With the disaster in the Philippines wrought by super typhoon Haiyan, once again the unseemly arguments appear about exactly how fast the winds were blowing at landfall and aw gee there were worse storms, the damage to global GDP was minor. Eli however, and some others have another question. Would it be useful to reformulate the Saffir-Simpson scale? Actually two. Would it also be useful to coordinate the new Saffir-Simpson scale with the Enhanced Fujita scale for tornadoes?
The argument, at least the one the Bunny is making, has nothing to do with climate change, and everything to do with policy, construction codes, public safety and history. Both the Saffir-Simpson and the Fujita scales were designed for public officials to use in determining how to react to cyclones and tornadoes. The ranks are set not so much by wind speed and other parameters such as precipitation, as to the expected damage that a storm would do.
Eli will argue that forecasting and construction progress has overtaken the Saffir-Simpson scale and it is time to revise it. Moreover, while there are few places which are subject to both hurricanes and tornadoes, a uniform scale would prevent the public from perceiving a lesser/stronger danger when warnings are issued. The Fujita scale itself was revised in 2006 with this in mind by the Wind Science and Engineering Center at Texas Tech
Although the Fujita Scale has been in use for 33 years, the limitations of the scale are well known to the users. The primary limitations are a lack of damage indicators, no account of construction quality and variability, and no definitive correlation between damage and wind speed. These limitations have led to inconsistent rating of tornadoes and, in some cases, an overestimate of tornado wind speeds. Thus, there is a need to revisit the concept of the Fujita scale and to improve and eliminate some of the limitations.
|FUJITA SCALE||OPERATIONAL EF-SCALE|
|F Number||Fastest 1/4-mile (mph)||3 Second Gust (mph)||EF Number||3 Second Gust (mph)|
This history is important, because defenders of the Saffir-Simpson scale, including Saffir, claim that there is no need for a category over 5, because at 5, nothing is left.
Eli has seen one reaction from a hurricane forecaster which is typical
CAT 5 is already catastrophic. What is to be gained by our making a distinction between catastrophe and armageddon?Eli begs to differ. Nothing is left maybe, with the construction techniques of 50 years ago. Even in favelas, third world shanty towns, there is the occasional masonry building, and especially with roof straps and other techniques, such buildings can be used as shelters from low end Category 5 storms. With more money, bunnies can hurricane proof their burrows, but when hit with a > 200 mph gust, well. . .
CAT 5 landfalls are rare, three times in a century for the US. When there is a clear forecast of a CAT 5 hurricane landfall, motivation levels are already so high that additional stimulus is likely to produce a decline in rationality and performance among evacuees. Even if a hurricane were to reach CAT 6 or 7, it would most likely be weakening by the time of landfall. Since the object of the game is to communicate with people in a way that helps them make life saving decisions, we don't want to redefine the SS Scale in a way that exaggerates the hysteresis in public perception that already occurs when a formerly very intense weakening---but now weakening---hurricane approaches landfall.
And thus the need
UPDATE: For a somewhat different POV which reaches the same conclusion see Climate Crocks
Coby chimes in