Causes flying embers and falling trees. Maximum in October. From the Surface data plot for 17Z 22 OCT 00 Heavy rain in Texas, and water vapor is high near the Gulf of Mexico. Moist air being drawn north. Cold front through Baja California.
Winds are related pressure differences - high to low.
Air coming from region of higher elevation. Air comes from Reno, gets compressed because it descends. California is totally clear, and ground is dark. Relative humidity is lower. When clouds are brighter and whiter in picture, they are thicker and colder at the tops.