It's October, and that means it's inversion season in Washington.
Tuesday's 5 a.m. sounding, a vertical snapshot of the atmosphere measured by a weather balloon launched by the National Weather Service, shows a stout inversion above Spokane. The red temperature line increases sharply to the right in the lowest levels of the atmosphere. The surface temperature was a cool 46°F but warmed to a balmy 63°F approximately 1300 feet off the ground.
Anyone who has lived in Washington for a while knows that a clear, calm evening usually leads to a hazy start to the following day. Monday night to Tuesday morning was no exception.
Although air quality has been GOOD for most of the state, Yakima has maintained MODERATE air quality since Monday evening. Similar readings were observed further down the Yakima Valley into the Tri-Cities as well. The effects of this inversion could be seen from the Yakima Air Terminal webcam.
This low level haze will be a common refrain in the coming days and, until the storm track shifts south, potentially weeks.
Another item to watch will be wildfire smoke to our south.
Satellite imagery Tuesday afternoon shows several active fires and associated smoke plumes in Oregon and Idaho. Some of this may drift overhead in the coming days depending on smoke output. This weekend, in particular, will be the timeframe to watch as a ridge of high pressure extends into the northwestern U.S.
Should fire activity produce sizeable smoke plumes, some smoke could drift into Washington. It's unlikely to have widespread impacts on air quality, but it is something to monitor as wildfire season seemingly refuses to end in the northwest.
