Back in June, most extended forecasts were calling for near or slightly cooler-than-average temperatures for the Pacific Northwest with near or slightly below-average precipitation. It was a reasonable forecast; after all, we had just gone through one of the wettest and coolest springs on record, and a moderate La Nina was expected to persist through the summer.
But weather is anything if predictable. And the weather this summer ended up being much drier and warmer-than-average, with numerous temperature and precipitation records set across the Pacific Northwest. Seattle recorded an astonishing 12 days of 90-degree temperatures or higher this summer, and Portland saw 67 consecutive days without measurable precipitation, second only to 1967’s record of 71 days.
Although fire season had a late start and was not as severe as recent seasons, fire danger has been well-above-average this autumn. Between April 1 and June 30, Portland saw 12.60″ of rain – the highest total on record for that span. But from July 1 through Oct 14, Portland has only seen 0.48″ of rain – the lowest total on record for that span. The late start to fire season helped reduce the number of active fires that would have grown during the September 9-10 offshore flow event for Western WA/OR, but the continued dry and warm weather has allowed high fire danger to persist well beyond its seasonal norms. Just last Sunday, the Nakia Creek fire was ignited near Larch Mountain, Washington, and it is now at a size of 156 acres and continues to burn in steep, remote terrain.
Credit: Northwest Interagency Coordination Center
This fire will cease to be a threat by next weekend as a much more stormy, typical, late October pattern finally arrives to the Pacific Northwest. But this weekend will be summer’s “Grand Finale,” with record temperatures, brilliant sunshine, and widespread haze in the Pacific Northwest.
To summarize:
- Expect record highs across Western Washington and Oregon today and tomorrow with widespread smoke, strongest on Saturday. Red Flag Warnings are in effect for the Cascades due to dry, offshore flow and critical fire conditions.
- Temperatures will cool next week but will remain above average with dry conditions. Less smoke due to weak onshore flow.
- A major pattern change to “typical” winter weather arrives on Friday/Saturday, with cool and rainy conditions persisting through at least early next week.
The Pattern:
The past several weeks have seen record temperatures throughout the Pacific Northwest, with Portland seeing the most 80-degree October days on record and both Seattle and Portland setting multiple daily temperature records. This has been due to a persistent ridge of high pressure centered over the Northwest coupled with periods of dry, warm, offshore flow.
This weekend will feature that pattern – on steroids. Not only do we have a strong ridge with warm air just offshore, but we have a deep trough with cool air over the Upper Midwest.
Credit: WeatherTogether Models
With this pattern, we see cool air and high pressure inland, and warmer air with lower pressure offshore. The result is warm, dry offshore flow into Western Washington and Oregon.
Credit: University of Washington
The Smoke
The offshore flow has brought increasing smoke from Cascade fires into the Western Washington lowlands. I’m watching the Mariners game right now as I type this, and the smoke is noticeable at T-Mobile Park. Most places across Puget Sound are now in the “unhealthy” to “very unhealthy” range.
Air quality has been decreasing throughout the day due to offshore flow, and it is now in the “Unhealthy” to “Very Unhealthy” range for Puget Sound.
Unfortunately, it’s the price we pay for record October highs when there are fires burning to our east. #wawx #orwx pic.twitter.com/LdjzcPj3g3
— Charlie Phillips (@WeatherPhillips) October 15, 2022
The smoke should continue to increase throughout the day, but we should see decreasing smoke tomorrow as offshore winds weaken and smoke disperses offshore. Still smoky – just not quite as bad.
HRRR-Smoke model
Next week will feature a return to light onshore flow, with cooler temperatures, partly cloudy conditions, and little smoke. You’ll notice the chilly mornings, but otherwise conditions will be quite pleasant.
The long-advertised switch to much cooler and wetter weather arrives next weekend. Rain should begin Friday/Saturday and a series of systems should keep things wet through at least the weekend. It’s common to see a switch to typical, rainy weather in the third week of October, and it looks like this year will be no different.
The record warmth and smoky skies will be a distant memory by next weekend. Precipitation begins Fri-Sat, and if current models are correct, we could see several inches of rain in the mountains by the middle of next week. #wawx #orwx pic.twitter.com/DPKRqEgUuj
— Charlie Phillips (@WeatherPhillips) October 15, 2022
Enjoy our final week of warm and dry weather!
Charlie
