I was taking my daily check of AWC and saw several reports of Mod-Sev turbulence and just Straight up Severe turbulence in socal. They were all from small aircraft. The interesting thing is that the METARs are showing very calm winds and even Windy.com is showing light winds. I read both reports and one of the extreme turbulence ones said that the winds were 20kts and another one said that the winds were 3kts. Regardless even 20kts over mountains isnt enough wind to cause severe let alone extreme turbulence even in a Cessna 172.
Heres the link to the website so you can see it for yourself https://aviationweather.gov/