PORTLAND, Ore. (KOIN) — If you’ve found no use of your rain gear this spring, you may actually need it for your Wednesday. High pressure breaking down as an area of low pressure rides in early Wednesday morning. A strong southwest flow should help initiate rain showers from the coast to the Cascades Wednesday morning. It is likely that steady rain will be in by the early morning hours, potentially by 6 a.m. for Portland, but more likely by 7. If you’ve been heading out for a bike ride or to go for a morning walk, I would be prepared for rain for your Wednesday (that’s where the rain gear will come handy, finally). Now by mid-day, it’s possible we see that rain turn into more of showers as that front moves through and a rain shadow takes place.
When we have a southwest flow, that rain shadow is usually more lenient and rain can spill over for areas like Madras and Bend. I would count on a chance for that to occur Wednesday, but it does look like it transitions over to more of a westerly orientation by midday. This will prevent most from seeing rain all day. Which at this point, we could use because of how dry it has been.
Where will we have the most saturated areas? I would count on the Cascade communities to collect some decent rain. Initially the coast and coast range will be the main target of this moisture (central).
Let’s discuss rain totals for Portland. Weather models have been hopping around the last few days but I think it is more clear as this system approaches that the total is likely going to be a bit lower than projected for the valley communities. Above is a graphic of potential rain totals, based on a collection of weather models. As you can see they range from about .25″ to .75″, with a few in the middle. My forecast is learning towards number 4, with potential for some locations to hit the forecast from number 2. I believe that rain shadow will move in and hamper some of our totals, which we were hoping for something closer to half an inch or more because of how dry it has been. Regardless, it will be the wettest day that we’ve seen this April by far. Currently the wettest day was a measly .09″.
Lastly, I don’t want to rule out a small chance for an isolated storm to pop up. If we end up with a few sun breaks in the afternoon, it’s possible for a few heavier showers.