UCSB Science Line
Sponge Spicules Nerve Cells Galaxy Abalone Shell Nickel Succinate X-ray Lens Lupine
UCSB Science Line
How it Works
Ask a Question
Search Topics
Our Scientists
Science Links
Contact Information
How is that the Caribbean islands, the Gulf of Mexico and the East Coast get all the hurricanes? How we do not get any here in the West Coast of California?
Question Date: 2018-09-14
Answer 1:

Short answer:
It's because of the California current off the west coast (which is cold) and the Gulf Stream off of the east coast (which is warm). Hurricanes lose strength over cold water, so they die before they can make landfall in California (although I have been in the eye of a remnant hurricane that made it into central Nevada!). The reason for these currents being where they are has to do with the Earth's rotation.

Long answer (hint: you may want to ask your junior high science teacher to explain parts of this with a globe):
The Earth spins from west to east. Because the equator is farther away from the axis of the Earth's rotation (which runs from pole to pole), the surface of the Earth on the equator is moving faster than the surface farther from the equator, and isn't moving at all on the poles. The ocean, being fluid, experiences drag due to contact with other parts of the ocean. This means that the ocean at the equator is slowed down in its rotation and rotates slower than the rest of the planet because it is experiencing drag from the parts of the ocean farther north and south. This has the consequence that, relative to the continents, the ocean at the equator has a current that is flowing from east to west, opposite the direction of Earth's rotation.

When an equatorial ocean current hits (the east coast of) a continent, it is deflected both to the north and to the south. Being on the equator, this current is warm, and so brings tropical warmth and with it tropical weather (such as hurricanes) along the eastern coast of the continent. As the current it continues to flow toward the pole, it eventually has to turn east as it gets to the pole. Then, when this eastward-flowing polar current hits (the west coast of) a continent, it can only be deflected back toward the equator, flowing along the continent's west coast. Now, of course, it's been flowing near the pole, and so is cold, and brings polar weather (such as coastal fog) to the west coast of the continent.

The California current off of the California coast is flowing south from the Gulf of Alaska, and is therefore cold. The Gulf Stream along the east coast comes out of the Gulf of Mexico, and is therefore warm. Hurricanes over warm water gain strength, so hurricanes can still be strong when they hit the east coast. Hurricanes over cold water lose strength, so by the time hits California, it's just a rotating mass of thunderstorms without a whole lot of powerful winds. The former hurricane that I drove through in Nevada was still recognizable as having once been a hurricane because the thunderstorms were arranged in curved arcs, and I knew when I was in the eye because I could see the storms around me in a circle, but there were gaps between the storms that I could see between them.

Answer 2:

The disparity has to do with the typical weather patterns in the Atlantic and Pacific Oceans. Hurricanes form near the tropics. The prevailing winds (essentially the direction that they blow most of the time) at those latitudes in the northern hemisphere blow from east to west. This means hurricanes are blown toward the east coast of the US, but away from the west coast.

Water temperatures also play a role. The Gulf is typically quite warm, which helps to maintain hurricanes. Water off the west coast tends to be colder, and this reduces the strength of any hurricanes which do come through.

Answer 3:

Hurricanes form in warm, moist air over warm water. Oceanic currents in the northern hemisphere circulate clockwise, so warm water from the equator flows to the Caribbean, Gulf of Mexico, and the East Coast, while cold water from the arctic flows to the west coast. The warm water in the east provides lots of energy and humidity for hurricanes to form, but in the west, the water is too cold.

Answer 4:

This site says hurricanes in the Northern Hemisphere move west, so hurricanes in the Atlantic Ocean hit the East Coast of the US, but hurricanes in the Pacific Ocean move away from the West Coast of the US -

Click Here to return to the search form.

University of California, Santa Barbara Materials Research Laboratory National Science Foundation
This program is co-sponsored by the National Science Foundation and UCSB School-University Partnerships
Copyright © 2020 The Regents of the University of California,
All Rights Reserved.
UCSB Terms of Use