Background and Motivations for the Saffir / Simpson Scale

Herbert Saffir, a distinguished engineer out of Georgia Tech, was the first to propose a scale to classify the destructive potential of dangerous storm-generated winds. He was a frequent visitor at weekly seminars of the National Hurricane Research Project in West Palm Beach from its earliest days in 1956, and later in Miami where NHRP became a permanent laboratory adjacent to the National Hurricane Center. He and I collaborated over several years on mutual projects related to hurricanes, with his interest being primarily the survival of various structures and mine being the atmospheric conditions that combined to produce high winds. The present scale for assessing the damage potential from hurricanes was originally designed by Saffir and modified by us both in consultation with senior NHC staff. This paper recalls pertinent events and the motivations for incorporating the hurricane damage potential scale to the services and hurricane advices issued by NHC. Herbert Saffir was one of the first to conduct surface surveys and photograph hurricane damage sites for understanding, cataloging and researching the character of hurricane damage. NHC staff also surveyed and photographed hurricane damage, mainly from military helicopters supplied by requests from the Air Force's coordinator of hurricane reconnaissance missions (CARCAH). These two surveys were shared and discussed amongst all concerned and formed the basis for the development of the hurricane scale.

The operational need for a hurricane damage potential scale became evident with the arrival of Hurricane Camille in 1969, during which record breaking winds and 24 ft storm surge had devastated coastal areas of Alabama, Mississippi and Louisiana. Following the passage of Camille, NHC found itself swamped with requests for quantitative information that it was ill prepared to supply. Recommendations for a hurricane scale came from both NHC and NHRL in Miami and from the University of Colorado's annual meetings of natural hazard specialists from across the nation under the able leadership of its Professor Gilbert White.

The focus soon settled on the application of a scale similar to that Saffir had been working on (under contract, as I recall with the United Nations). And during an extended luncheon the use of Saffir's scale exclusively for operational hurricane information and advices at NHC, was agreed, subject to a few specific adjustments of the original.

The scale was amended to supply the corresponding low level pressure for each category. An obvious issue also arose in distinguishing between wind speed maxima for open country and those locally influenced by urban sprawl and high rise environments. Engineering assessment of damaging winds usually recognizes that for many structures the potential wind damage is related to irregular shapes of the structure and the wind gustiness, which are quite different in an urban environment to over open country. Saffir acknowledged this in his publications and expressed the opinion to me that gusts of 10 seconds or less would be a most suitable value for category damaging wind speeds. But in those days there was no archive of such gusts with the major source of data being hourly aviation weather reports. Therefore it was mutually agreed that the category scale would be defined by the highest one minute mean value. The scale was accompanied by a textual description of common place damage associated with each category after hurricane passage over open country or uncluttered suburban areas

The original scale did not include damage owing to storm surge due to its dependence on not just winds, but size, angle of approach to the coast, and local bathymetry. During the period of negotiated adjustments to the original Saffir code a separate surge code was fashioned for internal guidance of forecasters based upon a computed “standard” bathymetry, pending completion of coastal surveys. This was only intended as a stopgap procedure, one that was soon supplanted by the rapid advances in surge modeling and understanding.

The revised scale, after surviving the customary headquarters reviews, was released by NHC for restricted operational appraisal in 1975, and a year later for public information and application as the Hurricane Damage Potential Scale. Shortly thereafter, on the recommendation of an Annual Hurricane Review Committee comprised of NOAA, Air Force, and Navy members, it was renamed the Saffir / Simpson Hurricane Scale, news of which came as a surprise to both Saffir and Simpson! “Acknowledgements. The above comments and recollections of some of the more memorable episodes of my widely varied career in meteorology, probably would never have been recorded if it had not been insistently proposed by my close friend and colleague Greg Holland, who reminded that after more than three decades of widespread use, there remained some uncertainties regarding the background, and motivations for some of the definitions employed in the Saffir / Simpson Scale. As written it is intended as a tribute to Herbert Saffir. And if he had lived, I am sure he would have been pleased to co-author these explanations. Finally, but significally, Joanne Malkus Simpson, (my late wife) weighed in during our informal daily discussions, influencing my own reasoning concerning final construction of the scale before its release for public usage”.