California wildfire smoke targets B.C.
Friday, December 8, 2017, 6:57 PM - As parts of the Pacific Northwest contends with fog for the foreseeable future, is there another threat brewing from California?
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The California wildfires have seen a recent resurgence with six large fires spewing copious amounts of ash and smoke into the atmosphere.
Image courtesy of NASA Smoke plume seen from space, Dec. 8, 2017
The Santa Ana winds that ferociously descend from the mountainous regions of California have largely driven this firestorm—but those winds were primarily driven by topography (winds driven down narrow valleys). To track a smoke plume higher up in the atmosphere, there are a variety of tools at our disposal.
Let’s start to dissect this broadly, then look at more complex computer simulations. I’ll walk you through where we would expect the smoke to travel over the coming days.
We’ll slice the atmosphere in half and see where the mean flow is. An anomalous upper high pressure system over California and Nevada brings a lack of flow aloft directly over the source of the smoke. Weak westerly winds are steering the smoke and ash into the Pacific Ocean.
Large ridge of high pressure circulates air aloft towards Vancouver Island. Courtesy: WxBell
We would eventually expect the smoke to encounter a much stronger southwest flow aloft and begin a journey along the coast of the Pacific Northwest. One of the highest resolution computer models available suggests by Saturday and Sunday some high-level haze may be possible throughout coastal British Columbia. Coastal sections of Washington and Oregon won’t be immune from this possible haze as well.
Fine particulate matter from wildfire smoke modelled to push into Southern British Columbia, Canada.
A more technical way to view the possible path of the smoke is through a model that will track a parcel of air through the atmosphere. The parcel trajectory models can be very useful to track the spread of wildfire smoke across the continent. This model conveys the air aloft over the Pacific Northwest is originating from California.
Tracing the air particle back clearly shows the air originating from California, travelling up the Oregon and Washington Coast. Courtesy: NOAA
Smoke plume forecasts are imperfect, but signs are pointing towards the smoke plume migrating northward along the western fringes of the continental United States. Currently, we’re not expecting the smoke to mix to the surface in a widespread manner, which was the case for much of Summer 2017 for British Columbia and Washington. A haze may be observed across much of the region—unless of course you’re shrouded in fog.