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Storm Impacting the Northwest U.S.; Fire Weather Conditions in Southern California; Severe Weather in the South

A Pacific storm is bringing areas of low elevation rain, moderate to heavy mountain snow, and high winds to the Northwest. Strong Santa Ana winds and very dry conditions are producing elevated to critical fire weather conditions in southern California. Isolated strong to severe thunderstorms are possible through early Wednesday morning across parts of northeast Texas into western Tennessee. Read More >

Mountain Wave Activity Over the Southern Rockies

When stable air flows over the rugged terrain in and around New Mexico, mesoscale circulations known as mountain waves can develop. An example is shown in the visible satellite image below. When the wind speed is sufficiently strong and perpendicular, or nearly-perpendicular to mountain ranges, waves develop over and downstream of the barriers. If enough moisture is present in the air, clouds will develop in the portion of the wave with upward vertical motions. While the wind speeds may be 30 kts or greater, the waves remain nearly stationary for periods up to several hours. While these waves are visually appealing, both in satellite imagery and from the ground as lenticular clouds, these waves are often associated with turbulence and therefore, are considered to be an aviation hazard.

A study on criteria associated with mountain waves over New Mexico was completed in 2004, and is available in pdf format.

animation of satellite imagery depicting mountain waves
 

Visible imagery from 18 October 2004 illustrating an extensive area of mountain waves over the Four Corners region.