Rex Trulove
Quite a few people have wondered why the east coast of the US is much more prone to hurricanes than the west coast. Although the reasons are complex, it honestly isn’t difficult to understand.
Simplifying it a great deal, the main reasons that the eastern US is more hurricane-prone than the west coast is because of ocean currents and prevailing winds.
Tropical depressions, tropical storms, and hurricanes are spawned by the warmest few inches of water at the surface of the ocean. The storms gain energy and strength in warm water. Conversely, they lose energy and strength in cool water. In fact, this is why hurricanes tend to lose strength just before landfall and even more after they move over a land mass. Water very near land is often cooler than water that is farther out to sea, with the Gulf of Mexico being an exception.
There are a number of strong surface currents in the oceans. For simplicity, these can be thought of as ocean rivers because the sea water is moving, relative to land. The currents are responsible for carrying warm water from the tropics to the polar regions and also carrying cold water from the polar areas toward the equator. There are also deep-sea currents, but these have little to do with hurricanes.
If the earth was stationary, these currents would move primarily north and south, though they would need to flow around land masses. The earth rotates, though, and this causes both ocean currents and winds to move in a roughly circular pattern.
This means that storms that begin in the tropical waters of the Atlantic Ocean move toward the northeast. This carries the developing storms toward the east coast of the US, which means that hurricanes are prone to strike this area unless the currents veer back out to sea. This can and does happen because the currents aren’t stationary.
What about the west coast? The Pacific Ocean also has currents and as with the Atlantic, they move in a circular pattern, first toward the northeast. Thus, most developing storms are carried away from the west coast of the US.
Additionally, there are two strong but opposing currents that move along the west coast. El Nino is a warm current and La Nina is a cold current. Both of these are always present, but the relative strength of each varies, so we can have El Nino years and La Nina years.
Both of these currents normally occur well off the coast and El Nino tends to be the strongest. During an El Nino year, the warm current moves closer to land, pushing the cold water on the landward side with it. The compressed cold water creates a buffer zone so that even if a hurricane forms close to the west coast and moves in that direction, it normally loses strength before it reaches land and rarely makes landfall as a hurricane.
In a La Nina year, the opposite happens and the cold La Nina current pushes warmer water toward the coastline. The warm water can fuel a hurricane, so when hurricanes do make landfall on the west coast, it is usually during a La Nina year. In a particularly strong La Nina year, such as happened a few years ago, the storm can also move substantially farther north.
Again, this happened a few years ago when the La Nina current was strong and brought hurricane-force winds to northern Oregon and southern Washington state. There were also tornadoes and waterspouts caused by that storm.
At any rate, the reason that hurricanes are more apt to strike the eastern US coast than the west coast is because of how the currents behave and move. Incidentally, this applies in other areas of the world, too, and it is the reason that the Philippines are prone to typhoons. As the saying goes, it is location, location, location.
Very informative post. I teach on-line and many times the science textbooks don’t have enough information about hurricanes. I will use this post to help me to explain in a better way.
Thanks for posting.
That is a huge compliment. Thank you! Please feel free to use the information and I hope that it is helpful.
A long time ago I noticed that textbooks aren’t great for actually teaching people. If they do contain adequate information, they tend to talk over the heads of the reader without explaining much and without making much of an attempt to use layman’s terms that would be understandable to the average person.
I try to explain rather than lecturing. That approach served me well when I was a computer technician and technical engineer. It isn’t enough to tell people what they should or should not do on their computers. They’ll forget that 90% of the time unless you also tell them WHY they should or should not do something on their computer. LOL
Thank you for sharing the reason that the Eastern part of the U S gets rocked a lot more than the West Coast.
You are quite welcome. I’m sure that this is something a lot of people have wondered, particularly during hurricane season.
I have always wondered why the Pacific hurricane do hit lower Mexico and then move near Hawaii.
The surface current map helps to show the reason. The current that flows out of the Gulf of Alaska and down the North American coast veers to the west when it gets roughly even with Mexico. Tropical storms rarely move north of that point, except in years when there is a strong La Nina current.
Thank you for sharing that answer with me. I learned a lot.
I appreciate the science behind this presentation. But it reminded me of a childhood memory. My sister is passed away now but I can remember as a child she used to try to simplify explanations of complicated things for her little sister. I remember making a comment about why we (people living in Florida) had so many hurricanes. She quickly remarked: “In California they have earthquakes.” It took me less than a second to decide that I would rather experience a hurricane than an earthquake. I was satisfied with her response and that was the end of the discussion. LOL.
I could see how that would be a satisfying response. I’d thought I might explain all of this mostly because it was asked elsewhere. I’d once wondered about it, too. Then it occurred to me that southeast Asia, pretty much directly across the Pacific from the west coast, did get hurricanes frequently. They just didn’t call them hurricanes. LOL Of course, the Philippines and Japan also get plenty of earthquakes, too.