As the Oregon Gulch fire burned, along with many other fires in the vicinity, smoke filled the skies in northern California and portions of southern Oregon Friday afternoon. If the fires continue to burn, the smoke we are seeing will persist for the next few days. There is no major change to the current weather pattern, which is what’s needed to shift the smoke out of the area.
The smoke Friday diminished air quality across the region. In the Rogue Valley, as well as Siskiyou County and northern California, air quality was rated in the moderate category. That means the smoke in the air poses a moderate risk to a small number of sensitive groups, such as those with asthma or other breathing conditions. It is, in general, safe to be outside for the time being. The high temperatures over the past few days have helped lift the smoke through the morning, but now with the large amount of smoke present, it begins to drift back down towards the surface by the late afternoon. Through the overnight hours, more dense particles of smoke settle towards the surface, and can enter into the valleys through downslope winds. More stable air at night keeps the smoke in place until the sun rises in the morning and warms the Earth’s surface. As the land heats up, it causes the air near it to rise, which in turn helps lift the smoke. By the afternoon hours, this thermal mixing begins to wane, which allows the finer particles of smoke to drift back towards the surface.
An isolated thunderstorm is possible throughout the next several days in all locations other than the coast, where morning fog and partly cloudy skies persist. As the storm threat continues, the heat does the same. In case you’re keeping count, Friday was the fourteenth triple digit day of 2014. The most triple digit days recorded in one year was 23, and that was back in 1990. If August proves to be as hot as this July, we may very well be on our way to breaking that record.
Chief Meteorologist Kate McKenna