Power outages reported in windy atmospheric river
QuickTake:
Blustery wet weather is rolling through the Willamette Valley this week, and forecasters said a funnel cloud was possible.
The third atmospheric river in a string of storms is sweeping through Eugene and Springfield on Wednesday, bringing heavy rain and winds that have caused scattered power outages.
Springfield Utility Board reported 50 outages, which have since been restored, early Wednesday afternoon.
Winds could be strong enough to briefly spin up a funnel cloud or weak tornado, according to the National Weather Service. In the Willamette Valley, tornadoes typically stay on the ground only briefly, said David Bishop, a meteorologist with the Portland office of the weather service.
“We do not get the long-lived, long-track tornadoes of the Midwest,” he said. “Most [here] would be on the ground for a few minutes at best, and typically produce max wind gusts under 100 miles per hour.”
Forecasters said there was a marginal risk of severe thunderstorms through early Wednesday evening resulting in such tornados. It could also produce waterspouts or hail.
Winds are expected to be strongest Wednesday with gusts of 35-45 mph across the Willamette Valley and up to 55 mph along the coast overnight.
By late Wednesday morning, steady wind moved through the southern valley with rain, which could total to half to an inch by the end of the week.
The storm system is part of a moderate to strong atmospheric river expected to taper off later Wednesday, with another, weaker front arriving Thursday. Showers are likely Friday before conditions dry out for the weekend.
While the atmospheric rivers — a long, narrow band of concentrated moisture that moves through the air – keep coming, the frequency isn’t necessarily unusual, Bishop said.
“We go through periods where we can have an active fall pattern with a lot of precipitation, and there are times when the fall can be on the relatively dry side,” he said. “It’s not out of the ordinary to get a few back-to-back atmospheric rivers, especially in a more active pattern.”
Atmospheric rivers are a natural part of the water cycle in the Pacific Northwest, often marking the end of wildfire season and helping replenish water supplies. However, their intensity and frequency is projected to change, according to the U.S. Department of Agriculture’s Northwest Climate Hub.
Peer-reviewed research shows that as the atmosphere warms, it holds more moisture — and when strong winds drive that moisture inland, it can unleash heavier, faster rainfall, like a sponge being wrung out.
In this round, forecasters say, the rain is beneficial — especially as the Willamette Valley recovers from drought that left soils so hard that moisture once pooled rather than soaked in. This week’s rainfall is helping to saturate the ground.
— Lillian Schrock-Clevenger contributed to this report.