California is in the midst of perhaps the most challenging fire year in its history, with yet another dangerous set of weather conditions developing in a state that endured unprecedented heat and explosive blazes over the weekend. Source: The Washington Post
More than 2.2 million acres have burned so far in 2020, surpassing 2018 for the most acres burned annually in the modern record. Three of the state’s four largest wildfires have occurred in the past three weeks — all exceeding 300,000 acres and not yet fully contained. The Creek Fire in Sierra National Forest, where rescues of trapped hikers and campers are still underway, has ballooned to 143,929 acres in two days, with 0% containment.
But the wildfire threat is not limited to California.
On Monday, blazes broke out amid strong winds and dry air in Washington state. Some of the blazes spread dozens of miles in a single day.
In western Oregon, wildfires grew in number and severity throughout the day Tuesday, pouring smoke plumes out to sea and turning skies in some areas an unsettling orange hue. One fire reportedly destroyed an estimated 80 to 100 structures Monday night in Blue River, located east of Eugene along the McKenzie River in the Willamette National Forest.
Wildfire smoke mixed with airborne dust to create hazardous driving conditions and dangerously poor air quality in the state, with widespread road closures in central and eastern Washington as well. Hazardous air quality as a result of wildfire smoke has spread across the West.
On Tuesday, red-flag warnings for dangerous fire weather stretched along the entire West Coast from the US border with Mexico to Canada, including much of California and Nevada, western Oregon and Washington, along with western Arizona and southern Utah.
Strong winds are buffeting areas in and around Seattle and Portland with wildfire concerns in both areas. In some places, winds have been strong enough to knock out power.
The National Weather Service’s Storm Prediction Center wrote that the fire danger was particularly severe in parts of western Oregon and far southwestern Washington state, where it described “extremely critical” conditions. There, the combination of wind gusts over 60 mph, low humidity, high temperatures and a parched land surface “all suggest continued potential for rapidly moving fire fronts and extreme fire behavior,” the center wrote.
The acreage burned in California, while astounding, does not tell the whole story. Fires have been burning in unusual ways this summer, with fire behaviour that eludes firefighters’ control. That has allowed them to grow so big, so quickly, without much wind to push them along. Fuelled by record-setting temperatures, up to 120 degrees even near the coast, they have spawned towering columns of smoke and ash, forming their own thunderstorms and even fire tornadoes.
But the heart of the fire season is still ahead: Fast-spreading blazes are most common in autumn, when fierce “offshore” winds blow from inland areas toward the coast.
Those winds arrived this week, unusually early, on the heels of a record-shattering heat wave. Red-flag warnings are in place for much of Northern and Southern California, as well as the Sierra Nevada mountains and foothills, as critical fire weather migrates from north to south. The winds threaten to push existing fires into communities, particularly those in the Bay Area and in Los Angeles, San Bernardino and San Diego counties, which are burning near populated areas.
These winds will transport extremely dry air, with humidity measured in the single digits. This combined with the desiccated vegetation following the heat wave will create rarely encountered wildfire risks.
The California utility Pacific Gas and Electric, whose power lines sparked the state’s deadliest wildfire on record, which wiped out the town of Paradise in 2018, has begun to implement pre-emptive power cuts that could affect 22 counties across the state.
In the Los Angeles area, the biggest immediate fire weather concern is related to the Bobcat Fire, burning in the San Gabriel Mountains just north of Azusa. Forecasters and firefighters are concerned the Santa Ana winds will cause the fire to burn down canyons to nearby foothill communities Tuesday and Wednesday.
The US Forest Service has taken the unusual step of closing several national forests in California because of the extreme fire danger, which puts vast swaths of the state off limits to campers, hikers and other users. Dry, gusty offshore winds are expected in the San Francisco Bay area Tuesday, with a red-flag warning through Wednesday morning.
