SEATTLE (AP) — What was expected to be one of the strongest storms in the northwest U.S. in decades arrived Tuesday evening, knocking out power and downing trees across the region.
The Weather Prediction Center issued excessive rainfall risks beginning Tuesday and lasting through Friday as the strongest atmospheric river — a large plume of moisture — that California and the Pacific Northwest has seen this season bears down on the region. The storm system is considered a “ bomb cyclone ,” which occurs when a cyclone intensifies rapidly. The areas that could see particularly severe rainfall will likely reach from the south of Portland, Oregon, to the north of the San Francisco area, said Richard Bann, a meteorologist with the National Weather Service Weather Prediction Center.
“Be aware of the risk of flash flooding at lower elevations and winter storms at higher elevations. This is going to be an impactful event,” he said. Hurricane-force winds, which are gusts above 75 mph (121 kph), could be felt along the Oregon coast, according to the National Weather Service in Medford, Oregon.
And near Seattle, conditions for a “mountain wave” were shaping up, bringing large, low elevation wind gusts that could cause widespread power outages and downed trees, said Larry O’Neill, director of the Oregon Climate Service and Oregon State University associate professor. “This will be pretty strong in terms of the last 10 or 20 years,” he said. "We’ve only seen a coup.
