PORTLAND, Oregon โ A stream of atmospheric rivers will flow through parts of the Pacific Northwest in early December, dramatically changing the region's most recent cool, dry fall, a seemingly rare occurrence. The Portland office of the National Weather Service (NWS) predicts that up to three atmospheric rivers will hit the region, bringing a very active weather pattern that will dump plenty of rain at lower elevations and snow in the Cascades.
The National Weather Service forecast discussion mentions that there is some uncertainty with the prediction but rain, snow and wind are expected. It continues, โaside from the hazardous travel conditions through the Cascade Passes during this time, flooding concerns will begin to increase along rivers, streams, small streams, and in urban areas with poor drainage, as levels of the rivers will already be high before the second round. of heavy rainfall.โ
Model-based predictions and events like this captivate Northwest Division Reservoir Control Center (RCC) personnel as they monitor and prepare to adjust operations at U.S. Army Corps of Engineers dams. (USACE) and the Bureau of Reclamation. Both federal agencies are working together to reduce flooding at major dams in the Columbia River Basin. These agencies also work with entities in Canada, other dam operators, the Bonneville Power Administration (BPA), and storm fish managers.
Catherine Dudgeon, a hydraulic engineer and water regulator at the RCC, is responsible for tracking this particular weather event.
"Overall, I don't feel worried or stressed," Dudgeon said. "I actually expect a lot of this precipitation to be absorbed into the ground and I hope this can help with snow accumulation, which is important for next spring," he said. โThat said, all models are wrong, some are useful. โSometimes we have to wait to see what we get.โ
At this time, RCC does not anticipate adjusting operations on the Columbia River because most of the rain will be beneficial as conditions have been dry throughout the basin. Most storage projects in the basin have some reservoir space to store water, if necessary. Aaron Marshall, acting chief of RCC, anticipates the most significant impacts will be in Western Washington, primarily on unregulated rivers and streams.
"However, these atmospheric river events are very unpredictable, so we will track them and adjust operations if necessary," Marshall said. โThe Portland district will make some adjustments to the Willamette Valley projects, but even there we don't see any planned checkpoints reaching flood stage with this event,โ he said. โIt is important for people to remember that these atmospheric river phenomena are difficult to forecast with much confidence and that small streams and rivers can be striking and grow very quickly. For travelers, we expect heavy wet snowfall in the Cascades, which will create hazardous driving conditions.โ
Dudgeon won't be alone as other RCC members will be monitoring the weather system throughout the weekend and providing support as needed.
โAmong our Reservoir Regulation team in the Division, we also have the districts, BPA and Reclamation as partners to help during flooding,โ Dudgeon said. "It really is a team effort!"
For now, the NWS forecasts that the Columbia River in Vancouver will remain below eight feet (flood stage is 16 feet), so water regulators do not anticipate the need to implement flood risk management actions. floods. However, the RCC would first adjust the Grand Coulee Dam reservoir in northeast Washington. They would then modify the John Day Dam reservoir if they began to see potential for Vancouver to reach flood stage.
