hurricanes in a basic sense (they need warm ocean to form and get intense), so this an easy, linear platform for politicians and global elite to sell to the masses
to push a CAGW narrative. Glossing over a complex system is bad science.

So hurricanes get stronger in a warmer globe is valid, but at the same time, the number of hurricane-strength TC totals tend to
go down and their duration as being intense also goes down. Is that not a somewhat balanced, some loss/some gain scenario? Of course, it's not an exact 50-50 balance, but it shows that things are not as bleak/bad as they are portrayed. Yet this part of left out of the narrative. It is always worse across the board for warming temps, which remarkablely vapid and arrogant considering how complex the Earth's system is and thumbs its nose at the Earth's ability remaining stable for life to flourish for 100s of millions of years despite going through far worse climate swings and catastrophes (asteroid impacts, supervolcano eruptions, ice ages, etc.).

 

[Boris Konon]

More about the discussion that never seems to go away...BTW, as I write this, it's a shivering 29 degrees in my area of Central Florida...

My local newspaper, the Tampa Bay Times, published a good, thought-provoking op-ed yesterday (11/11/2025) about having a "Category 6" in the aftermath of Hurricane Melissa, by far, the most intense hurricane in the relatively "quiet" Atlantic Basin in 2025. Please read the link below:

Is it time for a ‘Category 6′ hurricane designation? | Column

One other item that concerning SSTs. It is lot more than about absolute ocean temp for TCs. What goes on below the surface
of the ocean plays a signficant role -- ocean stratification. Water masses w/ different properties, such as salinity (halocline), oxygenation (chemocline), density (pycnocline), and temp (thermocline), form layers that act as barriers to water mixing -- this barrier prevents water from passively mixing across the boundaries. This in itself plays a role in modulating TC intensities, and it varies geologically across the globe, so each TC basin can not be treated the same when it comes to impacts of warming.

Here is a recent paper that talks about this:

Why Do Eastern North Pacific Hurricanes Intensify More and Faster than Their Western-Counterpart Typhoons with Less Ocean Energy?

https://journals.ametsoc.org/view/journals/bams/103/11/BAMS-D-21-0131.1.xml

There is a lot more out there than just what you hear in the MSM or within circles in any given field or discipline.
One should strive to expose and inform oneself well beyond echo chambers or any particular "side."

 

[William Monfredo]

News can appear fun & entertaining; I'm glad for everyone that enjoys it.
Yet, I do not want to be a product shaped by a homogenized line of thinking.
I've found so much of the weather "news" simplistic, naive, & questionable.

A couple examples of weather that didn't get emphasized:
When NHC thought TS Jerry would become a hurricane this year and didn't, it earned the monicker Disheveled Jerry from them before it died.
And when hurricane Lili rapidly de-intensified from a Cat 4 to Cat 1 years ago, no one said, "Do we need a Category 1/2 ?"

The Rapid Intensification and Subsequent Rapid Weakening of Hurricane Lili as Compared with Historical Hurricanes

Abstract The purpose of this paper is to compare the rapid intensification and rapid decay of Hurricane Lili with historical records to determine whether similar events have occurred in the past. Data for this study were compiled from the historical hurricane database that consists of all...

journals.ametsoc.org

 

[Boris Konon]

Lili from Oct 2002 was a case where it appeared it clearly benefited from passing over the warm Loop Current in the Gulf and lost it
after moving away from it. There was no apparent strong baroclinic interaction or wind shear/dry air to otherwise promote such rapid weakening.

Lili went from 125 kt peak offshore to 80 kt at landfall in 13 hr. That is huge for sensible wx impact.

Also, Milton from 2024, weakened 40 kt (pressure up 58 mb) in 16 hr leading up to landfall. It is listed at 100 kt at landfall, but I think that is a bit too high. The highly sheared nature and rapid decay on satellite does not support such winds. Yes, 958 mb can support 100 kt winds, but that wind-pressure relationship is for more symmetric hurricanes w/ a solid inner core.

I'd like to see more studies why the above happens. The door swings both ways here. Just b/c rapid intensification gets all the headlines and fits a narrative does not mean other aspects just as important or should be ignored!

And Lili rapid weakening was not forecast, but Milton's was very well w/ the new HAFS model. The HAFS IMHO represents a big leap for TC intensity forecasting.

 

[Randy Zipser]

One should strive to expose and inform oneself well beyond echo chambers or any particular "side."

Excellent, thorough, impartial information you have given and greatly appreciated, Boris!

In starting (and recently continuing) this thread, my aim was to stimulate discussion based upon contributions from several different sources, where at least reasonably vetted or credible. I'm not necessarily saying that I agree with any particular (or all) viewpoints expressed, which is why I used such adjectives as "thought-provoking" in describing articles linked herein. I'm just the "messenger" in the overall context; but more importantly, I have no desire whatsoever to promote any specific agenda--quite to the contrary, in my view, the purpose here is to have totally open, unfettered, and impartial discourse!

I agree with and appreciate your exposing or "calling out" the above "weakness" in information disseminated through many print and online media sources, including the ones posted in this thread.

I also acknowledge that you are vastly more knowledgeable than I am about this (and many other) topics that we are discussing on the website, which is why I (and likely all other ST readers) so much enjoy reading and learning from your detailed commentaries. Your replies and discussions are exactly the kind of commentary that make ST the very best website of its kind on the internet: better, more intelligent, and more informative than any social media outlet, IMHO!!

Please keep up the great discussion(s), Boris...I really enjoy hearing from you! RZ

I've found so much of the weather "news" simplistic, naive, & questionable.

I absolutely agree, William. But also remember that "general weather/climate news" for the public is designed not to be of the level of detail that Boris or you, for example, might publish here. The omission of "certain facts, or perhaps, more-complex details" is not always so much part of an intentional agenda to steer the readers toward a particular result or conclusion as one of publisher practicality, e.g., publishing deadlines, having only so much column space to allot to the story, etc. Keep it short and simple...the exact opposite of what you'd find in Monthly Weather Review.

 

[Jeff Duda]

I really appreciate the quality of this discussion, everyone! I also appreciate how you were all able to minimize the underlying politics in topic such as this. This thread really increases the quality of discussion on this forum.

 

[Warren Faidley]

I wonder if the progress of modern technologies to accurately measure wind speed, rainfall and pressure are changing statistics, much like hundreds of chasers and modern radar are adding to tornado counts?

 

[Jeff Duda]

I wonder if the progress of modern technologies to accurately measure wind speed, rainfall and pressure are changing statistics, much like hundreds of chasers and modern radar are adding to tornado counts?

Probably not to any point of statistical significance. The more likely improvements are coming from more spatially dense observations and more stable measurement systems (i.e., those more robust to being destroyed by extreme weather).

Now...could more dense wind speed measurements result in increases in maximum wind speeds in landfalling TCs? Sure, but that doesn't mean some past in-situ observations still haven't captured wind speeds that are close to the actual maximum found in events. I don't think that justifies expanding the SSHWS.