Hope mixes with uncertainty when it comes to forecasting this week’s wildfire smoke.
Some cooler weather tinged with rain over the next two days
would likely make fire crews smile if the package didn’t include some stiff
wind gusts.
A low pressure system will swing by from the North Pacific
pushing a cold front tonight and tomorrow that will cut across Washington and
displace hot dry air from a high pressure system centered over the Great Basin.
But, later in the week, after this low passes, the weak high pressure system
will spread back over Washington.
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| Smoke under clouds: This webcam picture from a resort near Winthrop shows today's north central Washington smoke haze, under an overcast of regular clouds. |
Some light rain will help throughout the state, with relief especially welcome along the east slopes of the Cascades and northeastern counties. Rain will also pass over British Columbia, which may help with the fires whose smoke sank onto much of Washington Friday and Saturday.
The other side of this coin is wind. Gusts could reach 40
miles per hour, which will likely fan fires and speed their spread. The wind
direction will shift from west to north. That could push a lot of the BC
smoke our way. It’s unclear how much smoke will be generated and mixed down to
the surface. Our forecasting models disagree so far, but we hope to bring that
into better focus over the next two days.
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We’ve issued an Air Quality Alert for Okanogan, Ferry,
Douglas, Stevens, Pend Oreille, Chelan, Kittitas, and Yakima counties through
10 a.m. Wednesday due to smoke from local fires and the uncertain amount of BC
smoke that will move south tomorrow.
Western Washington will have plenty of fresh coastal air for
at least another day. There will be smoke overhead starting Tuesday, with
potential smoke impacts at high elevations on Wednesday.
Be sure to open the “local smoke outlooks” tab on this blog for specific warnings and information about Washington fires.
Will the "potential high elevation smoke" for Wednesday impact the Olympics?
ReplyDeleteEarly on Wednesday morning there is potential for smoke to impact the Olympics starting at about 3000 feet. Starting around 11 AM, the winds shift to north westerly and marine air should clean this out. This is based on forecast northerly winds bringing smoke down from British Columbia. That said, we don't know what will happen with BC fires, the terrain is complex, causing unpredictable, microscale wind patterns, and lastly there will also be dilution with clean marine air. I do not expect air quality to be worse than moderate or USG at most hiking elevations.
DeleteWhen you say "potential smoke impacts at high elevations on Wednesday" what is high elevation? 3000 feet, 6000 feet, 10k feet?
ReplyDeleteHi Alex, great question. One of the main models suggests that we could see smoke as low as 3000 ft by Wed morning. Here is the prediction for 7am Wed: https://rapidrefresh.noaa.gov/hrrr/HRRRsmoke/for_web/hrrr_ncep_smoke_jet/2021081618/htxs/htxssmoke_seaA_f44.png
DeleteThe image is a cross-section looking northward from SeaTac (see inset on the top-right). The mountains to the left are the Olympics and to the right, the Cascades. The y-axis on the left is height and the smoke plume bottoms out around 1km or 3000 ft.
Thank you Graeme, this cross section model is an awesomely interesting image. How do I find updated snapshots of the cross section model? I'm on this page: https://rapidrefresh.noaa.gov/hrrr/HRRRsmoke/Welcome.cgi?dsKey=hrrr_ncep_smoke_jet&domain=t1&run_time=18+Aug+2021+-+15Z and I can get a bunch of the maps but even when I put "XSection" under the domain, I'm not getting links for the Cross Section SEA images. Do you know what I could be doing wrong? Thank you so much! You all are wonderfully helpful.
DeleteAlex, some of those images are only generated during the 0Z, 6Z, 12Z & 18Z model runs, so you'll have to pick the nearest hour. If you check right now (just before noon on 8/18), selecting "18 Aug 2021 12Z" as the Date will work.
DeleteRanil, thank you so much! That worked - you all are the best.
DeleteIt looks like there is more rain over the weekend, do you think that will clear things up again or are we going to get trapped in smoke by Bellingham from whatever this weather pattern is that is bringing down the smoke from canada.
ReplyDeleteCurrent long-term models suggest the Bellingham area could see a light amount of smoke this weekend, but my guess is that the ground-level impacts will be minimal given the windy weather.
DeleteThanks for keeping it real. Smoke forecasting is so challenging! Also- appreciate the reminder to check out the “local smoke outlooks”. Hoping to head to Union Gap this weekend for the Pioneer Power tractor show. Will check back here on Thursday.
ReplyDelete