Do we need a new system for categorizing hurricanes?

Posted: Updated:
(Source: Christopher Boehme) (Source: Christopher Boehme)
(3TV/CBS 5) -

This week, we saw the biggest flood in U.S. history hit Texas. Houston picked up about 50 inches of rain from Hurricane Harvey, with much of the city still underwater nearly five days after it hit. 

Harvey was a storm like no other. But then again, most storms are different from each other. 

Harvey made landfall as a category 4 storm with 130 mph winds. For about a day or two leading up to landfall, the forecast from the National Hurricane Center predicted a major hurricane, a Category 3 storm. People along the coast evacuated, while folks in Houston stocked up on a few days’ worth of food and water. 

But there was continued chatter, debate and some would say focus about the track of Harvey. Everyone wondered which coastal town would take the brunt of the storm. And yet, the exact track isn’t what turned this hurricane into a history-maker.

[MOBILE/APP USERS:  Click here to see the AP picture of Houston homes underwater]

Harvey became “trapped” between two areas of high pressure. Typically, tropical systems are directed by different air masses that push or pulls them one way or another. But in the case of Harvey, the storm had nowhere to go. So after Saturday morning’s landfall, it continued to dump heavy rain throughout Saturday, Sunday and Monday, leading to widespread flooding. Most of that time, it was just a tropical storm since it lost its strong wind speeds after coming onshore. 

Still, as just a tropical storm, Harvey dumped the most rain ever recorded for a tropical storm or hurricane in the continental U.S. And that has led to some debate this week in the meteorological community. 

Does it still make sense to rank hurricanes by wind speed? The traditional Saffir-Simpson scale classifies storms by miles-per-hour wind speeds. But two storms that are both the same category can have very different impacts since winds aren’t necessarily what prove to be the most dangerous. 

[MOBILE/APP USERS:  Click here to see the Saffir-Simpson Hurricane Wind Scale]

When it comes to storms, you have to look at winds, the storm surge and inland rain. Depending on the area hit and the strength of each of these factors, the damage -- and lives lost -- can vary greatly. 

Now, some meteorologists are saying it may be time for new, upgraded scale which would better represent the danger of future storms. Already, there have been improvements to the communication between the National Hurricane Center and the public. For the first time ever, the NHC issued “storm surge warnings” ahead of Harvey. There’s been a big push over the past few years to get the public to understand the danger of a storm surge. 

Scientists at the National Center for Atmospheric Research (NCAR) last year proposed a new index called the Cyclone Damage Potential index -- or the CDP for short. The researchers looked at a potential hurricane’s size and speed, along with winds. That index isn’t widely used though. 

Certainly, there are many lessons to be learned from Harvey over the next few weeks, months and years. But this disaster definitely highlights that there are unique threats to each storm, the importance of forecasters communicating those dangers and the public recognizing the risks particular to each storm.

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