A thick column of smoke from the large wildfires in Alberta has spread to the Pacific Northwest.
The view from the Seattle PanoCam, looking northwest around 7 a.m. this morning, clearly shows the southern edge of the smoke cloud.
And satellite imagery visible at the same time shows a huge cloud of smoke extending southward over Washington State. You can also see low clouds over the Pacific Ocean, extending inland into southwestern Washington.
As the smoke moved in, visibility around Seattle was reduced and Cascades was now shrouded in haze.
Fortunately, surface air quality in Washington is fine, as illustrated by the latest fine particle values from the PurpleAir network (see below, green is good air quality). But near the wildfires in Alberta and their southwest, air quality conditions are dire and very unhealthy (purple).
Why is our air quality good, with a lot of smoke in the vicinity?
Because the smoke above does not mix to the ground!
To demonstrate this, below are graphs of ceilometer data from a unit in Marysville, WA deployed by the Puget Sound Clean Air Agency. Ceiling meters shoot a laser beam vertically and can measure the amount of smoke overhead.
Time is on the x-axis and increases to the right. You can see dark areas at altitudes between 2500 and 4500 meters above the surface. That is the smoke. This level is high enough that it is unlikely that it will be mixed down near sea level.
A classic situation. Distant wildfires produce smoke that can travel overhead but is too high to mix with the surface as the ground warms and the layers of the atmosphere below convection (moving up and down due to surface temperature) ).
So why are we capturing the smoke scene in Alberta? Because the lower atmosphere wind is moderate!
Here are winds at about 5000 ft (850 hPa pressure). Winds from the north over Alberta and east BC, become northeasterly winds (from NE) over Washington State. Perfect for moving Alberta’s smoke into the Northwest.
Why smoke now?
There’s been a lot of talk about the state of smoke, with some suggesting that global warming is the cause.
To understand the situation, consider that late spring is NOT an unusual time for large wildfires in northern Alberta. For example, there are the Fort McMurray wildfires of May 1, 2016 and the Flat Top fires of May 11-15, 2011. And there are many other examples that I could cite of major fires in the United States. Alberta in the spring.
Importantly, the fires were set by the hot/dry conditions in the AREA combined with unusually high pressure in Canada this spring.
Let me prove this to you. Here is the difference from normal altitude (like pressure) at 500 hPa pressure (about 5500 meters above sea level from 15 Mar to 15 May. Do you see yellow to red color? in southern Canada? That’s higher than normal altitude and pressure, resulting in a warm/dry condition.
Pulley/high pressure burned out. Also note that the anomalous pattern in the upper deck is associated with depressions (lower-than-normal pressure) on the West Coast, giving us a wet/cool pattern–especially in California).
Thus, wet conditions along the West Coast and dry/warm conditions in Canada can be traced back to the SAME anomalous superior pattern.
There is no indication that this waveform is caused by human-caused global warming. In fact, the peer-reviewed scientific literature has dampened such suggestions.
Could global warming have caused a few degrees of warming? You bet. But that represents a very small contribution to the situation.
___________________
Interested in a free lecture at UW on How will we prevent fossil fuels from causing global warming by Professor Myles Allen of the University of Oxford? It will take place at 7pm on May 25 at UW’s Kane Hall, and you can get more information and sign up below. Professor Allen is a very good speaker and is very famous all over the world; Talk will probably fill up quickly, so book early if you want to go.
