(*Chip Merlin’s Note–Rocco Calaci has been a noted meteorology expert witness in the Katrina Legal Wars. I met him at a recent FAPIA Convention where he presented a speech about hurricanes. I invited Rocco to write on today’s topic after he briefly mentioned it in his speech.)
Since the release of the Saffir-Simpson Scale in the late 1960’s, it has been considered the “standard” in how hurricanes have been categorized. It is my personal opinion that the Saffir-Simpson Scale is no longer relevant due to new technologies and the fact that the estimated levels of destruction rarely match the actual destruction observed from hurricanes over the past decade.
The use of the Saffir-Simpson Scale, along with other meteorological “beliefs”, must be put aside and replaced by factual and verifiable research.
An interview conducted by Ms. Debi Iacovelli in 1991 with Dr. Robert Simpson revealed the co-author’s thoughts on the hurricane scale carrying his name. In the interview, Dr. Simpson stated that “It’s [the Saffir-Simpson Scale] been misinterpreted, misused in a lot of places.” He also added “The scale as devised, expresses what the extreme conditions can be expected from a hurricane of a certain type and a certain category.”
This means with a Category 3 hurricane the extreme level of damage and destruction should be “[s]ome structural damage to small residences and utility buildings with a minor amount of curtain-wall failures. Mobile homes are destroyed.” Yet time and time again, post storm observations prove that a Category 3 hurricane is capable of causing extensive and widespread damages to structures.
Hurricane Ivan (2004) was listed as a Category 3 hurricane, yet the level of damage and destruction equaled a Category 5 on the Saffir-Simpson Scale. In fact, if you read the expected level of damage for a Category 5 hurricane, it states that “Massive evacuation of residential areas may be required.” Obviously the Saffir-Simpson Scale infers that massive evacuation isn’t necessary for any hurricane below a Category 5. Tell that to the people that died in Hurricane Katrina (2005) and it was listed as a Category 3 hurricane.
Another factor on why the Saffir-Simpson Scale should not be used is the differences between it and the Beaufort Wind Scale. The Beaufort Wind Scale is still used extensively throughout the world and has been accepted by the World Meteorological Organization and the National Weather Service. The Beaufort Wind Scale is contained in the Federal Meteorological Handbook Number 1, Surface Weather Observations, considered the “bible” for surface observations.
Time and time again, we see that the Beaufort Wind Scale (BWS) is more accurate than the Saffir-Simpson Scale. The BWS lists winds from 55 to 63 miles per hour capable of uprooting trees and causing considerable structural damage.” Conversely, the Saffir-Simpson Scale states that winds must be stronger than 96 miles per hour to uproot trees and stronger than 110 miles per hour to cause considerable structural damages. Why the disconnect?
It is my personal experience with Hurricanes Erin, Opal (1995), Danny (1997), Ivan (2004), Dennis, Katrina and Rita (2005), that trees were uprooted with regularity when the sustained winds were below 90 miles per hour. During Hurricane Opal, I stood outside the weather station at Eglin AFB, Florida (I was the instructor-meteorologist in an Air Force position) and the winds were consistently sustained below 90 miles an hour for the majority of the storm, yet I witnessed large trees uprooted and blown down streets, concrete block buildings torn apart and large roofs ripped from structures creating massive amounts of flying debris. Hurricane Opal was categorized as a Category 3 hurricane, but the destruction level was likened to a Category 5 storm.
The Saffir-Simpson Scale does not take into account the speed of movement or storm size to categorize a hurricane. If a structure endures hours and hours of battering from winds between 75 to 90 miles an hour, it will still suffer extensive damages. The Saffir-Simpson Scale has no explanation for such elements such as wind shear, ground turbulence, microbursts and vortices.
Everyone becomes fixated on the highest wind speed and associated storm surge, yet the Saffir-Simpson Scale makes no provision for length of time a structure is affected by hurricane force winds.
I like to use the following analogy for hurricane damage. A house endures hours and hours of hurricane force winds and all the associated “forgotten” elements such as wind force, wind shear, ground turbulence and other forces. After several hours, the house is destroyed, but with the area evacuated no one witnesses the destruction. The storm surge arrives hours later and sweeps away the debris from the destroyed home. After the hurricane, folks come back and see the flooding and standing water and assume all damages were created by the storm surge.
Even when there are eyewitnesses to the destruction, records indicate storm surge as the factor in destruction of properties.
When Hurricane Katrina hit the Mississippi coast line, the central pressure fit into Category 4, the storm surge was a Category 5 element, yet the winds were only estimated as Category 3? There is a definite disconnect.
Of course, we are limited in what elements are accurately measured because less than 1% of the affected area in Hurricane Katrina had any type of reliable weather measuring equipment. The sparseness of meteorological data only fuels the ongoing battle of what element caused the initial and primary data: the wind or the water.
The Saffir-Simpson Scale was developed in the 1960’s when meteorological radars still depicted large black blobs on the radar screen instead of the color-diversified images from NEXRAD. In the 1960’s we had limited knowledge of hurricane dynamics and today we have the technology to measure a variety of storm elements.
Some scientists say it makes little sense to hew to an older warning scale that doesn’t take into account the wealth of hurricane data collected.
Among them is Mark Powell, an atmospheric scientist for the National Oceanic and Atmospheric Administration’s hurricane research division. Powell has developed a system of measuring a storm’s potential destructiveness that he calls integrated kinetic energy. The technique essentially sums the strength of a storm’s winds and the size of the wind field. (Houston Chronicle, November 29, 2008).
During my years as a meteorologist, I was taught that research results arrived only after years of analysis and collected data, yet there is no archive of what data was used to generate the Saffir-Simpson categories. What was the thinking of the authors of the scale when they determined the different categories and the expected levels of damage? Why aren’t these inconsistencies corrected by the development of a more factual scale?
The people who work at the National Hurricane Center and National Weather Service are over-worked and under-funded, yet the American public expects miracles each and every time a hurricane closes in on the United States. When a hurricane warning is issued, the public becomes convinced that the level of damage associated with the current hurricane is what can be expected. This just isn’t true!
It is a shame that the United States doesn’t have a better system of collecting meteorological data to provide better resolution for numerical models in forecasting hurricanes. It’s a shame that the Saffir-Simpson Scale is used blindly by various agencies to rationalize their decisions in wake of a hurricane.
The overblown damage expectations and associated wind speeds in the Saffir-Simpson Scale are extravagant. When Hurricane Ike made landfall in Texas it was classified as a Category 2 hurricane with sustained wind speeds of 110 miles per hour. I can not believe that the hurricane and associated properties understood what was expected of them. Do you think any structure realizes that one more mile per hour of speed would be a Category 3 hurricane and then it was permissible to show signs of minor damage?
We must wake up to the fact that many of our popular meteorological beliefs have no substance or real support. One of favorites is the “belief” that storm surges cause the most damage and deaths in a hurricane. Where is this supported by real numbers? Does any agency (FEMA, NWS, Census Bureau) actually count the number of deaths from wind versus surge? The answer is NO!
Many of our “beliefs” are carryovers from the past when all the deaths were lumped into the category of “storm surge related”. I will back off from my rants if any agency can provide me with a list of hurricane related deaths (along any coastline) that is categorized for wind-related versus surge-related deaths.
In summary, our entire system of categorizing hurricanes with the Saffir-Simpson Scale is misleading and inaccurate. I am sure that a better system for categorizing hurricanes can be developed, but can this effort withstand the politics of such a venture? You can be sure that before another system replaces the Saffir-Simpson Scale, the political battles within and outside the meteorological community will add years before the public has a new method to confront the dangers of hurricane landfalls.
–Rocco Calaci
