What Sort Of Weather Condition Designing Produces Lots Of Smoke Inwards Puget Sound?

Even amongst all the verbalise almost fume hither inwards Puget Sound, petty existent enquiry has clarified the weather condition patterns associated amongst our smoky days.

OK....let's address this deficiency!

I will produce this yesteryear using a technique called compositing--- finding a serial of times of big, recent fume events in addition to so averaging weather condition maps for these times.  Common features should reinforce themselves, showing us the essential circulation patterns accompanying smoke.

The times I volition composite are the most smoky times during the yesteryear 3 years:

8/21/2018    1500 UTC , 8/15/2018   0300 UTC , 8/4/2017 1200 UTC

8/9/2017 1200 UTC, 9/7/2017 0000 UTC, 8/23/2015 2100 UTC

First, let's composite a illustration mid-level parameter-- 500 hPa heights (think of it similar pressure level roughly 18,000 ft)--see below.

Mama mia, in that location is quite a signal!  Big ridge of high pressure level over the West Coast, amongst troughs (low pressure level or height) over the eastern Pacific in addition to the eastern U.S.

If yous actually desire to come across the wave-like anomalous upper circulation, hither is the same map amongst the hateful values for the menstruum taken out (these are called anomalies from climatology).

Amazing. When nosotros possess got smoky periods, anomalous high pressure level is constitute over southeastern BC. Such high pressure level is associated amongst warm, sinking air aloft. In contrast, the eastern United States of America has a cool trough when nosotros larn smoky.

What almost at the surface? There nosotros tend to larn lower heights (or pressure) over western Washington due to the warm air aloft (see below). We telephone telephone that characteristic a thermal trough. In such a pattern, the normal eastward Pacific high pressure level surface area is pushed offshore, other high pressure level builds inland, in addition to the onshore current of railroad train clean body of body of water air is interrupted. In fact, amongst high pressure level inland, nosotros tend to larn offshore (easterly flow), which pushes inland fume over Puget Sound.

This pattern--high pressure level aloft centered over southeastern BC, thermal trough over western WA, lack of onshore flow, in addition to small-scale offshore flow-- is real adept for pushing  fume over western WA. And it brings warm temperatures in addition to dry out conditions across the region...good for fires.
   

But the enquiry yous are scream for is whether this blueprint has choke to a greater extent than frequent inwards fourth dimension in addition to whether global warming could hold upward the cause.  H5N1 real adept question.

To assist respond your question, I possess got plotted for over many years the values of the 500 hPa heights (think pressure level at roughly 18,000 ft) over just the portion associated amongst our rut waves-- the surface area centered on SE British Columbia-- for July in addition to August (see below).  Higher heights (or pressure) is associated amongst our smokiest periods. (see below).  This figures does non furnish insight into what happened during tiptop of the smoke, only the full general surroundings of the surrounding months.

No wonder this was the large twelvemonth for smoke!  This twelvemonth had the highest heights/pressures aloft since the belatedly 1940s.  Heights look to possess got risen over the yesteryear decades, which is expected equally the portion (and the planet) possess got tardily warmed.  Warming causes air to expand, which increases the heights aloft.  This year's spike upward seem anomalous in addition to unprecedented, in addition to this is why is would hold upward unexpected to possess got a repeat side yesteryear side year.

 Why produce I say that?  Because I possess got done extensive enquiry (with graduate Matt Brewer) on just this issue.   Heights aloft are controlled yesteryear the hateful conditions (which are tardily rising amongst the warming earth) in addition to transient high pressure level areas, similar the i over southeast BC that was associated amongst the smoke.    Our enquiry (based on yesteryear trends in addition to climate models for the side yesteryear side century) suggests that transient high pressure level areas should hold upward attenuated nether global warming--which would locomote against the fires in addition to smoke.   On the other hand, global warming would  warm temperatures in addition to so assist trim back relative humidities,  which so encourage burn in addition to smoke.

So the bottom trouble is this.  The anomalous patterns (big ridge of high pressure level along our coast), which was the proximate displace of our warmth/dry conditions/fires/smoke this year, were in all probability non the trial of global warming.  Thus, they are in all probability due to the chaotic, random nature of the atmosphere.   The little background warming nosotros possess got experienced inwards our portion (1-2F) helped the fires/smoke slightly only weren't dominant factors.

But yesteryear the destination of the century, equally global warming actually hits, the potential for Northwest fires volition substantially increase, everything else beingness equal.