National Weather Service United States Department of Commerce

Arctic Front Brings Winter Weather and Colder Temperatures to the Eastern U.S.

A series of cold fronts will bring heavy lake effect snow to the northern Great Lakes. The fronts will merge over the Ohio Valley and bring colder temperatures east of the Mississippi River later today into the end of the week. Additionally, wintry weather will develop over the Ohio Valley, Appalachians, and Northeast as rain switches over to snow tonight into Thursday morning. 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.