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Thomas Fire

Unit Information

Los Padres National Forest
U.S. Forest Service
Goleta, CA 93117

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Persistent Santa Ana Wind Event Challenges Thomas Firefighters

Thomas Fire Wildfire
News – 12/15/2017

Persistent Santa Ana Wind Event Challenges Thomas Firefighters

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The Thomas fire has experienced a long duration Santa Ana wind event, which began on December 4th, and has contributed to rapid growth and extreme fire behavior. Santa Ana winds originate from high-pressure air masses over the Great Basin and upper Mojave Desert. These cool dry air masses sweep across the deserts of eastern California through the mountain passes and canyons to the Pacific Ocean. Three things happen under these conditions: It gets warmer, winds get faster, and humidity plummets. The Thomas Fire has experienced winds exceeding 70 miles per hour, temperatures in the mid 80’s and humidity below 10 percent.

Furthermore, the topography that makes the Los Padres National Forest a unique landscape also makes it a dangerous place to fight fires. The mountain ranges in the forest run east-west, funneling the winds down the steep canyons and setting up dangerous conditions to fight fire. Firefighters must always be on constant alert for shifting winds which threaten their safety.

Santa Ana Wind events usually last 1-2 days and then subside and while it’s unusual to have such an extended duration, it is not the longest Santa Ana Wind event recorded. In 1951, a strong Santa Ana Wind event lasted 24 days, beginning on December 9 and lasting into January.