I was always under the impression that evaporated water from the Atlantic Ocean traveled west to hydrate the eastern U.S. and that not only did the western U.S. have to deal with rain shadows from tall mountains, but the wind barely blew in that direction anyway.

Apparently this isn't the case because the prevailing wind direction is almost always west to east. So where the heck is all the precipitation coming from? If it's coming from the west, why isn't it wetter westward than eastward?


1 Answer 1


Why is the eastern United States green if the wind moves from west to east?

The winds don't move straight from west to east. Oftentimes they move from the southwest to the northeast (and sometimes from the south to the north), thereby bringing lots of moisture inland from the very warm Gulf of Mexico. If you want to see green in the continental US, you could go to western Washington. Or, you can drive along the US Gulf Coast from Brazosport, Texas to Tallahassee, Florida; rainfall exceeds 50 inches per year all along the route, in some places well over 60 inches per year. The Gulf moisture moves all the way from the Gulf to Canada, eventually dropping from the sky as rain.

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    $\begingroup$ Here is a wind rose from Greensboro, North Carolina, showing the typical wind direction over the course of the year. Indeed, the majority of the winds are from the southwest [city was chosen to get far enough away from the shore to take out much more local effects like seabreezes]. You can get a wind rose for any city at mesonet.agron.iastate.edu/sites/windrose.phtml to get a better idea of what wind is like climatologically in any location. Solid answer. $\endgroup$ Dec 17, 2022 at 9:04
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    $\begingroup$ @JeopardyTempest And here's Aitkin, MN from the same site. It experiences steady and strong winds from the NW (that happens from mid autumn to mid spring) and steady and strong winds from just a tad east of south (mid spring to mid autumn). From the west? Not so much, and definitely not strong. At 1200 feet of elevation, it's pretty much flat from the Arctic Ocean / Hudson Bay to Aitkin, and also from the Gulf Coast to Aitkin. $\endgroup$ Dec 17, 2022 at 21:11

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