In the United States, strong, easterly winds, often locally referred to as canyon winds, blowing out of the mouths of the canyons of the Wasatch Mountains onto the plains of Utah. They are produced by a strong large-scale west to east pressure gradient and are best developed when there is a large high over Wyoming or a vigorous low to the west or southwest in Utah or Arizona. In extreme cases they can exceed hurricane force. The strong winds are mainly limited to the canyons, especially in winter, but in some circumstances extend beyond them onto the plain.