Monday, September 25, 2023

Residential wood smoke from home-heating on the rise

It's gotten cold out there!  Autumn is finally here and with that comes cooler weather and the need to heat homes.  Residential wood smoke from home-heating should be expected, especially at night and in the mornings when woodstoves and other wood-burning devices are regularly used.  Temperature inversions and light winds can cause smoke to stagnate, especially in valley communities.  This blog is intended to focus on wildfire smoke, but forecasts will be issued by Local Clean Air Agencies on their own sites and on AirNow.  As the season progresses, the National Weather Service may issue Air Stagnation Advisories and clean air agencies may initiate air quality burn-bans posted on their web pages, though we usually don't see those until November. 

Wednesday, September 20, 2023

Favorable Wildfire Smoke Outlook; Prescribed Fire Season Starting!

Recent rainfall and cooler temperatures limit smoke production on active wildfires

It certainly appears that wildfire season in Washington is winding down! A series of two cold fronts swept across the state on Monday and Tuesday, with the latter bringing cooler temperatures and rainfall to most areas of the state. As the westerly winds picked up ahead of the cold front on Tuesday, some individuals reported smelling smoke in the Seattle/Everett/Mt. Vernon corridor. This was likely a result of the still-smoldering fires in the Olympic Mountains, but air quality remained Good at all locations! 

Speaking of the fires in the Olympics, the Delabarre Fire has burned 3,658 acres as of September 19th, narrowly edging out the 2018 Maple Fire (3,273 acres) and the 2015 Paradise Fire (2,791 acres) to become the largest fire in the Olympic Mountains since the Great Forks Fire of 1951. Below is a map of all fire perimeters in the Olympic Mountains from 1951-2023, with the Delabarre Fire highlighted. Fortunately, the recent rainfall and cooler temperatures should limit any further growth of the incidents on the Olympic Peninsula. 

The other major smoke producer in Washington over the past month has been the Airplane Lake Fire, which has consistently funneled smoke into the Leavenworth/Wenatchee Valley. This fire also saw rain yesterday, though less than the Olympics. It is possible that with warmer weather on Thursday and Friday the Airplane Lake Fire may perk up a bit, but winds will be out of the east, providing the aforementioned areas with relief from the smoke. Some elevated smoke will likely be transported toward the Puget Sound, but I do not expect enough burning activity to produce any impacts above occasional MODERATE readings. 

Looking ahead to the weekend and early next week, I expect our first widespread heavy rain event to impact all areas along and west of the Cascades beginning Saturday and continuing through the first several days of next week. A true Washington Autumn classic, winds will be gusty and several periods of rain are expected. Below is the total precipitation forecast from NOAA's Weather Prediction Center through Wednesday morning, and you best believe this will tamp out any wildfire smoke concerns for the foreseeable future! Currently, the heaviest rainfall is expected on Monday and Tuesday. 

As wildfire season winds down, prescribed fire season picks up. Prescribed fires also produce smoke concerns, but the smoke is much shorter lived and burns are regulated to minimize air quality impacts across the state. The goal of prescribed fires is to promote a healthier, more wildfire resistant landscape, and are a very important tool in reducing wildfire danger to communities across Washington. If you live near US Forest Service or Washington DNR managed lands, follow your local USFS or DNR offices on social media to stay up to date on any planned burns in your area! 

Friday, September 15, 2023

Outlook: good air quality and localized smoke impacts

 The majority of the state continues to experience good air quality and low fire danger. A very clear satellite image from this morning--only the smoke plumes from the Airplane Lake Fire and agricultural burning in SE WA are visible, as well as smoke in Oregon):

The Airplane Lake Fire continues to cause intermittent smoke impacts around the Lake Wenatchee area and into the Wenatchee Valley, impacting the communities of Leavenworth, Cashmere, and Wenatchee. These intermittent smoke impacts will continue until the next significant precipitation event. There is potential for light smoke impacts today in East Snohomish County, but winds from the west this weekend will push any smoke east of the Cascades.

Across the rest of the state, fires in the Cowlitz Complex comprise almost 700 acres and are partially contained. Smoke from these fires is not expected to impact nearby communities. The Sourdough Fire continues to intermittently impact areas close to the fire in the Ross Lake National Recreation Area. There are also a few fires currently burning in the Olympics that were ignited two weeks ago by lightning strikes. Smoke from these fires (including the Eagle Point and Low Divide Fires) may intermittently impact Port Angeles and higher-elevation areas around Port Angeles. 

Weekend outlook: warm and dry conditions are forecasted for the weekend, but we're not expecting any significant new fire activity. Increased smoke from any local fires and prescribed burning may cause localized moderate air quality levels. Forecasted high winds across Central and Eastern Washington along with the dry conditions can lead to rapid fire spread; please continue to recreate responsibly.


Taking a look back at our air quality this wildfire season, below is a plot of observed daily air quality levels for each day in each county in the state where there is an air quality monitor. Each row corresponds to the daily average at the most impacted monitor observed in each county on a given day. The major events we saw this wildfire season are highlighted--smoke from the Alberta fires in May, smoke from the Cascades and Southern BC fires in August as well as local fires in Spokane, and smoke from fireworks on the 4th of July. 

And how does this season compare to previous years? If we look at a timeseries of PM2.5 concentrations averaged across the state during wildfire seasons over the past 10 years, this year we saw smoke impacts in August, which is pretty typical. In previous years, easterly wind events have contributed to large smoke events in September and October. While it's only mid-September, that seems increasingly unlikely to occur this year, thanks to the recent cool temperatures and precipitation in the region and the low number of active fires in the Cascades.

Friday, September 8, 2023

Good air quality and low fire danger

Despite good air quality in most of the state, the Airplane Lake fire still has active hot-spots and is producing smoke that's been impacting residents around Lake Wenatchee.  Intermittent moderate smoke is also affecting the nearby communities of Entiat and Cashmere.  The Airplane Lake fire has only grown 200 acres over the past few days, but the fire is uncontained and will continue to produce smoke until the next wetting rains occur, which are not expected anytime soon.  

A wind shift is expected tonight, and moderate smoke from the Airplane Lake fire is expected to impact mountain towns in Snohomish County (such as Darrington) over the weekend.  That shouldn't last long though, as westerly winds are expected to pick back up on Sunday afternoon.

The Sourdough fire near the Ross Lake National Recreation Area is partly contained and has not grown much at all, prompting officials to reopen some trails and camps in the area.  Smoke from the fire has been minimal and intermittent, with no large hot-spots detected recently.

Other fires of note in Washington are in the Cowlitz Complex, with 700 acres burned across several fires.  Despite partial containment, there is still moderate fire behavior at the Snagtooth, Spencer Quartz, and Grassy Mountain fires.  No significant smoke has been detected in the area so far, but sensors are sparse in the region.

Fire danger remains too low for much risk of new significant fires in the coming days. The majority of our wildfire season has passed, and we don't expect any big flare-ups.   Since air quality and fire weather are not a concern, agricultural burning in the Columbia Basin and Idaho has begun.  Residents near agricultural communities from Yakima to Whitman county will likely see intermittent moderate smoke from agricultural burning through the month.

Smoke from the Airplane Lake Fire (image courtesy of