Smoke Increasing
One thing that has spared the western Washington lowlands so far is some cleaner air coming down from the Strait of Georgia between British Columbia and Vancouver Island. This has been scouring out some of the smoke along and west of I-5 from around Everett northward to Bellingham. These winds are expected to persist into Wednesday and may ultimately prevent worse smoke impacts in these areas.
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| DNR Pano Cam from Orcas Island looking toward Bellingham. |
Further inland and to the south, AQI levels on smoke monitors and sensors along the west slopes of the Cascades and in the southern Puget Sound continue to creep upward as smoke travels down the rivers and highways towards foothill communities like Darrington, Sultan, North Bend, and Enumclaw.
Further south, smoke continues to increase along I-5, especially around the Portland/Vancouver metro as smoke moves toward the west through the Columbia River Gorge.
In eastern Washington, widespread Unhealthy conditions are expected to continue. Locally Very Unhealthy to even Hazardous conditions are likely in close proximity to the fires. The only sliver of eastern Washington that has seen improved air quality over the last 48 hours is from Oroville to Northport.
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| Air Quality Alert map |
Air Quality Alerts (AQAs) will continue in central and eastern Washington until further notice. In western Washington, AQAs have been expanded to include Kitsap, King, Pierce, Snohomish, Thurston, Mason, Grays Harbor, and the eastern portions of Whatcom and Skagit counties. AQAs in Clark, Cowlitz, Lewis, Skamania, and Wahkiakum counties are currently set to expire at 5:00 p.m. Wednesday, all others expire at 5:00 p.m. Thursday.
What Can I Do?
If you are reading this, you're off to a great start! One of the best things you can do during smoke events is to keep tabs on your local air quality. Smoke can fluctuate quite a bit throughout the day. If you can, wait for the air quality to improve before going outside. For those living near active fires, check the forecast from the Air Resource Advisor assigned to the fire.
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| Information from NWS Seattle |
It's also important to keep your indoor air clean. Avoid activities that kick up dust or consider using the oven instead of the stove. If you have air conditioning, make sure it's set to recirculate so you don't pull in smoky outdoor air. Run a portable air cleaner if you have one.
You may also consider purchasing some supplies to help you out. A NIOSH-approved N95 mask can be great if you need to go outside while it's smoky. If you don't have a portable air cleaner, consider making a DIY Box Fan Filter.
Not only is the smoke building, but so is the heat. Stay hydrated, keep curtains and window shades closed, and avoid using the oven or stove during the hottest parts of the day. Put some ice packs or damp cloths in the freezer to keep yourself cool. For more information, visit the Department of Health's Hot Weather Safety Guidance.
If you are unable to stay cool at home, visit 211 Washington to find a cooling center near you. If a cooling center is not on the 211 map, contact your local health jurisdiction.
When Will the Smoke Clear?
This is always a tough question to answer while the smoke is still building, but we will start to see a gradual shift in the winds on Wednesday that will at least start the clearing process in western Washington. Without a strong push of marine air, it's going to take time. This is why most AQAs have been extended until Thursday evening.
East of the Cascades, smoke is going to be much more stubborn until stronger westerly winds arrive. Some improvement may take place along the east slopes of the Cascades Thursday afternoon and evening, but the stronger winds that really scour out the smoke won't arrive until Friday. One they do, areas east-northeast of the fires will once again be in the path of the smoke.
Fire Weather
Speaking of strong winds, we do have some fire weather concerns worth mentioning. In the western Columbia Gorge, a Red Flag Warning is in effect until 8:00 p.m. Wednesday for locally gusty winds out of the east combined with low relative humidity.
Looking ahead, the winds that will help scour the smoke in eastern Washington will also contribute to critical fire weather conditions Friday and Saturday. While not as strong as this past Saturday, sustained winds around 15-20mph with gusts between 35-45mph will overlap with very low relative humidity values. In addition to growth on existing fires, we may once again be tracking smoke from new, fast-moving fires.
What is the threshold for issuing in AQA? "Moderate" on the AirNow AQI scale, or USG?
ReplyDeleteAir Quality Alerts are generally issued for current or forecasted smoke impacts. Generally that is when air quality is currently or forecasted to be at least Unhealthy for Sensitive Groups for a sustained amount of time. The exact thresholds for air quality alerts may vary among Local Clean Air Agencies.
DeleteI'm so tired of inaccurate predictions year after year. Every time, the smoke lasts at least a few days longer than predicted. Why can't the models account for this? Heavy smoke always lingers longer than we are told.
ReplyDeleteThanks for your comment. Without knowing which models you are referring to or what location, it's challenging to address specifics. There are many assumptions and uncertainties that go into smoke models, including fire emissions and plume rise assumptions. Some models use detailed historical fuel loading maps, assumptions of acres burned per satellite detect, or assumptions of the amount of fuel consumed (and heat released) to drive the model. Other models use heat release detected from satellite to drive the fire emissions and plume rise parameters. Another uncertainty is how far back you acquire fire locations. There are also uncertainties and assumptions associated with fire behavior, initial conditions, boundary conditions, and carryover smoke. In short, models have inherent uncertainty which is why we try to discuss the range of outcomes on the blog. Air Quality Alerts also account for lingering smoke and gradual clearing. Air Quality Alerts in Central and Eastern Washington are in effect until further notice, and Air Quality Alerts in Western Washington are in place until tomorrow evening. Air Quality Alerts are also routinely evaluated to take into account the latest air quality conditions and forecasts.
DeleteHello and thanks so much for this information/help. We use it all the time. I am interested, however, in why/how the same sensor (Purple) show so differently on this map versus the Purple map at the same time? It is sensor ID: 32489. See here . Best!
ReplyDeletePurple Air sensors overreport PM2.5 concentrations, so most other sites use a correction for their data. You can apply the US EPA conversion on the purple air map, by navigating to the upper left drop down menu. That same drop down menu has an option for averaging period. Selecting "1 hour" is comparable to what government agencies report.
DeleteThanks Farren. I was wondering about over-reporting with Purple as I have a Smoggie as well that, when pm2.5 levels increase, seems to diverge substantially lower than the Purple. I have changed the Purple map to show 1 hour instead of 10 minutes and still the Purple map differs from the one here. Is there documentation on the "correction" mechanism that other sites use? Best
ReplyDeleteI think you might be seeing the difference between "NowCast" shown on this blog and other sites, and the hourly values on Purple Air. Purple Air doesn't show NowCast on their site as far as I know. NowCast weights the last several hours, with the most recent hour carrying most weight. You can click on a monitor and navigate to more charts to see hourly concentrations, which may help reduce the difference in maps.
DeleteThanks once again Farren. I have found info on the EPA "correction" mechanism employed with Purple sensors. With this in place in my own computations, the results very closely match those shown here. I appreciate all the help. Best
ReplyDelete