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Treebeard's Stumper
31 October 2003

Devil Winds

Halloween is fun. Chaparral wildfires driven by Santa Ana winds are scary. We've been spared this time, so far. Our local fires were controlled because the winds didn't happen, though this smoky fire weather is scary enough. Why don't we get these dangerous Santa Ana (or santana?) winds in Santa Barbara? We do have local sundowner winds, so what's the difference? Heat rises, but all these devil winds get hotter and dryer as they blow down the canyons. How does this work? The real stumper is how should we live in a natural landscape that is adapted to burn.

We got an inch of rain on Halloween day. A lot of people had to change their Halloween plans. The big fires are still out of control, and the weather will change again. But I feel much better about our wildfire situation at home.

This beautiful image of Southern California wildfires (red) and smoke plumes was captured on October 26, 2003 by the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument on the Terra satellite. The NASA Earth Observatory Natural Hazards site has links to more images of the fires this week. The MODIS Image Gallery has impressive hi-res images to download.

I added a few markers. I live in the mountains behind Santa Barbara (#1). Santa Ana winds blow from the high Mojave Desert (#2) on the edge of the Great Basin. That striking wedge on the western edge of the desert is formed by the San Andreas and Garlock earthquake faults. It's like an arrow pointing to the ocean, which is about how Santa Ana winds move. The top fires (#3) are the Piru and Simi Fires. The next arc of fires (#4) are the Grand Prix (west) and Old (east) Fires on both sides of Cajon Pass. It's interesting that there are no fires near San Gorgonio Pass (#5). The Paradise and Cedar Fires (#6) are covering San Diego with thick smoke.

This satellite image really shows the effects of Santa Ana winds blowing offshore from east-to-west across Southern California. You can also see that we missed the worse of it near Santa Barbara, though it was smoky enough. (Click or visit Treebeard's Photos for a larger image.) Our local winds stayed onshore, which brought the smoke around in an eddy.

Why don't we get Santa Ana winds in Santa Barbara? Heat rises, so why do these hot and dry down-slope winds exist at all? For bonus stumpers, where else in the world do these devil winds occur, and what are they called? What cultural links in books and movies and song can you find?

Smoky sunrise, fire weather.
(San Marcos Pass, 28 October 2003)

Answer


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Copyright © 2003 by Marc Kummel / mkummel@rain.org