Well-defined cold front moving in Thursday


PORTLAND, Ore. (KOIN) – Three days of rain in one week! Can you believe it? That spring rain jacket is getting some use finally.

There haven’t been many opportunities this spring to discuss an incoming rain event, but we have found a few tucked into our final week of May.

We have an area of low pressure off the coast that is going to make conditions a bit turbulent come Thursday morning. This system is likely the most defined system that we have had going back to March. More low-level moisture and energy seem to be present for widespread rain in the valley upon arrival. This will be a cold front with more vitality, increasing the wind and it will make sure just about everyone has some rain.

The GIF below is the system that is moving in our direction late Wednesday. Talk about an organized area of low-pressure churning out there. That is the type of organization that we need right now because we need a sure shot at rain. There have been too many days where we had a trace of rain and we didn’t quite strike gold. You can tell that this system is going to bring more to the table.

Rain for all! The whole state is still dealing with a drought and this is going to give us a minor boost. We are currently shy of even a half an inch of rain this month in Portland. There have been some areas around the city that collected more rain, but our observed rain is coming from the airport in northeast Portland. We finally had back-to-back days of measurable rain, but the rainfall deficit is still a ways behind (-1.57″).


This system is coming together and it should move in with vigor by the early morning. Weather models are coming in around the 5 a.m. hour west of Interstate 5 in the Willamette Valley. That means this front will arrive earlier for you folks up and down US 101 along the Oregon and Washington coast. That should collide with the coast after midnight on Wednesday and it will travel east through the morning hours. This is going to shake up the forecast for the morning today. Expect a wet commute in with moments of moderate rain. It’s possible the timing is slightly off, but I would be ready for rain by 5 a.m. with those in eastern Multnomah county or in Clackamas county to be ready for that rain closer to 6 a.m. I wouldn’t leave the house without the rain jacket in the morning.


Check out the rain totals by as early as 9:30 a.m. today! We may be pushing a quarter of an inch of rain by the time we get to mid-day. That means we are instore for a wet morning around here and that is going to potentially be the wettest span of time we’ve had over at the airport in some time. The last few days we had to depend on the full day to get some measurable rain, but this is a sure shot by morning. Rain totals pushing the half inch mark for the Oregon coast today. The deepest moisture and the target of this system does look to be farther to the north. Rain totals should be lower south of Salem to Eugene than what we are expecting in the Cowlitz valley and down through areas like Portland. The mountains will exhaust most of this system, leaving the rain totals down near a goose egg for those east of the Cascades. I still expect showers to make it to the other side, but the rain totals shouldn’t be impressive. The Dalles has the best chance for some rain, where areas like Pendleton will be on the lower end.

As you would expect with an early morning system, temperatures will be limited because of the clouds and the cold front. Temperatures in the morning right around 50 and they should warm to the lower 60s behind that cold front in the afternoon. The wind will be whistling out of the southwest, topping around 25 mph. When that cold front comes moving through, be ready for some blowing trees and moments of rain that feels aggressive. Temperatures will be warmer to the east, over near Baker City. Will we warm up much more than the lower 50s around Astoria? It may not. You will want to prepare for a cool and wet spring morning. I do anticipate the clouds to be broken post the cold front in the afternoon. That may open the door for a few heavy cells due to the ability to bring in some energy from the sun.

This system eventually clears out, leading to a nice and warm weekend. We will keep you updated on the Memorial Day weekend forecast in the coming days.

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