Saffir-Simpson Hurricane Scale now "Hurricane Wind Scale"

[Chacor]

http://www.nhc.noaa.gov/aboutsshs.shtml

The Saffir-Simpson Hurricane Wind Scale is a 1 to 5 categorization based on the hurricane's intensity at the indicated time. The scale provides examples of the type of damages and impacts in the United States associated with winds of the indicated intensity. In general, damages rise by about a factor of four for every category increase. The maximum sustained surface wind speed (peak 1-minute wind at 10 m [33 ft]) is the determining factor in the scale. The historical examples (one for the U.S. Gulf Coast and one for the U.S. Atlantic Coast) provided in each of the categories correspond with the intensity of the hurricane at the time of landfall in the location experiencing the strongest winds, which does not necessarily correspond with the peak intensity reached by the system during its lifetime. The scale does not address the potential for such other hurricane-related impacts, as storm surge, rainfall-induced floods, and tornadoes. These wind-caused impacts are to apply to the worst winds reaching the coast and the damage would be less elsewhere. It should also be noted that the general wind-caused damage descriptions are to some degree dependent upon the local building codes in effect and how well and how long they have been enforced. For example, recently enacted building codes in Florida, North Carolina and South Carolina are likely to somewhat reduce the damage to newer structures from that described below. However, for a long time to come, the majority of the building stock in existence on the coast will not have been built to higher code. Hurricane wind damage is also dependent upon such other factors as duration of high winds, change of wind direction, amount of accompanying rainfall, and age of structures.

Earlier versions of this scale - known as the Saffir-Simpson Hurricane Scale - incorporated central pressure and storm surge as components of the categories. The central pressure was utilized during the 1970s and 1980s as a proxy for the winds as accurate wind speed intensity measurements from aircraft reconnaissance were not routinely available for hurricanes until 1990. Storm surge was also quantified by category in the earliest published versions of the scale dating back to 1972. However, hurricane size (extent of hurricane force winds), local bathymetry (depth of near-shore waters), and topographic forcing can also be important in forecasting storm surge. Moreover, other aspects of hurricanes - such as the system's forward speed and angle to the coast - also impact the storm surge that is produced. For example, the very large Hurricane Ike (with hurricane force winds extending as much as 125 mi from the center) in 2008 made landfall in Texas as a Category 2 hurricane and had peak storm surge values of 15-20 ft. In contrast, tiny Hurricane Charley (with hurricane force winds extending at most 25 mi from the center) struck Florida in 2004 as a Category 4 hurricane and produced a peak storm surge of only 6-7 ft. These storm surge values were substantially outside of the ranges suggested in the original scale. Thus to help reduce public confusion about the impacts associated with the various hurricane categories as well as to provide a more scientifically defensible scale, the storm surge ranges, flooding impact and central pressure statements are being removed from the scale and only peak winds are employed in this revised version - the Saffir-Simpson Hurricane Wind Scale.

[artist]

so will they then make a statement regarding the other issues? Interesting chacor, thanks for posting.

[RL3AO]

I propose the Saffir-Simpson One-Minute Sustained Wind Speed Tropical Cyclone Scale (SSOMSWSTCS). It rolls off the tongue.

[artist]

I propose the Saffir-Simpson One-Minute Sustained Wind Speed Tropical Cyclone Scale (SSOMSWSTCS). It rolls off the tongue.

[cpdaman]

why don't we just have a scale for winds AND for Surge

so for example IKE could be taken more seriously by people living near the water ....since surge is a big killer

so using ike as an example the media could say strong cat 2 heads for texas coast....with CATEGORY 4 (guessing) storm surge

So still concentrate on the winds for the scale (to not confuse the public too much) but be sure to add that it has a surge of a certain category cane......they will get the basic message.....(i.e that it will be "bad")

[Tampa Bay Hurricane]

IMO this is much better than the old scale.

[Sanibel]

They announced that on CNN that the SS scale was now wind only and surge would be determined on a storm by storm basis.

2008 was weird in the Gulf. Storms that would normally (I know, Izzy etc) have rebounded better struggled to get their cores back together.

[southerngale]

This is great... much better than the old scale. Hopefully, more people will pay attention to the surge warnings, but unfortunately, many people will still remain uninformed.

[tolakram]

People will still rate the danger on the number, I don't see any improvement. Awe it's just a 2, turn off the tv.

[RL3AO]

Its a psychological change. I don't know if it will do much. Ike would still be "just a 2".

[srainhoutx]

Its a psychological change. I don't know if it will do much. Ike would still be "just a 2".

I believe many will rethink the process in time. Many of those that thought "Ike is just a 2" will certainly look at things a bit differently.

[wxman57]

why don't we just have a scale for winds AND for Surge?

so for example IKE could be taken more seriously by people living near the water ....since surge is a big killer

so using ike as an example the media could say strong cat 2 heads for texas coast....with CATEGORY 4 (guessing) storm surge

So still concentrate on the winds for the scale (to not confuse the public too much) but be sure to add that it has a surge of a certain category cane......they will get the basic message.....(i.e that it will be "bad")

There's no such thing as a "Category 4 surge", is one problem. Surge is not so much a factor of Saffir-Simpson classification - that's the main problem they're addressing. A Cat 1 hurricane could produce a surge anywhere from a few feet to over 20 feet, depending upon a number of variables:

1. Size of the wind field (RMW and extend of hurricane-force winds)
2. Where the hurricane hits (coastal shoaling factor that varies with water depth offshore). Also, bays enhance surge
3. Speed of movement
4. Angle of approach to coast

Let's say you have a hurricane in the south-central Gulf moving NW. This hurricane striking south Texas might produce a 6-10 foot surge. But if the forecast is wrong and it strikes southeast Louisiana, then the surge could be 25 feet there and along the MS coast. So, somewhere between 6 and 25 feet for surge. Same hurricane, just different landfall point. How do you quantify that with a number? You certainly can't relate it to the SS wind scale.

Wind is independent of all these variables, so a scale works OK to describe potential wind damage type - but SSHS doesn't do a good job of describing the extent of wind damage.

This brings up an issue with the proposed NHC surge warnings that they proposed last winter. I talked to Bill Read and Jack Bevin about the warnings when I was attending the IHC and NHC. The NHC put off implementation of surge warnings until 2012 at the earliest. Question is - what constitutes surge warning criteria? A water level increase of 2-3 feet in some areas could cut off evacuation routes. In other areas, it's just an abnormally high tide that doesn't affect anyone. So surge criteria would be different all along the coast. They're trying to figure out how they can use standard warning criteria when surge impact varies greatly from one place to another.

[stormcloud]

As for Ike, Galveston and the Bolivar Peninsula were warned that a catastrophic and life threatening storm surge was on the way. Many dismissed the warnings as being either incorrect or "it's not going to happen here" thoughts.

[wxman57]

As for Ike, Galveston and the Bolivar Peninsula were warned that a catastrophic and life threatening storm surge was on the way. Many dismissed the warnings as being either incorrect or "it's not going to happen here" thoughts.

That is true. I know that on Wednesday, September 10th, we were talking about a potential 20-25 foot surge into Galveston Bay with landfall between Galveston and Matagorda. I think the biggest problem was the failure of Galveston's Mayor to take the storm seriously. I was yelling at the TV each time she came on, downplaying the threat. She may have cost some residents their lives. Can't believe she hasn't resigned.

[MGC]

Yep, I remember watching her pretty much down play Ike and was thinking "did't they learn anything from Katrina?" I still think people will attach a surge value to a particular SS scale. The SS scale has been in use over a generation and has been ingrained into the minds of coastal residence.....MGC

[cpdaman]

WXMAN57 i understand your point......I beleive the public MAY pay more attention to saying we have a "CAT 4 surge" just because they are familiar with the fact that cat 4= real bad.

And to use your example the forecast could say we are expecting a hurricane with x caterogy winds and should it hed up to LA/MS it will have cat 4 surge and if it bends west it will have cat 2 surge due to the area being less prone to surge......i dunno ......people smarter than me are working on it....i'd like to think

but then again those that choose to stay or say it won't be that bad probably wouldn't leave unless the beach bar closed down

[brunota2003]

The only thing is that then it would make it too complex...the general public needs something simple, they are not weather loving people and dont wish to really have to study a bunch just to make sense of the warnings. Simplistic is best, imo.

[HurricaneBill]

With the surge levels on the Saffir-Simpson scale, weren't they based on surge levels in Miami?

[vbhoutex]

As for Ike, Galveston and the Bolivar Peninsula were warned that a catastrophic and life threatening storm surge was on the way. Many dismissed the warnings as being either incorrect or "it's not going to happen here" thoughts.

That is true. I know that on Wednesday, September 10th, we were talking about a potential 20-25 foot surge into Galveston Bay with landfall between Galveston and Matagorda. I think the biggest problem was the failure of Galveston's Mayor to take the storm seriously. I was yelling at the TV each time she came on, downplaying the threat. She may have cost some residents their lives. Can't believe she hasn't resigned.

You and me both on the screaming!!! Resign? Her? Are you kidding? She still thinks she did nothing wrong.

[DanKellFla]

What a great idea. Thanks for the post Chacor. People think surge is a "one size fits all" phenomenom. Hopefully, this will help eliminate that kind of thinking.
I know that this is probably too complicated, but I think there should be a scale with three parts. Wind/Surge/Hurricane Wind Diameter (in miles). For example, a big powerful storm that has had a lot of time to push water around would be 1/A/200. A being a big surge. A little storm like charley would be a 4/C/25.