Deadly Wildfires Blaze in Northern and Southern California

California, once again, is ablaze with wildfires.

As of Tuesday, three major wildfires – defined as 100 acres or more – are burning in the Golden State.  Collectively, according to National Interagency Fire Center (NIFC), they have burned more than 200,000 acres and claimed the lives of 44 people. In terms of property damage, close to 8,000 homes and business have been destroyed and at least another 50,000 are at risk.

Sweeping through the wooded northern California town of Paradise, the death toll from the Camp Fire currently stands at 42. That makes it the deadliest wildfire in the state’s history. It surpasses the Griffith Park Fire, which killed 29 people in 1933. Sadly, with 200 people listed as missing, the death toll from this fire is expected to climb even higher in the coming days. It is currently only 30% contained.

At the southern end of the state, the Woolsey and Hill Fires have forced massive evacuations. Raging west of Los Angeles near Malibu and only 30% contained, the Woolsey Fire has charred more than 93,000 acres and destroyed more than 400 structures. The Hill Fire, currently at 85% containment, has scorched upwards of 4,500 acres.

Air quality issues are another concern with these wildfires. Well outside of the burn areas, many people are wearing masks to protect themselves from the smoke and ash carried in the wind.

These huge fires are largely the result of climate whiplash. California has distinct wet and dry seasons, but they have been extreme recently. After years of drought, the state saw increased precipitation over the past two winters that spurred explosive plant growth. Then during this past summer, which was unusually dry, all that vegetation turned to tinder.

Making matters worse, the region’s seasonal winds, known as the Diablo Winds in the north and the Santa Ana Winds in the south, kicked into high gear. Flowing from east to west, downslope from the mountains toward the coast, these winds warm from compression and dry out vegetation even further. They also fan the flames of any fire already burning and can cause it to spread very quickly.

To date, according to NIFC, 1.5 million acres in California have been burned by wildfires in 2018. That number, however, is expected to go up as these fires continue to spread.

The Camp Fire in Northern California seen from space. Credit: NASA

How the Santa Ana Winds Help Wildfires Spread

The Santa Ana winds are notorious for exacerbating wildfires in southern California.

These strong winds blow warm, dry air across the region at different times of the year, but mainly occur in the late autumn. They form when a large pressure difference builds up between the Great Basin – a desert that covers most of Nevada and parts of Utah – and the coastal region around Los Angeles. This pressure gradient funnels air downhill and through the passes of the San Gabriel and San Bernardino mountains toward the Pacific. Squeezing through these narrow canyons, the wind is forced to speed up. The Santa Anas, according to the NWS, can easily exceed 40 mph.

Originating in the high desert, the air starts off cool and dry. But as it travels downslope, the air compresses and warms. In fact, it warms about 5°F for every 1000 feet it descends. This dries out the region’s vegetation, leaving it susceptible to any type of spark. The fast-moving winds then fan the flames of any wildfires that ignite.

The Santa Ana winds are named for Santa Ana Canyon in Orange County, CA.

Credit: NOAA/NWS