Atmospheric river eyes the PNW this week; how much rain will Oregon see?

Weather

PORTLAND, Ore. (KOIN) – After last week, do we really need another soaking of rain?

We can always use the rain and the snow to help improve the drought conditions, but we don’t always want it all at once. Before we call it a dry week, we have another atmospheric river coming our way. However, it appears this ribbon of moisture will stay north of Oregon for most of the week. Will we have to worry about the rivers again this week? There will be concerns this week, mostly to the north.

Last week we had 3.83 inches of rain at the Portland Airport. We are not expecting that much rain this week. Not even close to it. How does one atmospheric river impact the region more than the other? It all depends on the axis of the moisture and how long it sticks around. The atmospheric river moving in this week will stay tilted to the north, mainly impacting Washington and Vancouver Island.

FORECAST

Each day this week will bring in a threat for some scattered showers around the region. For Portland and most communities around the area, we should only experience rain Monday, Tuesday, and Thursday. Instead of a massive hose of moisture impacting us this week, we will just have fringe showers. The remainder of Monday is going to be mainly dry, with just a few isolated showers.

Tuesday has the potential to be wet from Astoria north. This may also impact the northern Willamette Valley as the atmospheric river stretches to the north. You can swipe through the slideshow below to get an idea of the situation at hand. The moisture is backed all the way south to Hawaii, which is what we refer to as a Pineapple Express.

Check out the forecast rain total for the next five days. There will be a sharp difference from areas of Cowlitz County down south to Marion County. This goes for the Oregon coast as well, as the heavy rain will be to the north, near Astoria. Astoria will be real close to picking up some impressive rain totals this week. I’m not ruling out the northwest Oregon coast from picking up multiple inches of rain this week.

The weather model is projecting anywhere from an inch to two inches, with totals across the way in Washington up near the Olympic Peninsula in the two- to four-inch range. This type of forecast will keep the flooding to the north, potentially clipping part of the northwest Oregon coast.

Thursday may bring another splash of rain for the Willamette Valley before the forecast dries up on Friday. If you’re traveling north this week, you will want to be prepared for wet travel.

There is a flood watch in place for some counties in Washington. Right now there are no flood alerts for our viewing area here in Oregon. That flood watch is because of the targeting atmospheric river bringing in excessive rainfall.

Most of the rivers have receded from peak crest last week, but there are still some vulnerable areas. Cycle to the next graphic to see how the river stages are faring early this week. There are only a select few locations in Oregon that are still in the near flood stage. That happens to be the Tualatin River that crosses through Dilley and Farmington. Both projected to lower below the yellow (near flood stage) mark by the end of the week. We have no issues locally with the rivers at this time, but many are still running high from last week.

Washington is in a different boat, as the Chehalis river is still lofty in many locations. That is why the flood watch is in place for that area of Washington this week. The atmospheric river will bring in some more rain and likely additional flood warnings this week.

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