October is a month of changes. Leaves turn from green to red, the weather turns from sunny to stormy, and the Mariners – at least for the last 21 years – hang up their cleats until the following spring.
But not this year! We’ve just gone through one of the driest summers and early autumns on record, with Portland seeing a record 67 consecutive dry days this summer and Seattle experiencing a record 12 days of 90 degree temperatures or higher. Though the shortening days have been noticeable, our sunny afternoons have more than made up for it. And oh yeah – the Mariners are in the playoffs.
So how much summer do we have left before the rain and wind arrive? Potentially quite a bit, but the end appears to be in sight. Let’s take a look.
Smoke and the Short-Term Forecast
Air Quality Alerts are currently in effect from North/Central Puget Sound south towards the Portland Metro Area. Air quality ranges from “moderate” to “unhealthy for sensitive groups,” and the decrease in air quality is primarily due to smoke from numerous fires over the Washington Cascades, with some contribution from the Double Creek and Cedar Creek fires in Oregon. Air quality will slowly improve tomorrow and will improve more substantially on Monday as a weak trough moves inland, bringing stronger onshore flow and pushing smoke east of the Cascades.
Credit: purpleair.com
All of this smoke is due to a large ridge of high pressure over the area, with weak offshore flow bringing smoke from Cascade fires into Western Washington and Oregon.
Credit: WeatherTogether Models
I remember hoping back in June that we’d get through this summer without any major wildfire smoke issues. After such a wet spring and early summer, it seemed like a realistic wish. But since the fire weather event on 9/9-10 that spawned the Bolt Creek Fire and helped grow numerous fires along the Washington and Oregon Cascades, we’ve seen repeated periods of smoke and haze with very fleeting periods of relief. Compare the air quality before the 9/9 event to after.
Although this was one of the hottest and driest summers on record, the cool/wet spring and lack of offshore flow gave us minimal fire activity and smoke.
That all changed after the 9/9-10 offshore flow/fires, and the persistent ridging since has given us poor air quality. #wawx pic.twitter.com/6wyEQrAVrO
— Charlie Phillips (@WeatherPhillips) October 8, 2022
Forecast
After the weak, dry trough and stronger onshore flow on Monday, ridging will return and the remainder of next week should be beautiful with warm temperatures, widespread sunshine, and good air quality for most locations. Dry conditions will persist through the weekend into at least early next week. Check out the forecast from the Climate Prediction Center – it doesn’t get any clearer than this!
However, look at what happens in the 11-15 day period. Both the GFS and Euro ensembles show a transition from ridging to strong zonal flow, with a parade of strong systems off the Pacific slamming into the Pacific Northwest.
Credit: Tropical Tidbits/Levi Cowan
Unlike the gradual transition to warmer and drier weather that takes place over the spring, the transition to wet and stormy weather is often abrupt and historically has tended to occur during the third or fourth week of October, with intense storms occasionally occurring earlier in the month. The ensemble spaghetti plots also show an increase in precipitation towards the third week of October.
I suspect that two weeks from now, our warm, hazy weather will be a distant memory and we’ll have much wetter, darker, and colder weather on our hands.
In the meantime, enjoy the warm and sunny weather, and go Mariners!
Charlie