The Franklin Fire has rapidly grown to more than 1,000 hectares as of Tuesday, fuelled by extreme weather conditions. Discovered late Monday evening, the fire rapidly quickly grew out of control under a red flag warning––an indication of extreme fire danger across California.
The last red flag warning in the region was issued in November when a massive wildfire tore through Ventura County. What makes this setup so dangerous?
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(RAMMB/CIRA/NOAA)
Read ahead to find out the science behind the setup.
Weather setup
Santa Ana winds
These particular winds are famous for catalyzing extreme fire behaviour. The powerful, dry winds originate inland and are driven towards the coast of California by high-pressure systems.
As the air descends through mountain passes and valleys, it compresses, warms, and loses even more moisture. This process not only dries out vegetation, but also accelerates fire spread with gusts often reaching more than 100 km/h.
Extreme dryness
The combination of exceptionally low relative humidity, and bone-dry vegetation has created horrendous fire-weather conditions.
When these factors are paired with Santa Ana winds, the recipe can be catastrophic.
The terrain amplifier
Look no farther than the mountains of California. The rugged terrain plays a crucial role in increasing the winds and fire danger.
Below, we’ve exaggerated the region’s topography to highlight the mountains and valleys.
Santa Monica Mountains and Malibu Canyon
The Santa Monica Mountains, located just north of Malibu, Calif., act as a natural wind funnel. The Malibu Canyon channels the winds, accelerating them as they approach the coast––further intensifying the pressure on the fire zone.
The climate context
Southern California is transitioning out of its dry season, but the region has been particularly parched.
Six-month precipitation anomalies highlight that this typically dry climate has been even drier than usual.
The previous winter provided ample moisture to Southern California to stave off drought conditions, but this prolonged dry spell will have to be monitored in the coming months.
Looking ahead
Some relief is on the horizon.
Winds are forecast to ease into Wednesday, giving firefighters a critical window to gain control. There is some indication of light shower activity moving across Southern California later this week, but the rainfall will be insufficient to extinguish the Franklin Fire.
Hundreds of personnel are fighting the ongoing #FranklinFire in Malibu.
Fire season is not just a season in California — it’s year-round — and that’s why we pre-position resources, engines, aircraft, and equipment to respond in real-time. pic.twitter.com/mKmCJ7nHBi
— Governor Newsom (@CAgovernor) December 10, 2024
Header image credit: @applegreentech via Storyful.