7.3 Size Matters. Why We Should Be Adding a Size Component to Hurricane Scales

Friday, 23 June 2017: 2:00 PM
Salon III (InterContinental Kansas City at the Plaza)
Athena Masson, University of Toronto, Scarborough, ON, Canada

Broadcast and government meteorologists are familiar with the Saffir-Simpson Scale and relay this information to the public in a timely fashion. The public computes the information based on The Scale’s 1-5 category system. However, the public does not translate entirely the meaning of the 1-5 numbers. Meteorologists take complicated measures of the intensity of a hurricane and compress it to a simple form in which the public can reasonably understand. However, the science behind the analysis of a hurricane is dwindling and as a result we are not examining a hurricane accurately enough to protect and inform the public.

 1973 marked the first introduction of the Saffir-Simpson Scale to the general public. Wind, storm surge, and barometric pressure have been the three main components to assess the intensity of a system. However, the scale has failed to look at the size of a system and how this particular component can determine the severity and the type of hazards that a hurricane will produce.

Wind is not the major threat with every hurricane. Frequently water is the main threat. The size of a hurricane links directly to the components currently found in the Saffir-Simpson Scale. Due to the massive size and extensive cloud cover, a large storm is considered to be a water storm with the main hazards including flooding, storm surge, and excessive rainfall. In addition, a larger storm will impact a larger coastal area, and bring it into contact with a larger populous. Comparably, a smaller storm has a greater angular velocity and will generally produce more wind damage. As these winds are sucked in toward the eye-wall they speed up due to the conservation of angular momentum thus intensifying the hurricane. A smaller storm has more angular velocity compared to a larger system and therefore 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 the clouds due to their size, yet their wind speeds make up for this lack of water, especially close to the eye.

This research focused on measuring hurricanes in the North Atlantic from 1978 to 2009 using enhanced infrared radiation satellite images taken at the time a hurricane reached its peak strength (lowest barometric pressure). Warm and cold core radial and area measurements were recorded for each cyclone formed based on cloud temperatures. Short and long radial distances were recorded along with area measurements to determine the approximate size of a cyclone and the shortest/longest side to a storm.

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, broadcast 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 synoptic scale storms, agencies can gain life saving information just by approximating the size of a system.

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 the original scale specifically for public awareness and to help save lives. All meteorologists share this common goal. Meteorologists, both at the government level and broadcast level, need to somehow incorporate the size of a system into their warnings. We want to be ready for the next severe weather event. With hurricanes 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.

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