Proposing A New Scale To Cover All Bases

[brunota2003]

I know we've had discussions about this before, and I'm pretty sure I've posted some of my ideas in those threads...but it is 5 am on a Monday and I am feeling rather lazy

So, I was digging through some of my old ideas for revising the current scale, and including markers for rain, waves, surge, and flooding...as well as wind. I think, overall, a scale like that would provide a better overall "threat" level than the current SS scale does. I created a 6 point and a 10 point scale a couple years ago, but decided to modify the 6 point scale (I like that one best, it is closer to today's scale). I used increments of 0.5 on the original 6.0 scale, but felt it would be better off with just the 1 to 6...and I edited the numbers so that it would be a little easier to "max" out each respective category (except flooding, that one stayed the same).

Here are the different criteria:

Wind:

0.5 <39
1.0 40 - 55
2.0 55 - 75
3.0 75 - 100
4.0 100 - 130
5.0 130 - 160
6.0 160+

Surge:

1.0 0 - 3 feet
2.0 3 - 6 feet
3.0 6 - 12 feet
4.0 12 - 18 feet
5.0 18 - 25 feet
6.0 25+ feet

Waves:

1.0 0 - 5 feet
2.0 5 - 10
3.0 10 - 20
4.0 20 - 30
5.0 30 - 40
6.0 40+ feet

Rainfall:

1.0 0.0 - 3.0 inches
2.0 3.0 - 6.0 inches
3.0 6.0 - 9.0
4.0 9.0 - 12.0
5.0 12.0 - 15.0
6.0 15.0+ inches

Inland Flooding:

1.0 Low: Nuisance flooding, small streams flooding, poor drainage areas and street flooding may occur.
2.5 Medium: Smaller rivers may flood, nuisance flooding likely. Some evacuations possible.
4.0 High: Major flooding possible, many evacuations likely due to flooding.
6.0 Extremely High: Flooding of epic proportions likely (record levels).

To get the overall threat number, you take the 5 individual numbers and add them up, then divide by 5.


Here are a few examples:

Hurricane Isabel:
September 17 5 pm EDT advisory
Winds: 105 mph (4)
Surge: 7 to 11 feet (3)
Waves: 25 feet (4)*
Rainfall: 6 to 10 inches (3)
Inland Flooding: Medium (2.5)

Overall threat assessment:
On a scale of 1 to 6: 3.3

*No wave size is in the TCR or reviews by NWS Newport/Morehead City, so wave size is a guess.

Hurricane Katrina:
August 28 5 pm EDT advisory
Winds: 165 mph (6)
Surge: 18 to 22 feet, locally as high as 28 feet (5)
Waves: 40 feet (6)*
Rainfall: 5 to 10 inches with higher amounts possible (4)
Inland Flooding: Medium (2.5)

Overall threat assessment:
On a scale of 1 to 6: 4.7

*Significant Wave size out in the Gulf, per a NOAA buoy, measured between 30 and 55 feet, according to the TCR.

Hurricane Issac:
August 28 5 pm EDT advisory
Winds: 80 mph (3)
Surge: Max 6 to 12 feet (3)
Waves: 20 feet (4)*
Rainfall: 7 to 14 inches, up to 20 inches possible (5)
Inland Flooding: High (4)

Overall threat assessment:
On a scale of 1 to 6: 3.8

*No wave size is listed in the advisories, and post storm studies are incomplete at this time (this was done in 2012).

Tropical Storm Ernesto:
Winds: 70 mph (3)*
Surge: 3 to 5 feet (2)
Waves: 15 feet (3)**
Rainfall: 4 to 8 inches, up to 12 inches (3)
Inland Flooding: Medium (2.5)***

Overall threat assessment:
On a scale of 1 to 6: 2.7

*Increased wind threat to 3 due to possibility of slight strengthening prior to landfall.
**No wave data, 15 feet is an estimate.
***Life threatening flash floods listed as possible, no mention of major river flooding though. Decided Medium threat was appropriate.

Hurricane Ike:
Winds: 105 mph (4)
Surge: Up to 20 feet, 25 feet possible (5)
Waves: 25 feet (4)*
Rainfall: 5 to 10 inches, 15 possible (4)
Inland Flooding: Medium (2.5)

Overall threat assessment:
On a scale of 1 to 6: 3.9

*Estimate.

Note:
Please take the wave height estimates with a grain of salt. I did try to do some research into them, but most of them are just "guesses" to fill the slot in. For storms away from land, use just wind speed and maybe wave heights, since that is the only data that would be available.

So on this 1 to 6 scale, in order from weakest to strongest, you would have:
Tropical Storm Ernesto: 2.7
Hurricane Isabel: 3.3
Hurricane Issac: 3.8
Hurricane Ike: 3.9
Hurricane Katrina: 4.7

On an interesting note, notice that on this scale, Category 1 Hurricane Issac is actually considered "stronger" overall than Hurricane Isabel, despite Isabel being a Category 2 officially. No scale will ever perfectly capture the full effects of a hurricane, especially for any one given spot...but isn't it about time we devise a way to grade them appropriately and account for all of their hazards, not just wind?

[Alyono]

the problem is Isaac rated higher than Isabel, despite Isabel being far more destructive than Isaac

[Hurricane_Luis]

Another thing is that The amount of rain is different in different parts of the tropical cyclone, also lots of people what different things and sometimes its politics. Bottom line is there are lots of problems with a adopting a new universal scale which is why no one has bothered to change them.

[BigB0882]

And isn't rainfall rate and inland flooding a little redundant? A higher rainfall rate will lead to a higher inland flooding threat. It weights that aspect very heavily since those 2 will almost always be aligned.

[Hammy]

I personally think the current scale is fine, it would be too complicated and confusing for people adopting a universal scale like this, not to mention the potential for the media to blow it out of proportion even further. It would be a good idea though, specifically for landfalling systems, to adopt a second scale specifically for surge.

[RL3AO]

I personally think the current scale is fine, it would be too complicated and confusing for people adopting a universal scale like this, not to mention the potential for the media to blow it out of proportion even further. It would be a good idea though, specifically for landfalling systems, to adopt a second scale specifically for surge.

Hopefully the specific surge warning will help, although clearly that will only impact US systems. Relaying the threat of surge and flooding is one of the most important topics in hurricane forecasting IMO.

[cigtyme]

My issue is for a storm like Isaac, in 2012. I live in Houma, La. That storm was at 70 MPH for eternity. It hit 75 and it was like the end of the world. It made me think that no one was doing anything at 70, but starting panicking at 75MPH. There is little difference between 70 and 75 mph storm. People tend to freak out when TS turns to Hurricane, but disregard the TS. I think labeling them needs revamping in this regard. Like 35 to 55 just a TS, then 56 to 70 severe TS, for example!