Alex Dodd, a meteorologist at National Weather Service in Eureka, California, confirmed that the convergence of current weather conditions and the record-setting wildfires have led to areas of Humboldt and Mendocino counties experiencing some of the worst air quality in North America.
Currently, one of the highest air quality index measurements in the region is Humboldt County’s Hoopa Valley reading 712, considered “Hazardous.” Dodd said Hoopa’s dramatic AQI is attributable to smoke from both the August Complex and Red Salmon Complex fires converging. Dodd explained offshore northwest winds have been unable to reach the Willow Creek & Hoopa regions’ inland valleys contributing to smoke and dangerous air quality.
Dodd explained that minimal winds over the last week have led to smoke accumulation within inland valleys. He said, “If you don’t get rid of that smoke, it gets locked in there. This results in a cooler surface layer while the warmer air stays aloft resulting in a stronger inversion and less potential for wind to clear out the smoke of the narrow, inland valleys.”
The Ukiah Valley currently has an AQI of 382, also considered “Hazardous.” Dodd said the topography of the Ukiah Valley, compared to regions like Hoopa, allows for more smoke to escape because of its size.
Dodd said that coastal regions are generally provided a reprieve from these sorts of air quality conditions. AirNow’s AQI measurements indicate Humboldt County’s Eureka currently has an AQI of 156, considered “Unhealthy.”
Dodd explained the most recent winds and pressures systems have led to wildfire smoked “mixing with the marine layer.”
Mendocino County’s coastline seems to be doing better in terms of AQI with Fort Bragg measuring at 52, considered “Moderate.”
Dodd said increased winds would help to clear the skies but warned, “[a]n increase in winds without also an increase in moisture will result in more fire activity and smoke production. If you’re upwind of the fires, you will experience fresher air.”
Dodd said that ultimately, the Emerald Triangle needs a rain front bringing a “push of moisture with some winds to calm the fire behavior and clear out the smoke. Until then, it’s hard to do both.”
Dodd did offer a glimmer of hope on the horizon. According to long-range modeling, Dodd says there are indications that the region could receive a pattern of cooler, moister weather around October 10-11, both clearing the skies and dampening the region’s wildfires.
The Mendocino County Air Quality Management District has prepared a Frequently Asked Questions site to address concerns associated with wildfire smoke, including the health risks associated with smoke, how to protect oneself from the smoke, how masks and respirators protect from smoke, and many more.