National Weather Service United States Department of Commerce

Heavy Rain in the Southern U.S.; Active Weather Continues in Alaska

A storm system will bring heavy rainfall, thunderstorms, and flooding threats to portions of the Southern Plains today, the Lower Mississippi Valley Saturday, and the Southeast into the Mid-Atlantic on Sunday. Another Bering system will impact the Alaskan West Coast and Central Interior through the weekend bringing moderate to heavy snow, high winds, and/or some blizzard conditions. 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.