900 It's Personal, Size Matters: How Determining the Size of a Hurricane can Better Prepare the Public and Determine the Risks Associated with a Storm
1973 marked the first introduction of the Saffir-Simpson Scale to the general public. Since this time the scale has undergone minor changes and kept three components: wind, storm surge, and barometric pressure. However, it has failed to look at the size of a system and how this particular component can determine the severity of a system and the type of hazards that a hurricane will produce. Wind is not the major killer with hurricanes. Water is the main threat, as we have experienced with notable hurricanes such as Katrina (2005), Ike (2008) and Sandy (2012). The size of a hurricane links directly to the components found in the Saffir-Simpson scale as well as other indicators needed to accurately assess an approaching hurricane. A larger hurricane will theoretically produce a higher storm surge, which will impact a larger coastal area, and bring it into contact with a larger populous. Larger storms produce excessive amounts of rain due to their extensive diameter, which then allows for the wind fields to be spread out further, away from the eye wall. Due to the massive size and extensive cloud cover, a large storm is considered to be a water storm with the main threats being flooding, storm surge, and excessive rainfall.
Hurricane Sandy (2012), known to be the largest Atlantic Hurricane on record, brought the East Coast to its knees, not by wind, but by water. Due to Sandy’s immense size, storm surge and flooding were the main killers and the sole threat of this system. The wind was a very minimal issue. Yet, days before Sandy’s arrival as the East Coast braced for impact, all across the nation news stations and warning centers focused on categorizing Sandy based on the Saffir-Simpson Hurricane Wind Scale.
Unfortunately, Sandy arrived in an awkward year. The National Hurricane Center eliminated pressure and storm surge in 2009 and transformed the Saffir-Simpson Scale into a pure wind scale, dropping the components of pressure and storm surge. The scale excludes storm surge, flood ranges, location, and rainfall, which means a Category 2 hurricane which hits a major city will likely do far more cumulative damage than a Category 5 hurricane that hits a rural area. The National Hurricane Center cited various hurricanes as reasons for the removal of the “scientifically inaccurate" information, including Katrina (2005) and Ike (2008), which both produced stronger than estimated storm surge values (NHC, 2009). Due to this change in the scale, when Hurricane Sandy approached the East Coast of the United States, residents had little information on storm surge values and even more minimal communication on the flooding risk. Sandy was a water storm, and it was because of its size that historic storm surge washed away thousands of homes along the East Coast and killed almost 300 people.
A smaller storm more closely resembles a tornado. The smaller a rotating column of air is, the faster the wind speeds. Smaller storms do not hold enough moisture in their clouds due to their size, yet their wind speeds make up for this lack of water, especially close to the eye. Hurricane Andrew (1992) is a perfect example of “big things come in small packages.” Andrew produced very little damage with regards to storm surge and flooding. Most of the damage was due to the powerful Category 5 winds and not the water content associated with Andrew, and this is proven by examining the extensive damage over inland southern Florida, far from the ocean shore, especially around Homestead.
Size matters in meteorology, especially hurricanes. Whether the National Hurricane Center agrees to incorporate the size component into a hurricane scale or not, governments, emergency managers, meteorologists, and residents, need to understand the threats that come with hurricanes based on their size. Although accurate measurements are imperfect when it comes to measuring hurricanes, agencies can gain life saving information just by approximating the size of a system. This particular research focused on measuring hurricanes in the North Atlantic from 1978 to 2015 using infrared radiation satellite images taken at the time a hurricane reached its peak strength (when a hurricane first reaches its lowest barometric pressure). Several scenarios and suggestions are presented to measure the size of a hurricane based on cloud temperatures.
Gaining insight and understanding on the size of a hurricane can help save lives and enhance our nation’s readiness, responsiveness, and resilience. Saffir and Simpson created their scale specifically for the public and to help save lives. All meteorologists share this common goal. We want to be ready for the next severe weather event. With hurricanes being a threat year after year it is time to step up and analyze ways to protect society and improve the Saffir-Simpson Scale. Let’s start by observing the size, because it does matter.