Santa Ana winds blowing hot and cold

[Lettucing Gutted]

The Santa Ana Northeasterly wind in California is often notorious for bringing super-natural heatwaves due to cold winds from The Great Basin, the Sierra Nevada and the Rocky Mountains experiencing adiabatic heating to pressure cooker heat levels as they head southwestward and downward to Los Angeles and the rest of Coastal California.

However according to this website http://www.topix.net/content/trb/387303151...327800901494139 the Santa Ana wind can also bring COLD weather to Coastal California.

I have a possible theory as to the factor that determines the temperature of the Santa Winds - Snow cover in the Rocky and Sierra Nevada Mountains and The Great Basin:-

-Less snow cover in The Great Basin and Mountains allows for weak cold high pressure air which easily becomes very hot due to adiabatic heating as they descend to Coastal California (Chinook type wind).

-More snow cover in The Great Basin and Mountains allows for extremely cold high pressure air to form but even with adiabatic heating it still brings cooler than average conditions to Coastal California (Mistral type wind).

I thought of snow cover as a possible theory because snow and glaze cool the air above it by reflective cooling (snow has a very high albedo as it reflects 90% of solar radiation falling on its white surface) and radiational cooling (snow and ice lose heat rapidly at night as they absorbed very little solar radiation during the day). The cooling effects of snow and ice generate shallow but strong high pressure areas close to surface. The cold high pressure air contrasts strongly with the relatively warmer and lower pressure air in Coastal California. The temperature and pressure gradients drive the Santa Ana winds from the mountains to Coastal California.

If anyone has any other theories as to Santa Ana temperature factors I will be happy to know.

Edited December 15, 2006 by Craig Evans