Fires exploding across parts of southern California this week are do to the conditions in place that have been more than a year in the making.
November 29, 2016
During the winter of 2016-2017 much of California received enough precipitation to nearly wipe out long lasting drought conditions.
November 21, 2017
The extra rain and snow this last winter is a primary reason this year’s fire season has been on such a grand scale. Grow of vegetation across the state was accelerated with an abundance of water this past winter and spring and has since dried out becoming fuel for wildfires.
Summers are generally very dry across California and this past one was no exception, drying out an abundance of fuel for the wildfires we have seen. The overly dry summer was also hot and June-August 2017 was hottest summer on record in California.
The Santa Ana winds are the bellows that fan many fires in California every year. The devastating fires this week rapidly grew and intensified because of the warm and dry Santa Ana’s that originate from the higher elevations of the Great Basin.
These winds become warmer, drier and faster as they descend toward the coast of California. When high pressure sets up over Nevada and Utah the winds across southern California will blow from east to west and are known as Diablo’s and Santa Ana’s.
This winds are dried out a bit as they travel over the higher elevations across the Sierra Nevada mountains as moisture is condensed out into clouds, rain and snow. This now drier air is also relatively warmer, do to the heat released through condensation. As the winds move air into the much lower elevations in California the air is warmed adiabatically and accelerated. The moisture content doesn’t change much at this stage so as the temperatures increase the relative humidity will drop.
This gives us the strong, dry and warm winds that fans fires and is the case with the fires this week.