California Imports Clouds and Smoke as Air Quality Improves Rapidly in Western Oregon and Washington

Air quality is improving rapidly west of the Cascades as easterly (eastward) winds are replaced by elevated southeast (south) winds. And the change in wind direction and increased humidity will allow rapid control of the Bolt Creek fire near 2nd Street.

These morning wildfire clouds and smoke were found all over our region…and you can thank California for much of it!

First, the air quality situation.

The latest AIRNOW map shows good air quality over the southwest coast of Washington (green) and moderate (yellow and orange) around Puget Sound. Poor air quality was found near the Canadian border, but that will blow north over the next few hours. Air quality is only slightly higher on the eastern slopes of the Washington Cascades….unfortunately, that could get worse the next day.

You can better understand trends in air quality (really small particle concentrations – PM2.5) from a Puget Sound Clean Air Authority plot. This shows particle concentrations in Seattle, Lake Forest Park (north of Seattle) and Bellevue. Peaked yesterday (especially at Lake Forest Park upwind of the Bolt Creek Fire), but has plummeted this morning by about 75%.

And there were some clouds overhead and even a few clouds this morning. To appreciate that, check out the latest regional visible satellite images. You can see mid-level clouds (actually white objects with shadows) and lots of low-lying clouds over the Pacific. The smoke (middle gray) is really clear in eastern WA and OR, as well as the falls in central Oregon.

The clouds, embedded in the southward current, can be watched as far back as Hurricane Kay off southern California. An infrared satellite image (below) shows this. No need for a tropical vacation… the tropics are upon you!

And a lot of the smoke in our area (mostly overhead) also comes from California (see NOAA’s Smoke HRRR forecast for this morning), with an increase from the Cedar Creek Fire in Oregon.

Meteorologically, the main factors controlling our improvement are the inland movement of the inland high pressure (ridge) and the approach of low pressure offshore. The weather map for about 5000 ft (850 hPa pressure) at 11 a.m. today (Sunday) shows the situation. The result is increased airflow in the lower atmosphere from the south and southwest.

As a result, the latest HRRR smoke forecast is for the smoke to move away from western Oregon and Washington at a low level (shown 8 p.m. tonight). If you live in the country of Puget Sound or Portland, you will breathe well tonight. But our gains will cause air quality to decline east of the Cascades. Sorry.

There are many lessons to be learned from this event. We can forecast potential hazards (dry, strong winter winds) with great skill. Portland Gas and Electric has strategically removed power lines, and at this point, I haven’t heard of any new fires there.

The fires in the west happen at exactly the same time as they usually do (late summer) and under typical circumstances… strong currents in winter. Clearly, the Bolt Creek fire was man-made, which implies that we need to send a clearer message about being extra careful during such (short) periods of threat. Some media has promoted a link between global warming, but I should note that this is not clear: the latest regional climate simulations show that strong winter flows in This time of year will weaken with global warming. Another important issue is the state of the burned forests…. but that analysis will wait for another blog.

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