It’s hurricane season in San Diego. This is a rare, but periodic occurrence in Southern California. Hurricane season here is nothing like it is along the Gulf Coast or even the East Coast. The only recorded hurricane to actually get to San Diego was in 1858 and barely qualified as a hurricane (wind speeds of 75 mph when over 73 mph is the speed that defines a hurricane). By the time its outer tendrils reach San Diego, our current Hurricane Hillary is predicted to max out at 50 mph winds and possibly 3 to 5 inches of rain.
Stop laughing all you East and Gulf Coasters, and let me put on my geographer’s hat and explain it to you. First, don’t scoff at 5 inches of rain when our average rainfall for the county is 10 inches, closer to 2 inches on the coast. (BTW for you New York City residents, San Diego County is over 4200 square miles, or, to put it in your terms, half the size of New Jersey, so, yes, rainfall amounts vary quite a bit inside the county. Like LA, we also have 4 different local weather reports, one for each, beaches, inland valleys, mountains, and deserts.)
We build for earthquakes out here, not hurricanes. And yes, even 50 mph winds will blow over trees around here because trees have shallow roots since they have to swallow up any water that hits the ground as soon as it lands. Rainwater never gets a chance to sink to an aquifer. Either the trees and other vegetation slurp it up during the storm, or it heads for the sea. IIRC, we’ve had at least one person die when a tree falls on them in every storm like this. I try to keep an eye out for those killer trees.
Why don’t places on the west coast of continents get hurricanes? It’s all due to this crazy thing called the Coriolis Effect, which is all about this spinning sphere we’re living on. That’s what makes ocean currents circle clockwise, if you’re in the Northern Hemisphere that is. If you’re south of the equator, it twirls the other way. Shake your head until it rattles, but just trust me on this one.
Air is not solid, so the wind blows where it will as the Bible says. Likewise the oceans are not solid either, so they flow as well, just not as fast and unpredictably as the air does. In fact there’s a permanent anticyclone of water streaming past the continents in a giant circular direction. Fortunately for us, being liquid, water circles much more slowly and less capriciously than air does. It’s because it’s slower that it doesn’t suck Hawaii back down to earth’s crust in one giant whirlpool.
What that means though is that on the east coast of continents, the hot tropical water of the ocean current flows towards the pole. On the west coast it comes down from the frozen polar extent of the ocean to slip back down to the tropics along the west coasts of an ocean-fronting continent.
Why is that important? Because east coasts have warm ocean currents from the tropics, making for pleasant beach swimming, but west coasts have cold, polar currents sliding down from the arctic (or antarctic) back to the tropics to start all over again, meaning you better wear a wet suit when you go surfing in California. Warm water (over 80 degrees F) generates hurricanes. Cold water tends to stop them in their tracks. That’s why you can stop a hurricane by dumping about 100 tons of ice cubes into the water in the hurricane’s eye. Don’t believe me? Try it. I’ll wait.
In any case, that’s why west coast hurricanes are more of a nuisance than the menace they are on the east coast. So play your tiny violins in sympathy for us west coasters in hurricane season. At least the surfers will have big, fun waves.
Musings of a Restless Mind 