Weatherwatch: fires in California and snow in Denver are linked events

Research shows human activity has raised the probability of hot, dry winds putting California increasingly at risk of wildfires

It’s been a dreadful couple of weeks for California. Raging wildfires have consumed more than 87,000 hectares (217,000 acres), an area larger than New York City. At least 41 people have died, 75,000 people have had to be evacuated and an estimated 5,700 homes and businesses have been destroyed.

The wine country to the north of San Francisco has been particularly hard hit, with entire towns having to be evacuated. By contrast, Denver, on the other side of the Rocky Mountain chain, received its first snowfall of the year. The co-incidental timing of these two very different weather events was far from a chance occurrence.

The strong high-pressure system that brought the snow over Colorado also fed the dry easterly winds, which rolled over the Rocky Mountains and funnelled through the canyons of the Sierra Nevada. As it tumbled downwards this dry air compressed and warmed, so becoming drier still. By the time the winds reached Sonoma county, California, they exceeded hurricane force gusting more than 77mph (125km/h). All that was needed was a spark and fire was inevitable.

Such winds are known as El Diablo (the devil) in northern California and Santa Ana in southern California, and, combined with a warmer, drier California, these winds are increasingly likely to be associated with wildfires in future.

Research published two years ago in the Proceedings of the National Academy of Sciences showed that human activities have increased the probability that dry years will coincide with warm years. And as these tinder-box conditions become increasingly common the golden state will need to be on high alert each time El Diablo and Santa Ana sweep in.


Contributor

Kate Ravilious

The GuardianTramp

Related Content

Article image
Weatherwatch: California's wildfires worsened by local wind conditions
Sundowner winds cause fires compared by firefighters to speeding freight trains

David Hambling

22, Aug, 2018 @8:30 PM

Article image
World weatherwatch: Mexico and Michigan suffer deluges as fires scorch Colorado
In US states, floods, huge sinkholes and wildfires, while along Mexico’s south-west coast Storm Carlotta packs a punch

Scott Duncan (MetDesk)

20, Jun, 2018 @8:30 PM

Article image
Wildfires' hidden energy revealed by lidar sensor
Weatherwatch Scientists using Doppler lidar to measure air currents and vortices created by uncontrolled blazes show why big fires spread more easily

David Hambling

22, Aug, 2017 @8:30 PM

Article image
World weatherwatch: Tornadoes, monsoons and snow
Tornadoes hit US as torrential rain causes floods in India and a cold front brings snow to South Africa

Brendan Jones (MetDesk)

04, Jul, 2018 @8:30 PM

Article image
World weatherwatch: Flooded Japan battered again by Typhoon Jongdari
Wildfires continue to rage in California, as drought in Australia shows no signs of abating

Brendan Jones (MetDesk)

01, Aug, 2018 @8:30 PM

Article image
World weatherwatch: avalanche risk strands tourists in Swiss resort
As two metres of snow fell in Switzerland, California was hit by heavy rain and mudslides that killed at least 17 people

Cassie Bell (MetDesk)

17, Jan, 2018 @9:30 PM

Article image
Weatherwatch: should TV forecasters talk about climate change?
Studies show even climate change deniers may be receptive to such news in bulletins

Kate Ravilious

25, Feb, 2019 @9:30 PM

Article image
Weatherwatch: California's clearer skies raise fire risk
Cloud cover is plummeting on the state’s south coast, leading to drier vegetation and greater threat of wildfire

Kate Ravilious

25, Jun, 2018 @8:30 PM

Article image
How warm seas powered two major hurricanes
Weatherwatch: Hurricanes Matthew and Nicole owed their deadly strength to exceptionally high temperatures in the Caribbean

Jeremy Plester

17, Oct, 2016 @8:30 PM

Article image
Weatherwatch: La Niña strikes out on its forceful voyage round the globe
Unusually cold patches of the Pacific ocean are again on the move, threatening to disrupt weather patterns worldwide

Jeremy Plester

16, Nov, 2017 @9:30 PM