I'm a CMU Honors student and love meteorology and extreme weather. I've been fascinated by weather since I was 5, and plan on becoming a meteorologist
By: wxchaser97 , 5:27 PM GMT on September 26, 2012
Hurricane Isaac had a big impact on many lives in the US and around North America. Isaac has caused lots of damage in the US and Caribbean islands. In the US alone so far $2 billion dollars in damage have been done with 9 fatalities. In all Isaac has caused over $2 billion USD in damage and over 40 fatalities. These numbers, at least damages, are expected to rise as more surveys go on. Many homes were lost to the surge, flooding, and wind. Surge was up to 14-15ft, up to 20" of rain fell, and 80mph winds blasted the coast. While at first Isaac was forecasted to strengthen into a strong cat2 he was never able to. Too much dry air and a lack of a central core prevented any strengthening in the gulf until landfall. When Isaac was making landfall his structure improved and winds came up, but his size/surge would be the biggest problem. Many were caught off guard when Isaac came in as he wasn't supposed to "be a strong hurricane". Many people will never forget hurricane Isaac and it is possible the name Isaac is retired from the hurricane naming list. Isaac was a difficult storm to forecast and left forecasters thinking. No one had really expected Isaac to not strengthen or take the path he did. What I want to address is the problems with the current hurricane rating system and propose a new one.
Explaining the Saffir Simpson scale
This is the current scale that rates tropical storms and hurricanes. It is mostly based off of just wind speed and doesn't provide much info on storm surge and rain. The scale is broken down into separate categories based off of how strong the winds are. The categories in the scale are tropical depression, tropical storm, category 1 hurricane, category 2 hurricane, category 3 hurricane, category 4 hurricane, and category 5 hurricane. A tropical depression is pretty weak and a tropical storm has some rain, wind, and surge. Hurricanes are further branched of into the numbered categories of 1-5 with 1 being the weakest and 5 being the strongest and 3 or higher is considered a major hurricane. This scale is the official hurricane scale for the Atlantic Ocean and the Eastern/Central Pacific Ocean. Storms usually form from tropical depressions and then strengthen and go higher on the scale. However, we get exceptions to this or storms expose flaws in our current scale which needs to be fixed.
What went wrong with the SSHS
Hurricane Isaac is only the latest example to show problems with the SSHS. Some other examples would be Ike, Charley, and even Katrina has shown things with the SSHS. What we have seen is that a really large storm may not have as strong of winds as the pressure indicates, but have a big storm surge. A small storm may have strong winds but little storm surge. Also extreme amounts of rainfall dropped from some storms is not taken into account. Thus a false warning is sent out to the public and this could be potentially fatal. Isaac has been a costly reminder that it is time to change how we rate/forecast our storms. It could've been worse with Isaac, but it was still very ugly. I feel now is the time to begin to change before another storm comes along and things don't go to plan.
How to fix/change the SSHS and my proposed scale
As I have already said, the Saffir-Simpson Hurricane Scale needs to be changed. To get people more aware of the dangers and to more accurately rate storms I have made changes. I call my scale the Modified Tropical Intensity Scale. First I have changed the wind speeds just a little from the SSHS to my scale, the MTIS. It is just so I can adjust the categories around a little and so the is a more uniformed increase in winds. My second change, a big one, is to add a new category. Usually tropical storms are downplayed even when the reach the upper limits so I want to address this. The severe tropical storm category is the upper level of a tropical storm and people will take it more seriously. I have based this off the Western Pacific using a similar thing and I liked the idea. Then I had to take care of the storm surge and rainfall issue. I have 3 columns in my scale and they are wind, storm surge, and rainfall. The MTIS mostly focuses on wind and surge but also includes rainfall in the decisions. Hopefully this will more accurately indicate the strength of a tropical storm or hurricane. Finally I have created a points system to help rank where a storm or hurricane goes. There is some flexibility with this part but usually it should work out fine. I am hoping this would be a better solution than the Saffir-Simpson Hurricane Scale.
Comments and suggestions would be great so I can look at any initial flaws and make improvements. Have a wonderful Wednesday everyone! I will have a tropical update later today but a link to this blog will be at that one.
The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.
Comments will take a few seconds to appear.