New Hurricane Rating System ?

[J Kinkaid]

http://www.cme.com/files/chi_whitepaper.pdf

[MClarkson]

The SS scale for hurricanes only ranks wind... so why not just include surge as well? IE a hurricane is rated based on its current windspeed or expected surge, whichever is higher. Nothing more complex than that is needed for the general public.

[IAN GIAMMANCO]

Just wanted to chime in with my first post on the forum, in regards to a new hurricane rating system, I believe Mark Powell from NOAA-HRD has a new paper comming out in BAMS sometime soon. He attempts to account for size of the system as well as maximum sustained winds in some type of destructive potential scale. I don't know the details but I believe it will be published soon.


Ian


Ian Giammanco
PhD Candidate
Wind Science and Engineering
Texas Tech University

[richhorodner]

As it is now, when a hurricane warning is issued, the maximum winds (with concurrent category #) are mentioned: PLUS the potential tidal surge in feet above normal in various areas to be affected is forecast.

A big problem with including tidal surge potential in a new "rating" system is that one specific hurricane coming inland will produce widely varied tidal surges along the target area: depending on the slant of the continental shelf, shape of any bays or inlets, speed of forward motion, angle of approach to the coastline, breadth of the hurricane force winds, size of the eye, length and time of fetch, phase of the moon and its distance from the earth at the time, the time of the high and low tides, etc, etc, etc.

For example: a hurricane coming north through Florida (like Ernesto's track last yr.)

http://upload.wikimedia.org/wikipedia/commons/thumb/5/5c/Ernesto_2006_track.png/616px-Ernesto_2006_track.png

Let's say a hurricane with max. sustained winds of 130 mph takes the above path. The tidal surge potential on the east coast of S. Florida with this storm would be about 12 feet; but on the SW Florida coast, this same storm could put 18 feet of surge. In the Florida Keys, the tide potential might only be 10 feet, because they are islands, and some of the surge tends to flow around the small land masses. The higher tides on the SW coast are due to a very shallow continental shelf.

To try to word the warning/advisory to reflect a different "category" for a combination of wind and surge potential would necessitate a different category forecast for each of the many varied locales along the projected path. This would just cause additional confusion.

I think the current system is good and "simple" enough for a panicking public to grasp to some extent. The warning/forecast that mentions the surge potential in each area is already in use; and reflects the potential dangers in each area under a warning.
---------------

Until the 1960's, before Saffir-Simpson, tropical storms and hurricanes were "rated" with 4 categories: minor (less than 74 mph), minimal (74-100mph), major (101-135), and extreme (136+ mph). The newer system added one more category. It took years for the general public to "grasp" this new system: and I believe it has served the public well.

If it ain't broke, don't fix it. The potential surge for each area is already emphasized in hurricane warnings.

Maybe a more precise "after the fact" rating, based on damage from wind, surge, and rainfall combined would be helpful to historians.