Last night at around 9:30 p.m. I stepped outside of our Meadowmont cabin to observe the sky. I noticed the pines swaying away and a roar in the sky. Very freaky. Then the noise moved down the canyon towards Murphys and slowly disappeared. The trees stopped moving. All was over in a matter of minutes. I must have stepped out as this thing was moving over Arnold. I’m guessing that the cold air up the canyon was descending down hwy 4 into the valley. How often does this happen? Is this common in the winter in the mountains on clear nights?