Oregon moving into long-term cool and wet weather pattern as La Niña takes hold
Nov 06, 2020
After a generally dry and mild autumn, the switch is about to get flipped across Western Oregon.
Warm autumn days are about to transform into a steady barrage of either rain or chilly temperatures as more typical November and December weather arrives in force, meteorologists said.
Anywhere from one to two inches of rain is expected late this week, followed by temperatures as low as 31 degrees over the weekend in the Willamette Valley. Some snow is expected in the mountains — though not a ton — followed by more rain, cold days and possible snow next week.
"There's nothing in our models that suggests we're going to have any more of those warmer or drier patterns anytime soon," National Weather Service meteorologist Briana Phillips said. "We can say with confidence that we're moving into a more typical fall and winter pattern of cooler and wetter weather."
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While it might not seem even a bit shocking that Oregon will get some rain and chill at the beginning of November, the vast majority of the state has been way below normal in terms of precipitation going back a full year.
Salem and Eugene had their eighth- and fifth-driest water years on record, respectively, and a whopping 41 percent of Oregon is currently in "extreme drought," according to the U.S. Drought Monitor that tracks precipitation against historical norms.
In addition, Western Oregon had an extremely dry start to the last rainy season, particularly in November and December, which got so bad it spurred a salmon die-off on the Oregon Coast when a parasite was able to spread from fish to fish trapped in low water rivers and creeks.
“This scale of die-off is really unheard of,” Robert Bradley, district fish biologist for the Oregon Department of Fish and Wildlife's North Coast Watershed District, said last December. “This parasite typically doesn’t escalate to this level.”
A person rides their bike through Bush's Pasture Park on in late October. Fall color will be winding down as more rain is set to arrive in the Willamette Valley.
This year, forecasters are predicting the opposite. A strong La Niña typically leads to cooler and wetter weather, Phillips said, and while that didn't show up this October, it's expected to make November, December, January and February cool, wet and snowy.
"We're trending into a time when the influence of La Niña should be heavier, and in looking at what we have forecast right now, that seems right," she said. "We do get a break from the rain over the weekend, but then the rain returns next week and there's another system behind that one.
"So I think it's safe to say that we're settling into more of a typical winter weather pattern."
Zach Urness has been an outdoors reporter, photographer and videographer in Oregon for 12 years. To support his work,subscribe to the Statesman Journal. Urness is the author of “Best Hikes with Kids: Oregon” and “Hiking Southern Oregon.” He can be reached at zurness@StatesmanJournal.com or (503) 399-6801. Find him on Twitter at @ZachsORoutdoors.
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