National Weather Service United States Department of Commerce

Severe Weather in the Central Plains; Heavy Rainfall in the Tennessee Valley; Critical Fire Weather in the West

Scattered severe storms capable of large to very large hail, severe wind gusts, and a few tornadoes will be possible across the central Plains this evening. Heavy to excessive rainfall may bring a flooding threat from the Great Lakes to the Mid-South through tonight. Hot, dry and windy conditions will continue to bring a critical fire weather threat from the Southwest into the Great Basin. Read More >

Wave clouds (or gravity waves): These form when stable air moves over a raised land feature, such as hills or mountains, and is forced upward. Gravity then causes the air to fall back down, and it begins to oscillate, creating that ripple effect. 

 

 

This visible satellite image was taken at 400 pm PDT 9 Sep 2000. The cloud lines oriented north to south are wave clouds. They are the result of west-to-east wind flowing over the Cascade mountains of Washington and the Rocky Mountains of Montana and Alberta.