Friday, August 30, 2019

This smoke season's anomalies explained, with a Labor day smoke forecast tacked on

Easy part first:

Western WA Labor day weekend smoke forecast
After a welcome dousing of rain yesterday and consistent on- shore flow this weekend, the fire risk will remain low. No major smoke impacts expected over the Labor day weekend so go ahead & enjoy the Good air, but please be diligent and prevent new fires. Too many reports of abandoned campfires, dragging chains and discarded cigarettes starting new fires.

Eastern WA smoke forecast
Two issues worth mentioning, although one of them may not amount to much:

  1. Some spotty smoke is present around Asotin County, likely from the Cow Fire in Oregon, and the area is likely to see intermittent Moderate air over the next few days. 
  2. All the smoke models are assuming that a few fires in the Okanogan- Wenatchee National Forest are actively pumping out smoke and they maybe right to some extent, but are likely overstating the magnitude. Haven't seen any measurable smoke impacts at Leavenworth, Chelan, the Methow Valley or Stehekin as yet and don't expect area air quality to degrade beyond Moderate on occasion.

Other than that, we're mostly expecting Good air provided there are no new fires. Warmer, dryer conditions are predicted to return mid week, reminding us that the fire season is not over yet.

WZUP with this wildfire smoke season?

Here's an animation showing how the worst air quality days in the last 2 wildfire seasons compared with this year. While 2019's worst day thus far wasn't even close to those of the previous two anomalously smoky years, it occurred so early in the season (May 31) and got us all worried about what might transpire. More so since the seasonal outlook available at that time called for a slightly warmer-than-normal and dryer-than-normal summer.
Thankfully, that smoky scenario hasn't played out this year. The chances of the smoke monster making a comeback are diminishing as the sun becomes more preoccupied with baking the southern hemisphere.

The # of wildfires burned by today in 2019 is lower than the low- smoke years of 2013 & 2016. How nice to be lagging behind!

Year-to-date
# of fires nationwide
2019 (1/1/19 - 8/29/19)
32,887
2018 (1/1/18 - 8/29/18)
43,448
2017 (1/1/17 - 8/29/17)
45,981
2016 (1/1/16 - 8/29/16)
39,997
2015 (1/1/15 - 8/29/15)
43,511
2014 (1/1/14 - 8/30/14)
38,454
2013 (1/1/13 - 8/30/13)
34,256
Data source: National Interagency Fire Center

Here are some of the main meteorological factors that mitigated the build-up of smoke that was released from the few fires that did burn. I've only considered the anomalous smoke years of 2017 & 2018 in one of the graphics below (#2. wind vector animation).
  1. Less frequent high pressure systems over us
    Here's a comparison of the height at which atmospheric pressure reaches 500mb (usually around 18K feet above), showing differences between 5 recent summers (excluding 2017 & 2018), and 2019. Data are June- July composites from global weather models that have been re-analyzed after the observational data became available. 2019 August data aren't yet available.
    The yellow over our region suggests that upper level pressure in past years were 10- 20m higher than what we saw in June- July this year. Not an insignificant difference. Include 2017 & 2018 and the difference jumps to about 35m.

    Higher pressure = lighter winds, warmer temperatures and dryer air. All the factors needed for conducive fire behavior and poor smoke dispersion happened less frequently this year.

    An aside: notice how areas to our north & the Arctic had higher pressure this year than the last few. We had several early season fires in northern Alberta & Alaska. In fact the May 31 2019 smoke shown in the air quality map animation above mostly originated from northern Alberta.
  2. Stronger upper level winds aimed at the Pacific Northwest

    Here's how the 700mb level (about 10K feet above) winds in recent summers compared with 2019. Notice how 2019 winds aimed at the Pacific NW are stronger than their 2012- 2018 counterparts. More active weather impacting our region = less chance for air to stagnate. 
  3. Cooler upper air temperatures

    And now, a 850mb level (4500 feet above) temperature difference plot. 2-3C warmer in other years than 2019. For a two month average, that's quite a difference. Cooler upper level air temps this year = less ground level warming & drying out.
Why the region's seasonal climatic variables behaved this way is beyond the scope of this blog. This season's fire behavior is compared & contrasted in a recent interview. The interested reader can compare ground- based observations of temperature and precipitation each year, against historical norms using the following NWS links.




Wednesday, August 28, 2019

Eh? Whats that smoke over the Puget Sound and Yakima?

Around 11AM yesterday the satellites started detecting a large cloud of smoke from a hotspot in the Wenatchee National Forest in Yakima county, just east of Highway 410. This was from a 300-acre prescribed burn authorized by DNR. Smoke was buoyant and lofted over the Cascades courtesy of strong east winds. Here's what the satellite picture looked like at 5PM yesterday.


The fire was smoldering this morning and a further 230 acres were authorized for burning at the same location today. A little bit of the smoke that drifted west appears to have mixed to the surface this morning, with several Puget Sound area monitors recording Moderate air for a few hours. The latest smoke models show this dissipating by afternoon today. However the residual smoke could exacerbate the potential for ozone (smog) formation in the east slopes of the King/ Pierce County Cascades today, so air quality due to the combination of fine particles and ozone is likely to stay in the Moderate to Unhealthy for Sensitive Groups through late this evening. On-shore airflow overnight is likely to restore Good air quality to most of western WA by Thursday.

Since smoke models assume that fires continue to emit all day & night, they're predicting that the Yakima valley will see some smoke impacts today & tomorrow. Given such assumptions, it is hard to determine the amounts of smoke that will actually reach populated areas. Needless to say some smoke is projected to drain into the valley so nearby communities should brace for compromised air over the next day or so.

Models are also showing that smoke from the Cow Fire in Oregon (see above) is likely to brush the far southeastern part of the state by Thursday evening into Friday as the wind shifts. Amount of smoke is unknown at this time.

All this bears watching. We will post an update and a long weekend outlook on Thursday.

Monday, August 26, 2019

Summer returns this week, but what about smoke?

At the time of writing, the state is almost entirely cloud free. What you dont see clearly in this short satellite animation is a very thin layer of Alaskan smoke that is drifting over western WA, likely contributing a little fine particle pollution to our ground level monitors. Some Puget Sound area monitors briefly showed Moderate air this morning.
Western WA forecast

The Canadian model shows this smoke mostly blowing offshore and staying away after today. Winds wont become dead calm today or tomorrow, so chances of lingering smoke are low. Barring new fires in the area, fine particle pollution levels are expected to remain Good, with perhaps a few splotches of Moderate through Wednesday. Ozone however, is another story. See below.

Eastern WA forecast
No major fires at present, neither is the area expected to be downwind of any fires through Wednesday. However there's a long list of small fires at any given time, and conditions are right for their growth this week. Expecting mostly Good air through Wednesday except near fires. The public is strongly encouraged to do their due diligence and exercise utmost caution to prevent the spread of fires.

Ozone
Conditions are right for ozone (smog) formation Tuesday & Wednesday on both sides of the Cascades. Problem spots are around Enumclaw and Yelm in western WA, and Kennewick in the east. Some periods of Moderate air should be expected. Ozonematters.com provides succinct information on proactive steps that can be taken to minimize ozone pollution.

However it must be mentioned that summer 2019 hasn't had many high ozone days. Here's a plot showing how Kennewick's ozone days and potential ozone days compared with past years. Potential ozone days (gray bars) are when the day's weather lined up with historical meteorological conditions under which elevated ozone levels were observed. It is clear that there were fewer days where weather was conducive for ozone this summer, even when the rest of the summer is taken in account.
Our next blog post will provide a smoke forecast for Labor Day weekend, and we will also explore some of the reasons why this summer has been a low smoke year thus far.

Wednesday, August 14, 2019

No Smoke on the Horizon

The Williams Flats fire activity is low, with some minimal creeping and smoldering.  Firefighters estimate that it should be completely contained by this Friday. 

The NWCC Morning Brief states that holdover fires continue to be discovered in Washington/Oregon but they are exhibiting low fire behavior with minimal spread potential. No new large fires have been reported and forecast fire danger is mostly low to moderate.  However, there is still potential for brush fires in southeastern Washington.  Expect continued Good air quality across most of the state for the foreseeable future, with some occasional Moderate blips in select locations.

The weather forecast for the next few days shows dry and normal temperatures, with some marine layer clouds expected in western Washington.  Moderate winds are expected through the Cascade gaps during the afternoons for the next few days.  Widespread cloudy skies are expected this weekend, with continued northwesterly flow off the coast pushing clouds over eastern Washington.  Don't expect much precipitation, but a few showers are possible on Friday and Saturday.

No images of smoke to share (that's a good thing), but the GOES-West imagery showed some interesting cloud structures travelling across WA/OR border this morning:


Thursday, August 8, 2019

Dicey smoke forecast for north-eastern quadrant of the state, mostly OK elsewhere

As explained in the earlier forecast, air quality in the Spokane area hovered around Unhealthy levels overnight, with some relief during the afternoons. Here's the satellite picture from Wednesday afternoon.

Smoke from the Williams Flats fire continues to be a problem around the far eastern part of the Colville reservation and Spokane County. The Devoe Creek fire close to Stehekin and the Eagle Bluff fire along the Okanogan River valley in British Columbia are also sending smoke into north central WA and the Columbia Basin.

Another day of high temperatures on tap for most of eastern WA but a rather turbulent transition period over the next 2 days makes forecasting tough. A front approaches tonight, increases winds and thunderstorm risks, swirls the smoke around and then dumps some rain on the area. Smoke models are not showing huge improvements in air quality before Saturday evening and the wildcard is smoke from possible new fires.

It's not all bleak. Higher humidities, lower temperatures and some rain will help curtail fire spread, not to mention provide some relief from the searing heat. Here's what the UW-WRF model shows for 72-hr total precipitation totals by Sunday morning. Hitting all the right places, it seems:

So while its hard to pinpoint specific places and times for smoke impacts, the best advice we can offer folks in the northeastern quadrant of the state is to prepare for Unhealthy air close to fires, and Moderate to Unhealthy for Sensitive Groups elsewhere. 


Good news for western WA: a strong marine push has ventilated out most of western WA and clouds are likely to hang around today (sorry summer aficionados 😧), alleviating smoke concerns for a while... provided potential thunderstorms today & tomorrow dont spark off new fires.


In other news
  • The Dept of Ecology and the US Forest Service have installed temporary air quality monitors in Cle Elum and Stehekin respectively, to track smoke impacts there. Data can be viewed on the map above. 
  • Tri Cities ozone is likely to stay just below the Unhealthy for Sensitive Groups threshold today, as a wind-shift in the afternoon puts the brakes on ozone-formation. Timing of the winds are key; a delay of a few hours could push the area into USG air.

Wednesday, August 7, 2019


Spokane area smoke:
In the Spokane area, downwind of the Williams Flats fire on the Colville Reservation, smoke levels have been hovering in the Unhealthy-for-Sensitive-Groups to Unhealthy-for-everyone range for the couple of days.  Currently there is heavier smoke in the Green Bluff - Mount Spokane area.  For a lot of folks - mainly the elderly, children and anyone with heart or lung disease, this poses a health concern. Over 40% of the population falls into the Sensitive Groups category.  So even if you don’t mind the smoke, understand a lot of people are likely being affected. The longer air quality stays bad like this, the more people can be bothered. When the air quality is unhealthy for sensitive groups, people with heart or lung disease, children, people over 65, and pregnant women should limit outdoor exertion, and when the air quality gets worse than that, everyone should limit outdoor exertion. Anyone experiencing symptoms of heart or lung disease from smoke exposure should contact their health care provider. Visit WDOH’s Smoke from Fires for more on steps to reduce your exposure to smoke.