Hurricanes: Categories and Impacts

September 4, 2020 // Article by: Bobby Bianco

How much do you know about hurricanes? 

Let's start with how we classify hurricanes. Meteorologists (specifically the National Hurricane Center) use something called the "Saffir-Simpson Scale". Hurricanes are rated in categories from 1 - 5 using the storm's sustained wind speed and estimates the potential property damage. Category 1 hurricanes are the "weakest" and the intensities continue to increase through category 5. Below are examples of each category of hurricane, types of impacts, and the wind speeds based on the Saffir-Simpson Scale. 

This image of the Saffir-Simpson Scale can be found at https://www.weather.gov/hgx/tropical_scale

 

A lot of people in the Northeast know firsthand what can happen inside a tropical system because there have been several since the turn of the century. Whether it was Irene in 2011, Sandy in 2012, or Isaias in 2020, these were all significant storms with impacts from wind, rain, storm surge, and even tornadoes. These storms were all either tropical storms or low-end category 1 hurricanes by the time they made it to the Northeast. 

Tropical cyclones always have the threat of producing widespread power outages due to downed trees and power lines. Strong winds can also lead to damage to infrastructure, which puts people in harm's way, and even leads to destroyed homes. The result can be millions to even billions of dollars in storm damage. Usually, coastal areas see the worst impacts since they have to deal with storm surge head on, as well as the strongest winds the storm has to offer. Storm surge is simply the rise of ocean water at the shore and just inland. A common misconception is the thought that storm surge is like a tsunami with a huge wave that moves through. That is not the case! It is actually a gradual rise in sea level that continuously pushes inland through coastal locations. For example, if there is 5 - 10 foot storm surge, the ocean gradually rises 5 - 10 feet, it is not a rapid change. If this occurs at high tide, that exacerbates the threat for more widespread flooding.

Now, we'll change directions and look at why wind is one of the most significant threats in the Northeast. As stated before, the coastal locations are usually hit the hardest from storm surge and the strongest winds. The reason that the winds are stronger is because they are blowing over open water and there is little to no friction until they crash onshore. In the Northeast, the region is heavily wooded, with large trees vulnerable to strong winds as hurricanes move inland. There may be some questions about how large trees always seem to go down in strong winds, while smaller ones remain standing. The most likely scenario is that the large trees are bigger and taller than anything around it, catching the most of the wind's force. On the other hand, small trees are many times blocked by buildings or other large objects and do not get the strongest winds directly. 

In addition to wind and storm surge, tropical systems come with a lot of moisture and heavy rain which can result in significant flooding. The most rain ever recorded in a hurricane occurred with Hurricane Harvey in 2017, when it dumped as much as 60.58" in Southeast Texas. That is 5 FEET of rain! An absolutely remarkable statistic, and quite possibly a record we may never see broken again. Keeping up with Atlantic hurricane records, the strongest sustained winds were 190 mph from Hurricane Allen in 1980! Next, the storm that produced the most tornadoes was Hurricane Ivan in 2004 when it produced 120 tornadoes. That is another astonishing record which will probably hold the #1 spot on the podium for quite some time. Lastly, something we are still learning more about with each storm, storm surge. The hurricane with the highest storm surge is none other than Hurricane Katrina when it slammed Southern Mississippi with 27.8 feet of surge. 

One thing to think about is, hurricanes and tropical storms can do a great amount of damage no matter the strength of them. They can all result in power outages and threaten life or property with damaging wind gusts, flooding, and storm surge. If a hurricane does occur and you are along the coast, it would be wise to evacuate and heed any warnings given by government and meteorologists. However, if you are inland, most likely you will not have the same impacts with storm surge, but strong winds, heavy rain and tornadoes may be the main concerns. Always keep in mind the safety of you and your families/friends because it can save lives. 

 

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