South Winds funnel through southern california mountains Click to scroll

A Large area of Low pressure set up west of the California coastline over the weekend producing a moderate, sustained southerly flow. But those moderate winds were forced to squeeze through the North-South oriented valleys and when a gas or fluid is pushed through a constriction it speeds up and that is exactly what we saw.
The NAM 3KM Forecast Model clearly showed the contrast between wind speeds in the valleys and surrounding areas. The red indicates winds reaching into the 30s.
Anemometers in the Death Valley recorded speeds peaking in the low 30s which made it tough to keep a firm foot.

This has been a major shift in the weather pattern for the West. Much of the winter has seen an area of High pressure lingering along the Coast and consequently California has not seen much rainfall. But now it appears the pattern has shifted and Low pressure appears to be lingering.