5 October 2022
A hurricane or tropical cyclone forms from a low-pressure system combined with thunderstorms in tropical or subtropical waters. The warm oceanic air fuels the storm and surface winds move in a circular pattern, called a closed circulation. While the center or eye of the storm is calm and clear, the area that immediately surrounds the eye, or eyewall, contain the strongest winds. The wind speed is what classifies the storm:
- Less than 39 mph = tropical depression
- Between 39 and 73 mph = tropical storm
- At least 74 mph = hurricane
Major hurricanes have wind speeds of at least 111 mph, will reach speeds over 180 mph, and have gusts around 200 mph.
So, what happens is a group of thunderstorms create a disturbance in the atmosphere? Then a specific recipe needs to be in place of warm ocean waters, temperatures drop as you go higher into the atmosphere, with moist air in the middle, a vertical wind sheer (which is a calm wind as you go higher), and within 200 miles of the equator.
All of this warm air holds extreme amounts of water, which becomes rain as the air cools. That is why hurricanes produce so much rain that it will cause flooding, not only along the coast but inland as well. All of the winds cause a tremendous amount of damage but water surging becomes an ongoing concern for quite some time after the storm has passed. That is why anyone should avoid returning to the area until the official all clear is released. Roadways can flood quickly and low-lying areas take even longer to drain.
Hurricanes also spawn inland flooding, tornados as well as coastal rough surf and rip currents. With climate change, you can expect to see a corresponding change in their effects. Scientists and volunteers are tracking and trying to predict what we can expect in the future.
Every storm is different. Even if you survived a previous hurricane in the same area, there is no guarantee that another storm will act the same way. Believe evacuation notices and be prepared to leave when they are issued.
If the untoward does happen and you are caught in a hurricane, shelter in place in a sturdy structure, away from windows and doors, on as high ground as you can. After the storm has passed, there are still dangers from downed power lines, shifting debris, and sudden water surges and flooding.
By the way, hurricanes, typhoons, and cyclones are all the same type of storm. It just depends on where they originate. Once it is classified as a tropical storm based on winds, the World Meteorological Organization (WMO) gives it a name. Using short, distinctive names makes the storm more easily identified and is less confusing in the media.
The names are reused every six years, unless the name has been retired because the storm was particularly deadly or costly in its impact. During World War II the storms were given female names and in 1950 the National Hurricane Center officially started issuing names like Alpha, Baker, etc. to correspond with phonetics. Then in 1953 they reverted to the female names.
This year we are already up to Ian. After that you can expect to hear about Julia, Karl, Lisa, Martin, Nicole, Owen, Paula, Richard, Shary, Tobias, Virginie, and Walter. If the number of storms exceed that list, don’t worry. They have a back-up list ready to go.
- S. This information was taken from the National Oceanic and Atmospheric Administration (NOAA).