Canadian Smoke Coming to the Northwest

Although there are very few wildfires in Washington, Oregon, California, and southern British Columbia, there are significant fires in the Canadian boreal forests of northern British Columbia and Alberta.

And that smoke will push in aloft over Washington State tomorrow and Tuesday.

Below is a map of current Canadian wildfires. The big red dots show current, large active fires.

The problem for the Pacific Northwest is that an upper-level ridge of high pressure will develop offshore, with a trough inland, resulting in strong northern winds providing a fast conduit for smoke from the Canadian northern forest.

500-hPa map (around 18,000 ft) for Monday at 5 AM

The NOAA HRRR-Smoke model provides skillful forecasts of wildfire smoke.  Let me show you what it predicts.

Monday morning at 9 AM moderate smoke has entered Washington State aloft

One day later, denser smoke will push in aloft over our region.  The skies will lose the stark blue color of the past days.

Most smoke from distant sources generally stays aloft, but if the plume is low enough, some smoke can be mixed to the surface during warm days.  

Here is a vertical cross-section of smoke for 11 PM Monday.  Most remain aloft at that time.

But the strong heating on Tuesday (where temperatures will rise into the mid-80s) will mix some of it down to the surface (see a cross-section at 5 PM Tuesday).

Surface air quality ALWAYS declines on July 4th from all the fireworks.  This year the miasma will be "enhanced" by smoke from British Columbia.

The good news is that the upper-level flow will change (more westerly) by Thursday and will sweep the smoke away from our region.

As will discuss in a future blog, the latest forecasts keep our temperatures moderate, winds low, and the potential for wildfires modest.

Addition:   Here is the visible satellite image at 6:41 AM Monday, clearly showing the Canadian smoke moving southward into Washington State:

The Northwest is Now Smoke-Free. Let's Keep it That Way.

 Take a deep breath.

A visible satellite image this morning (July 1), shows no evidence of smoke anywhere over the Pacific Northwest.

This clean air situation is confirmed by air quality observations provided by the EPA AirNow network (below).  Green indicates excellent air quality,

There is only one small fire burning right now in the Northwest:  the Roza Creek Fire (about 700 acres) between Yakima and Ellensburg.   This fire, burning mainly in grass, is now 75% contained and probably started by human error.  Strong downslope winds during the afternoon and evening have sustained it, but such winds should weaken in two days.

 The July 4th Threat

 Grasses and small vegetation are now dry enough to burn in eastern Washington, with afternoon/evening winds along and east of the eastern Cascade slopes adding to the threat. 

 There is now a red flag warning out for much of eastern Washington (see below).  That indicates the acute potential for wildfire.

All that is needed is an ignition source, such as fireworks.  A plot of historical Northwest fires by date (below) shows a HUGE peak on July 4th.  The number one day of the year.  

And the supply of fireworks contributes to fires during the subsequent weeks as well.  Wildfires can also be started by errant barbecues, campfires, and shooting practice.

So please be careful on July 4th.   

Because of substantial precipitation in 2022 and early 2023, the grasses east of the Cascade crest are particularly bountiful.  

We are starting the three-month northwest fire season with below-normal fire numbers, and with little lightning expected during the next week, virtually all fire starts will be human-caused and thus avoidable.

The Warm Up

Conditions should be warm, but not extreme, this week.  In western Washington, temperatures will rise into the mid to upper 80s by mid-week, with temperatures rising to near 100F in the Tri-Cities (see predictions below).  Interestingly, the extended forecasts are suggesting a return to the persistent pattern of spring, with a trough over California.   

This pattern could bring below-normal temperatures to California and the return of thunderstorms to the Northwest.

More on that in a future blog.