PORTLAND, Ore. (KOIN) — The latest National Weather Service Climate Prediction Center report shows a 50 to 60% chance of above-average rainfall for Western Oregon and Washington next week.
Timing will adjust as we move closer to these events, but one storm may move in late Sunday night to Monday morning, and the other on Wednesday morning.
There are also some hints that these systems could get a boost of tropical moisture from one or two weak to moderate atmospheric rivers. Atmospheric rivers are a stem of moisture, branching from the tropics, that can “attach” to Pacific storms and bring in heavier rain and windier conditions.
Forecast rain totals next week span anywhere from 3″ to 5″ at the coastline and mountains and around 1.5″ to 3″ in the Willamette Valley.
Rainfall in Washington also looks heavy with 3″+ forecast across the majority of the western region.
Showers are also expected early Wednesday morning after 2 a.m. There’s a 50% chance that the overnight rainfall will continue into the daytime hours. KOIN 6 Meteorologist Kelley Bayern reports that raincoat season is almost here as the region shifts toward fall weather.
“Next week looks rainy and cool as a couple of large storm systems arrive,” Bayern said. “Have the rain jacket and fall wear on standby.”
This rainfall will be beneficial to the area as we continue to extinguish wildfires and reverse our drought. However, too much rain all at once is never a good thing.
Atmospheric rivers all also tricky in where they line up, causing uncertainty in exact rainfall amounts we’ll see across the region next week, as well of the timing of it all. Rainfall totals will likely back off a bit, as they tend to do, when we forecast five to seven days in advance.