I’ll make this pretty brief, but figure some people will have interest in a short post rather than waiting for a longer one. The quiet hurricane season ended today with the emergence of Dorian. What seemed like a benign tropical storm is getting a perfect ride through the Caribbean and looks likely to dodge most of the islands on the path to Florida.
By avoiding land, Dorian will be able to keep all its strength and even intensify as it heads towards Florida. The National Hurricane Center is now projecting a cat 3 on the east coast of Florida for Monday. A lot can obviously change between now and the weekend so hard to have too much confidence in this forecast.
However, we can have confidence in one thing. This storm won’t surprise us and head out to sea. I’ll try to concisely explain why.
What Causes Landfalls?
To state the obvious, Atlantic hurricanes can do one of two things as they move west: keep heading west until they hit land or curve to the right and head out to sea. Most storms recurve. It is what they want to do (based on the rotation of the Earth).
To not recurve, something has to get in the storm’s way to block it. That thing is typically a ridge called the Bermuda High. Think of it as a wall that sits in the ocean. A storm can’t turn north if it runs into a wall every time it tries. Therefore, it will default to continue heading west.
However, it will keep trying to turn north every chance it gets. Think of it is as a simple computer program.
- Try to go north.
- If blocked, take one step west.
- Try to go north again.
- If blocked, take one step west.
The storm will keep seeking out that path north. Most of the time it eventually reaches the end of the wall and can go north and recurve. Sometimes, it can’t. This is when storms make landfall on the East Coast.
The Wall Blocking Dorian
You can see below what is happening with Dorian. There is no place for the storm to turn north. There is a giant wall in its way. The furthest north it can get if it’s really persistent is Georgia.
Will The Wall Stick Around?
The real risk is that this high stays in place for the next few weeks. If that happens, any new storms that come along will also have no ability to recurve. That is what caused the disastrous 2004 hurricane season. The Bermuda High moved very close to the coast leaving storms no option other than to hit Florida or move into the Gulf. It is possible that is the scenario we are looking at for the remainder of 2019!