The Facts About Hurricanes

Flooding following Hurricane Harvey.

I’ve been seeing many posts on social media lately saying Hurricane Irma will be the first Category 6 storm. They point to seemingly legitimate “news” articles to back the claim. So, to debunk them, here are some actual facts.

There is no need for a category 6 on the Saffir-Simpson Hurricane Wind Scale.

The scale, developed in 1971 by Robert Simpson and Herbert Saffir, categorizes storm strength as it relates to wind speed. There are five (and only five) categories. When asked why there were not more, and if any should be added, Dr. Simpson (no relation, by the way) responded, “…[W]hen you get up into winds in excess of 155 miles per hour you have enough… damages that are serious… So I think that it’s immaterial what will happen with winds stronger than 156 miles per hour. That’s the reason why we didn’t try to go any higher than that anyway.” (Mariners Weather Log, April 1999, pp. 10-12)

Saffir-Simpson Hurricane Wind Scale

Category

Sustained Winds

Types of Damage Due to Hurricane Winds

1 74-95 mph
64-82 kt
119-153 km/h
Very dangerous winds will produce some damage: Well-constructed frame homes could have damage to roof, shingles, vinyl siding and gutters. Large branches of trees will snap and shallowly rooted trees may be toppled. Extensive damage to power lines and poles likely will result in power outages that could last a few to several days.
2 96-110 mph
83-95 kt
154-177 km/h
Extremely dangerous winds will cause extensive damage: Well-constructed frame homes could sustain major roof and siding damage. Many shallowly rooted trees will be snapped or uprooted and block numerous roads. Near-total power loss is expected with outages that could last from several days to weeks.
3
(major)
111-129 mph
96-112 kt
178-208 km/h
Devastating damage will occur: Well-built framed homes may incur major damage or removal of roof decking and gable ends. Many trees will be snapped or uprooted, blocking numerous roads. Electricity and water will be unavailable for several days to weeks after the storm passes.
4
(major)
130-156 mph
113-136 kt
209-251 km/h
Catastrophic damage will occur: Well-built framed homes can sustain severe damage with loss of most of the roof structure and/or some exterior walls. Most trees will be snapped or uprooted and power poles downed. Fallen trees and power poles will isolate residential areas. Power outages will last weeks to possibly months. Most of the area will be uninhabitable for weeks or months.
5
(major)
157 mph or higher
137 kt or higher
252 km/h or higher
Catastrophic damage will occur: A high percentage of framed homes will be destroyed, with total roof failure and wall collapse. Fallen trees and power poles will isolate residential areas. Power outages will last for weeks to possibly months. Most of the area will be uninhabitable for weeks or months.

 

The National Hurricane Center also has a graphic to demonstrate the anticipated damages from the different wind speeds.

The SSHWS applies to any cyclone with 74 MPH or greater winds

Category 5 has no upper limit. Since the scale was developed to describe anticipated damages from different wind speeds, Category 5 means near total destruction. Beyond that point, it doesn’t matter if it’s 155 MPH or 190 MPH as was the case with Hurricane Allen in 1980.

Wind isn’t the only damaging force

The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite acquired this image of Hurricane Sandy off the southeastern United States.

Remember Hurricane Sandy? It was only a Category 3. Yet it still caused $75 billion in damages. Tropical Storm Allison (2001) did $9 billion in damage, and was never a hurricane. Conversely, Category 5 Hurricane Emily (2005) did slightly over $1 billion in damage. While Hurricane Katrina, the modern standard by which cyclones are measured, cost 1,836 lives as a Category 5, the Category 2 Hurricane Fifi-Orlene in 1974 cost 8,000 lives.

Typically, more damage is caused by flooding, both by direct rain and storm surge. That was the case with Harvey. That was the case with Katrina.

There are scientific reports, journalism reports, and click bait reports

It is very easy now to make a webpage look like it came from a legitimate news site. Sadly, there are people who use fear tactics to drive internet traffic and get more views for the ads on their page. There are many legitimate news organizations that portray the facts as more precarious than they are to increase viewership. There are also plenty of organizations, especially in my local market, which do an AMAZING job of presenting the facts. But, like with most things, if you want the best information, go directly to the source.

The National Hurricane Center has remarkable resources anytime there are active storms. They also post regular updates to their Facebook Page. For live observation reports, the Hurricane Watch Net provides great resources as well as streaming audio when the net is active.

Be alert, but don’t panic

Pay attention to the directions of emergency management officials. They may paint a grim picture, but their number one job is to keep everyone alive. Things can be replaced. People cannot. If you are ordered to evacuate, evacuate. If the evacuation doesn’t apply to your area, be prepared to shelter in place for a while. Have a Ready Kit. Have a Family Emergency Plan. Be prepared and stay alive.

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Daniel R. Simpson is an amateur radio operator in central Georgia. He is the Emergency Coordinator for Baldwin County ARES as well as a Public Information Officer and Local Government Liaison for the ARRL Field Organization. He has completed numerous trainings from the Federal Emergency Management Agency, National Weather Service, and American Radio Relay League. 

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