A blocking weather pattern has encompassed much of the nation throughout the summer. A persistent area of high pressure and large-scale, high-amplitude ridging over the western half of the country has resulted in hot temperatures and extremely low atmospheric moisture content. These are the conditions necessary for the development of wildfires.
Last week, NOAA’s Geostationary Operational Environment Satellite (GOES-East; formerly known as the GOES-16/GOES-R series) captured the impressive smoke plumes generated by the wildfires in the western United States and Canada.
The above satellite image captured some incredible atmospheric phenomena. The smoke from the wildfires is evident by the brownish-like particulates, while clouds associated with a middle latitude low pressure system are seen over the northern and central Great Plains. Furthermore, the high altitude transport of the smoke plume was ingested into the low pressure system, revealing the classic dry slot often seen with mid-latitude lows.
Analyzing the Smoke Plume Sources
In the southern portion of the nation, dust originating from the Sahara Desert in Africa can be seen (while it appears to be smoke, the particulate matter is different and can be distinguished through various channels with the GOES-East imagery). As the sun reached its highest point during the day on August 23rd, resulting in peak refraction of atmospheric particulate matter (such as water vapor, dust, smoke), the imagery was visually astounding.
Smoke from the wildfires is clearly seen at various levels in the atmosphere (such as the middle levels as it is ingested into a mid-latitude cyclone in the northern Great Plains), to jet stream level across central and southern Canada, and into portions of the southern U.S. after a cold front moved through the region. The smoke had a direct impact on the development of convective clouds in the southern region of the nation, as fair weather cumulus struggled to deepen and therefore remained shallow as the smoke hindered maximum heating at the surface.
The “shelf life” of smoke particulate matter from wildfires can last for days, especially if it lofts its way into the middle or upper-levels of the atmosphere and into the jet stream. If smoke particles are ingested into an entrance region of the jet stream, the smoke can be transported for hundreds and even thousands of miles. This can be viewed in the satellite imagery above.
To put the high altitude transport of wildfire smoke in perspective, here are some satellite images that were captured by GOES-East a couple of days after August 23rd.
Barring a detailed discussion of atmospheric dispersion, if you have looked up at the sky over the past several days and have asked yourself: “Why is the sky a milky color?”, it is due to the high altitude transport and dispersion of wildfire smoke. Notice how the smoke layer thickens a bit more in the upper levels of the atmosphere over the Ohio River Valley and portions of the northeastern U.S. This is due to the smoke being transported downstream, or to the east, by the upper level winds.
Although wildfire events were high volume during the past several weeks across the western U.S., the spread of additional wildfires appears low at this time. Official fire weather forecast products from the NOAA Storm Prediction Center can be found here.