Freak Wind Storm Wallops Western States

The wind storm is finally subsiding in the West, but it has left a widespread trail of destruction and frazzled nerves in its wake. Fueled by an epic difference in air pressure between the Pacific Northwest — where Seattle set an all-time record for its highest air pressure reading — and the Southwest, where a strong area of low pressure set up, high winds funneled over, through, and down the backside of mountains and mountain passes.

According to The Weather Channel, winds topped 100 mph in Utah, California, and Colorado, and came close to the century mark in Nevada and New Mexico. In the Los Angeles metro area, wind gusts of 40 to 70 mph were common.

NOAA computer model visualization of wind speeds and direction during the high wind event. The lightest blue to white colors represent the strongest winds — up to 80 mph. The flow vectors show the direction the winds are blowing. 

At the summit of Mammoth Mountain in California, sustained winds of 140 mph — equivalent to a Category Four hurricane — were reported, along with gusts to at least 150 mph, according to the National Weather Service. Update: reports that an even stronger wind gust of 167 mph was recorded at Henniger Flats, Calif. If verified, that would be truly astounding.

In Pasadena, California, 200 buildings were damaged by the storm, and trees were toppled along with power lines (and even gas stations) throughout the West. At the peak of the event, high wind warnings and advisories were in effect from California to Wyoming, and hundreds of thousands of people were without power.

These high winds were unusual even for Southern California, which is used to strong offshore wind events known as “Santa Ana winds” that typically occur during the fall. Normally Santa Ana winds usher in hot and dry air. However, in this case, the winds drove colder air into the region, and were far stronger than normal. According to the Los Angeles Times, the winds were also extremely variable, which added to their destructive potential:

In some places, winds suddenly shifted from 10 mph or 20 mph to more than 80 mph. The shift made trees as well as roofs and power lines vulnerable.

“Everything lined up perfectly,” said Bill Patzert, a climatologist for Jet Propulsion Laboratory in La Cañada-Flintridge.

Historically, Santa Ana winds have been associated with major wildfire outbreaks, but in this case there were only scattered fires reported. One study that examined how global warming may alter Santa Ana wind events found that they may shift later in the season, from fall to winter, which would change some of the wildfire dynamics in the region.