June 10, 2021

Wildfire Outlook for the Pacific Northwest

During the past few days, I have received several calls from the media asking about the potential for wildfires this summer around the region. 

They ask:  will this be a major wildfire year with lots of smoke?

There is particular concern about wildfires because of our dry spring.

So let me try to answer this question, using the latest weather forecasts and new insights gained from research on the connection between weather and wildfires over our region.   My analysis will be more nuanced than being provided by some.

Northwest Wildfires Can Be Divided into Three Main Types

There is no such thing as ONE wildfire forecast for the region because the origins of fires differ so radically around the Northwest.  That is why general statements or projections about regional fires are inevitably simplistic and wrong.

As shown below, one can identify three main wildfire areas in the Northwest.  

First, there are the forested regions west of the Cascade crest (indicated by the red box below)

 Major fires in this area only occur with VERY strong easterly (from the east flow) during late summer, generally at the end of August or early September.  Fires are rare on the west side, but when they do occur they can be large and catastrophic because there is so much fuel.  

The fires last summer in western Oregon (September 8-13) were good examples of such fires.  The Tillamook Burns in the Oregon coastal range of the early to mid 20th century are another.  

Dry/warm conditions enhance west side fire potential but are not required for such fires.


Then there are the grassland and range fires, such as those of the Columbia Basin of eastern Washington (cyan box).  These fires are ignited by humans and lightning and tend to move very fast when winds are strong.  The fuels (grass, small bushes) are dry enough to burn by June every summer and thus the existence of fires is not very climate-sensitive.

Finally, there are the lower to mid-slope fires of the regional terrain east of the Cascade crest (indicated by yellow boxes). This region has Ponderosa pines, western red cedar, and white oaks on the lower slopes, transitioning to Grand and Douglas firs at mid-slope. Lack of snowpack and dry/warm conditions during spring and summer contribute to drying the "fuels" and strong winds have been associated with a number of the major fires.  Ignitions come from human origins and lightning.

So now the predictions for this summer.

West-side Wildfires:  Low Probability

West-side fires require unusually strong easterly winds.  Such winds are very dry and their strength can help start fires (e.g., from downed powerlines) and foster their rapid growth and spread.  The easterly winds during the wildfires of last September were the strongest ever observed in western Oregon during late summer.

The chances of getting such strong winds this year are low from a climatological perspective.  But there is more.   The probability of strong easterly winds during late summer/early fall is enhanced during La Nina years, such as last year.(during La Nina years the sea surface temperature of the central tropical Pacific is more than .5C below normal). Fortunately, La Nina has weakened and we are now experiencing Neutral conditions during which strong easterly flow over western WA and Oregon is LESS LIKELY than during La Nina years.  

Why are La Nina years good for strong late summer easterly flow events?  Because there is a tendency to get upper-level ridging in the eastern Pacific, with strong troughs moving down its eastern side.  Such troughs bring strong winds.

Another major positive is the unusually wet period forecast over the western side of the region during the next week.  You don't see situations that wet in June very often.


Furthermore, the unusually bountiful late-season snowpack will lead to moistened upper elevations of the westside forests  (see below).

Although not impossible, the probability of a west-side fire like last year should be quite low.

Grass/Range Fires in the Columbia Basin:  Lower Probability Than Normal

By this time each year, the grass/rangeland of eastern Washington is dry enough to burn.    But there are two reasons why one should be hopeful this year.

First, because of the below-normal precipitation this spring the grass is quite sparse, so sparse that ranchers are complaining about lacking forage for their herds.


Another region for optimism is about wind.  The large/fast-moving grass/rangeland fires in eastern Washington last Septembler were initiated by and spread by unusually strong winds.  For the same reasons as noted above (end of La Nina), the likelihood of such strong winds (from the north, northeast, and east) are less this year than last.

Lower to Middle Slopes East of the Cascade Crest

This is the area of greatest wildfire threat this year.  Looking at the departure of precipitation from normal, much of eastern Washington has been drier than normal by 0-4 inches, with particular concerns along the eastern slopes of the southern Washington and Oregon Cascades because of the dense, poorly managed dryland forests that are found there.


The sparse grasses this year are positive, but what fuels are available are drier than normal (the Northwest  Coordinating Center suggests we are about 3 weeks ahead of schedule).

A favorable factor is the substantial amount of rain expected over the weekend.  Eastern Washington and Oregon could get as much as .5 inches....which is a lot this time of year for that region...and temperatures will be relatively cool.  This kind of rainfall will help suppress the chance of wildfires along the eastern slopes for several weeks.


The bottom line is that there are competing factors regarding eastern slope fires, so that the chance of such fires during the next few months is probably near normal.  

We all must be careful not to initiate fires in that environment.  With poor forest management and fire suppression, we have created a dangerously flammable situation on the eastern slopes of the Cascades and in the Okanagan, a situation worsened by frequent human fire ignitions.

25 comments:

  1. While the further north sections of our region may be protected, this doesn't take into account the severe drought produced by such a dry spring in much of Oregon and California. While winds are necessary, I am of the understanding this it being so dry will cause just as many fires as wind would. If I am wrong that is fair, but I still think there is cause for concern in S Oregon and California for certain. Up here is hard to say, I will agree.

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    1. You need to re-read Cliff's post, which analyzes both forest and grass fires. The dynamics are different, as he explains.

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  2. Your analysis is a breath of fresh air, so to speak. Today's weather folk are often only able to repeat "what the models are telling us" without any analysis or discussion at all. Thanks again, Cliff!

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  3. +I have to disagree with your comments about the upcoming rain in June being a factor that will reduce the threat of wildfires later this summer. Along the Cascade east slopes, even if we get a fair amount of rain out of this storm, if the rest of June is dry and warm and the warm, dry weather continues into July and August, and dry lightning storms are a factor this summer, which they were not last summer, we could be in for a serious fire season. You mention that we may not get the strong northeast winds that we got last summer, but many of our large range fires in Eastern Washington came with strong westerly type winds, especially along the lower Cascade east slopes, and these are quite common. I do agree that the dry spring has resulted in less grassy fuel so fire may not be as intense. Also, I believe a good rain from this storm in western Washington and Oregon would not be a factor by late summer and fall if another good east wind event occurs since it does not take long for strong east winds to dry out the fuels. Both the 1933 Tillamook fire and the 1902 Yacolt fire occurred in years when the previous months were not especially dry. In sum, if we get a pretty good rain out of this next storm, it will help for the near future but not for the whole summer unless the weather continues cool and damp well into summer.

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    1. Um, go read some history. 1902 was an abnormally dry year, and strong easterlies were present. The same conditions were present in 2017, when a teenaged arsonist started what became a 45,000-acre fire that started in the same place.

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    2. The nearest station to the Yacolt fire area with a long term record is Vancouver,WA.
      It is likely representative of much of the fire area. In 1902, Vancouver precip. from Janunary thru August totaled 26.17". The long term average for that period was 21.05. From June thru August 1902, Vancouver recorded 3.00". Normal was 3.12" so near normal summer rainfall for 1902 but above normal for the year up to September. There were many drier summers than 1902 at Vancouver both before and after. Likely the main cause was an extended period of dry east winds prior to the fire with possibly a period of rainless days in the weeks or days just prior to the fire, but it was likely the strong east winds that were most responsible.
      Jim Holcomb

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  4. As you’ve stated in past years, SWE maps in June are of marginal significance because the snow’s on its way out anyway. I don’t agree with that, but understood your point.

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  5. Good luck trying to log our way out of fire risk along the east slope of the Cascades. Or for that matter, anywhere else. Open up the forest canopy and expect the understory to dry out that much earlier in the season. Punch in a spiderweb of logging roads and expect an immediate increase in the most prolific firebug of all (us). And to suggest there will be funding for crews to go in every five years to beat back the flammable brush that fills in the thinned gaps. Across hundreds of thousands of acres, with no generated revenue to speak of?

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    1. Please detail your forest management background. And while you're at it, please tell us why almost all of the big burns happen in unmanaged gov't forests. Within 25 miles of where I live, 100,000 acres of gov't forests have burned within the past decade. We are also surrounded by regularly-logged private forests, which have not burned.

      I'm sure you're a "progressive," probably from Seattle, so you know it all. So kindly share that knowledge, along with your background.

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    2. Big burns in gov't forests partly were, as Cliff said earlier, because the USFS suppressed all fires for nearly a century and allowed the understory brush build-up. The other reason is that whatever the cause, summers are getting longer, drier, and perhaps in some cases, windier. But there were bad fire years early in the 20th century, so the last few years were not as unusual as people think. Like it or not (for me, mostly not).

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    3. Every single thing you wrote is false. But you are a Seattle "progressive" -- same one as the unfortunate soul who writes (or wrote) for "The Stranger?" So by all means, keep making up lies. It's what the "progressives" do. You know NOTHING, but you will never be caught admitting it. Arrogance and ignorance are your offense and your defense; Lenin taught you well.

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    4. This comment has been removed by the author.

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    5. So what was your field of study?  I have been a student of science all my life and that is what I do.  The USFS, after a century or more of experience, has decided that fire, for the most part, should be suppressed only when it endangers towns so that understory growth is naturally controlled.  For thousands of years before Man arrived, there was no one to "manage" the forests.  Mark Twain, when he first visited this area around the turn of the last century, mentioned that the smoke prevented him from seeing the mountains.

      You are saying that summers are not getting warmer and drier? Look at the mountain glaciers.  The proof is there and I have seen it myself.  They are shrinking, and you don't have to be a rocket scientist (figuratively) to see it.  More proof?  The mountain pine beetle plague is traced to milder winters.

      I don't make stuff up, like our last president did.  I repeat what I heard from others, or I make my own observations.  Science doesn't lie.

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    6. I always love being lectured by a Seattle "progressive" who knows nothing. Iron Law, baby.

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  6. Excellent overview with lots of good data to back it up. Thanks for the education.

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  7. Yes, it is true the media like to keep the public running scared so they behave. They mention high fire danger, but when fire danger is low, they are largely silent.

    But it is true that the West Coast has a fire-prone climate regime. Trees high in pitch (pines, firs) combined with dry summers. On the other hand, fires are rare on the East coast: High humidity, frequent summer rains, and mostly tree species low in pitch content.

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  8. A significant component of the tragic wildfires in California was the stock marketization of public utilities such as PG&E and Southern California Edision. The boards of these traded entities cut back on necessary line maintenance which led to short circuits throughout their networks when NE winds were severe. They even resorted to rolling blackouts during severe wind events to reduce their media exposure. Even now they are calculating their risk and I predict they will blame the drought conditions as they reduce maintenance even further. I am hoping that the wetter conditions here have helped to keep the infra structure in better repair.

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    1. Ah yes, the Seattle "progressive" omits any mention of the stupidity, negligence, and outright dishonesty from the "environmentalists" who convinced the politicians of CA, OR, and WA to abandon time-tested forest management practices.

      You were warned at the time but there's the Iron Law: "You can always tell a 'progressive,' but you can never tell a 'progressive' single thing. They think they know it all."

      So rather than put the blame where it belongs -- on yourselves -- you will invent baseless excuses. Anything but self-examination. Gosh, that might force you to admit facts, and that is NOT something "progressives" will be caught dead doing. No way.

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    2. What nonsense is this? Progressives have a monopoly on conviction of their own infallibility, and the denial of fact? Not sure what country you live in, but it is not the States...

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    3. I'm an American. Unlike your kind, I don't hate this country's guts to the point that I would legalize crime in Seattle as long as the criminal is black.

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    4. "...who convinced the politicians of CA, OR, and WA to abandon time-tested forest management practices..."

      No- they are still learning how forests work. The "time-tested" practice of suppressing all fires was (and is) part of the problem. Man can't get used to the fact that the dryland forests evolved with fire. Don't like it? Go live in New England where fire is rare. Or in a true desert where there is nothing to burn.

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    5. Oh, come on. "progressives" didn't start the Paradise fire. The power company did by placing the lines in a dry, windy place without proper safeguards. More "forest management" might or might not have mitigated it.

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    6. Iron Law: "You can always tell a Seattle 'progressive,' but you can never tell a Seattle 'progressive' a single thing. It thinks it knows everything."

      By the way, abolish the Seattle fire department. Good ideas start at home. LOL

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    7. These days, it seems, when it comes to politics no one can tell anyone else anything, whatever side they are on.

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  9. "...particular concerns along the eastern slopes of the southern Washington and Oregon Cascades because of the dense, poorly managed dryland forests that are found there."

    Spot on. The MSM here in The People's Republic of Portland never mention this, even after it was proven that corruption and mismanagement of the forests here was a primary contributing factor in the statewide massive burn downs back in September. Granted, it was not the only factor, but it was one of the main ones.

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