PORTLAND, Ore. (KOIN) – Have you ever thought of a pool up in the sky? Isn’t it humorous when we say there is a cold pool of air in place? I feel like there is a good joke somewhere in there.
Well, guess what, we have a cold pool of air in the vicinity of the Pacific Northwest (PNW) this week. That cold air, which becomes colder aloft, will aid in the development of scattered showers Tuesday.
What is different from Monday? Well the amount of clouds and the development of stray showers. Expect broken clouds on Tuesday. Those shaved clouds should allow for more sunshine to sneak into the forecast. That sunshine will then allow for some surface heating, and the ability for that warm air to rise and to cool down form that pool of cold air aloft.
This should trigger some shower activity around the valley Tuesday afternoon and evening. The weather pattern graphic below paints the trough dropping south and it will set up shop right there until Thursday or Friday.
Since we are discussing some cooler air, we can expect temperatures to come in below average. The morning temperatures should begin in the 40s Tuesday, with the potential for some upper 30s out there. Temperatures up on the mountain are going to be cold, too. Timberline Lodge started in the upper 20s on Monday, with freezing temperatures around 5,000 feet and above Tuesday morning as well. You may need a light jacket when you start the day.
How does that translate for the afternoon? Not quite the summer temperatures that we had last Tuesday (95 R). It’s going to be 30 degrees or so cooler than last Tuesday.
Day time highs will be mostly in the mid 60s around the Willamette Valley. The Greater Portland Metro Area may push the upper 60s, with sun breaks in the forecast. Pendleton and the Tri-Cities region should top off in the 70s. That will be the warm spot on the map and in the PNW for the day. The Oregon coast isn’t going to be that much cooler than the valley, with highs around 60.
Does Tuesday happen to be your day to support the local food cart pod? If the 60s is too chilly for you, you may want to grab a hoodie or light jacket.
What about the rain? If you look at the 7 day forecast, you may notice that there is a chance for light rain each and every day this week. There is a lot packed into this KOIN 6 weather article here, which elaborates on the rain that we’ve accumulated this year (or lack of). You can also listen in on the forecast in this weeks weather podcast.
Bringing our attention back to rain, we have minimal rain totals in the forecast Tuesday. Shower development is most likely along the coast range hills and through the higher terrain of Washington. The Oregon coast will have an opportunity to pick up some more rain, too. This is not going to be a day where we have a washout or anything remarkable. This is going to be an afternoon where the showers are limited and scattered.
Late afternoon is when we may have a few of those isolated showers floating around the valley. They should travel from the southwest to the northeast as the wind carries them through the valley. I would be most prepared for a spotty shower in the 3 PM to 6 PM window.
If you’re an afternoon or evening runner, this is the timeframe to be most ready to come across that rain. We will keep an eye out for heavier rain later in the week. For now, enjoy the cooler conditions around the PNW.