This is just a quick post to suggest an answer to the question posed by Greg Laden here: should we have a category 6 and above for hurricanes. My answer is no.
I say this in agreement with many of the points expressed in Greg's post, mainly that category 5 basically means total destruction and for all practical purposes what is the difference between flattened like a dirt road or flattened like a paved one? But in acknowledgment of the other arguments and points of view, I would suggest further categories into the higher wind speeds in the form of Category 5A, 5B, 5C etc. It seems to me this would satisfy all concerns on both sides with regard to distinguishing between increasing extremes of measured wind speeds and not diluting the "run for your life" message category 5 is supposed to deliver.
Getting into the weeds a bit further, it is a very valid additional issue that wind speed is not the whole story, and very often not even the most important part of the story. Anyone remember how Katrina was "only" a category 3 hurricane when it made landfall? Super Storm Sandy was a mere category 2 when out at sea getting ready to pound the eastern seaboard. Not much to worry about in those instances I guess. Wrong. In addition to destructive winds, hurricanes bring storm surges and tremendous rainfall, both of which can pack a worse destructive punch than the direct effects of wind.
So perhaps we should assess a hurricane on at least two additional impact factors: storm surge and rainfall and thus categorize them in three independent ways. If so, it should be consistent, 1 to 5, plus 5A to 5-what's the point again??
What do others think?
(Update: Eli Rabett asks the same question)
That is an interesting idea.
If the main reason to categorize a storm is to gauge its potential damage to human life and property, maybe the categories should be based on that. It would mean that storms with the same strength might be in different categories depending on whether they can or will come ashore. Potential to cause damage obviously depends on all the factors you mention. If, on the other hand, the categories are simply to gauge strength, then they should be based on some measure of that -- wind speed seems reasonable for that.
Maybe the storm category should settle for the danger or damage for things that are not modifiable by human endeavour.
I.e. if you were standing outside and you were 99.9% chance likely to be picked up and bodily hurled to your death, that doesn't change if you improve building codes.
If 100 year old established trees have a 50:50 chance of being uprooted, that isn't changed (much) by humans building stuff in the area.
Then buildings could be built to transfer the "practically certain death" to a "one-in-a-thousand" chance of failing to protect (by, for example, collapsing in the high winds) of a Category-X storm, or built to do the same in a Category-Y one.