It may seem counterintuitive, but it is true.
The movement of cooler air into western Washington and Oregon means an enhanced wildfire threat east of the Cascade crest.
The pressure pattern started to change yesterday as cooler marine air started to migrate into western Washington and Oregon.
Consider the 24-h difference in temperature between 5 PM today (Tuesday) and yesterday. Major cooling is evident from the Olympia to Eugene (around 10F) and single digit cooling over most of the remainder of the area.
You will also notice some crazy large cooling over southeast Oregon.
These thunderstorms provided welcome rain over a wide area of eastern Oregon.
The movement of cool (denser) air into western Oregon and Washington resulted in rising pressure, which produced an increasing pressure difference (gradient) across the Cascades (see forecast pressure map for 5 PM Wednesday). The solid lines are isobars, lines of constant sea level pressure.
Air speeds up as it moves from high to low pressure, with a large acceleration (from west to east) over the Cascades. These strong westerly winds then descended the eastern slopes of the Cascades.
Here are the maximum winds today. You will see 30-40 mph winds over the eastern side of the Cascades--that is due to the large pressure difference. See the crazy strong winds over southeast Oregon? Those are from the thunderstorms.
You can see the wind speed up at Ellensburg starting around noon yesterday, with gusts today getting near 40 mph.
Such strong winds are a real wildfire threat in many ways. They can help start fires (e.g, by damaging powerlines) and any fires to expand rapidly.
Just as wind accelerated yesterday, a fire started just east of Cle Elum (the Red Creek Road Fire), which is not around 50 acres.
Looking into the future, the winds east of the Cascades will increase further as western Washington cools more as deeper cool air floods the region.
The forecast from 8 PM tomorrow has strong winds pushing over and down the Cascades' eastern slopes.
Yes, cooling can result in an enhanced wildfire threat.
This should increase wind power generation just as the reduced westside temperatures will reduce air-conditioning demand. Too bad it’s not the other way around…
ReplyDeleteSame in the winter. That's the way it is with wind. When it's needed the most, it poops out and dies. Yet we keep building more and more of the hideous things.
DeleteIf only we could move power through some kind of lines.
DeleteIt is quite interesting that cooler weather can increase the threat of wildfires. We are quite used to associating warmer weather with wildfires, but not cooler weather. Thank you for sharing this important information.
ReplyDeleteIt's not the temperature, it's the wind.
DeleteHi JHK. I acknowledge that it is the wind and not the temperature that can increase the threat of wildfires. That being said, I believe it is fair to say that most people around here are more likely to associate warmer weather conditions, including warmer air, with wildfires versus cooler weather conditions, including cooler air. I for one think don't think about the risk of wildfires as much when it there is cooler air outside compared to when there is warmer air outside, although that will now change thanks to Professor Mass' enlightening post.
DeleteKELN Ellensburg had a 45mph gust at 5:53 today 6/12/2025. Now shifting from NW to WNW.
ReplyDelete