Strong Santa Ana Winds

Earlier this week, the southwestern region of the US experienced one of its worst wind storms in over a decade.  The winds that swept through the area were not a typical Santa Ana event.

The Santa Anas are robust easterly winds that blow dry air across southern California in the late fall.  It is formed by a large pressure difference that builds up between the inland Mojave Desert and the LA Basin. The steep pressure gradient between the two areas funnels air downhill through the canyons and passes of the San Gabriel and San Bernardino mountains toward the Pacific. Winds speeds generally reach somewhere between 40 and 60 mph.

This week’s event was unusual, because it followed a cold front and had a powerful northerly wind component with exceptionally strong gusts.  The NWS is reported to have measured wind gusts up to 140 mph along the Sierra Crest mountain ridge.  This fierce wind storm uprooted trees and knocked out power to over 300,000 people across the Los Angeles area.  Even LAX lost power and had to shut down briefly.

Another unusual aspect of this epic wind event was its wide reach across the region. Damage has been reported across the west from California to Colorado.  Some places in Utah experienced wind gusts over 100 mph and saw tractor-trailers flipped over like toys.

The tight pressure gradient that caused the storm has now weakened and the winds have subsided.  The forecast, however, is calling for blustery conditions to return to the southwest in the next few days.