PORTLAND, Ore. (KOIN) – Hold up, it’s not October yet, right?
Monday would be a great day to test out a Halloween costume, because it is exactly what October 31 would feel like on a gloomy wet day: temperatures in the upper 50s and enough rain to soak your costume.
After spending as much time in the 80s this month as we could, we are barely pushing the 60s Monday afternoon. A cool fall trough is moving through the region and it won’t leave until Tuesday night. I’m not sure who has been ordering up the rain lately, but it is exactly what we need. It will help squash the wildfires that are trying to hang around after last week’s rain and it may help improve the drought conditions for some.
It’s an expansive system that is spiraling off the coast of Juneau, Alaska, resulting in a steady stream of clouds trailing from the north to that low, all the way south to California and out to the Pacific. It’s a good sign for rain when we have a stratiform (low-layered clouds) deck of clouds spreading across the Pacific Northwest (PNW).
Focus your attention to the west of that for a moment as we watch the clouds crack and we can pick up the ocean from the satellite imagery. That is going to be the cool unsettled air of the trough that keeps us on our feet through Tuesday. This is when we may have downpours and isolated thunderstorms. We will break that down in a section below.
Here is another way to visualize the system that is moving through today. You can see how the bend in the jet stream settles around San Francisco, California. Pressure lowers to the north and cool and cloudy conditions take over.
Where that massive ridge has formed to the east out in the Wyoming region, you can see how it’s a clear sky on the visible satellite above. When you have such a large pool of cold air in place, it takes some time to move that air. Count on the late October weather for another day.
Now that we can see the beautiful art of mother nature, it comes with rainy prize. Expect the rest of today to be on and off wet. If you have anything that is going to take you outdoors today, it’s manageable, but you’ll want the rain gear. Even when the sun breaks show up, you will want to have the rain gear handy. Expect soggy ground in some locations and plenty of puddles to avoid. There is a chance for more rain to come on Thursday, but that forecast could trend out of the picture in the next 24 hours. Just be wary of a fast-paced system rolling across before the weekend.
Most of the morning and lunch hours have avoided the threat for thunderstorms. With sun breaks possible in the late afternoon, embedded thunderstorms may sprout up. The threat of that will range from Portland out to the Oregon coast and points in the green shade below. It is not a hard cutoff outside that green swath, but if you’re east of the Cascades, you shouldn’t have to worry about it today.
Here is the potential storm outlook for this evening around dinnertime. Notice that the rain becomes more scattered in nature, and is spread out in small cells or clusters. This is when the thunderstorms and downpours may develop today. If you had a wet fall soccer practice this evening, watch out for the wet ground potential for more rain. If you hear thunder, make sure everyone is indoors and covered. We are starting to enter our stormy season, which picks up in the fall as the cold unsettled air moves in.