Get ready, Northwest! Another powerful atmospheric river is on its way to bring heavy rain and increase the flood threat in the region. This latest storm is expected to dump over half a foot of rain on the already-soaked area, posing a significant flood risk.
With each new atmospheric river, the flood risk continues to escalate, and this upcoming event is no exception. The Northwest is bracing for several inches of rain and feet of snow, with warmer air expected to drench even high, snow-covered elevations, further intensifying the flood threat.
Flood watches have been issued for over 10 million people across the Northwest, as heavy rain is set to target portions of Washington, Oregon, Northern California, and Idaho through Wednesday. A Level 3 moderate risk of excessive rainfall has also been declared in northwestern Washington.
Atmospheric rivers are the hallmark type of winter storm for the Northwest, directing tropical moisture from the Pacific straight to the West Coast in the form of heavy rain and snow.
This week’s event is considered a Level 4 out of 5, or “extreme,” atmospheric river for much of the Oregon coastline and a Level 3 out of 5 “strong” event for the Washington coast.
The heaviest rainfall is expected to begin Monday evening from coastal Washington and Oregon into the Cascade mountains. Parts of the Cascades that were buried in snow over the weekend may record more than a foot of rain from late Monday through Wednesday.
Outside of the mountains, rainfall amounts in western Washington and western Oregon could climb into the 3- to 6-inch range this week.
This amount of rain, falling so soon after the area was deluged with rain and snow over the weekend, will significantly impact the region. The ground’s ability to absorb more water has been reduced, raising the flood risk even further.
The first atmospheric river of this multi-day event unloaded more than four inches of rain from Saturday to Sunday on parts of Washington, Oregon, and California, further saturating the ground.
Rainfall melts snow, and that melted snow will then flow into streams and rivers, causing even higher rises on rivers or flooding low-lying areas.
As a result, some rivers in western Washington are forecast to reach moderate and major flood stage this week. The Skagit and Snoqualmie rivers are of particular concern, with both forecast to flood roads, farms, and even some residential areas in spots.
Heavy rainfall pouring down on deep snow in the mountains also poses the risk of avalanches, with an avalanche warning already in place for portions of Washington and Oregon.
Furthermore, heavy rainfall may trigger landslides or debris flows in areas burned by wildfires, as the ground is less able to absorb it effectively.
By Thursday and Friday, storm activity is forecast to scale back across much of the Northwest, but showers and some high-elevation snow remain possible.
And if that’s not enough, there are early signs in forecast computer models of yet another atmospheric river hitting the region by the early weekend. The exact strength and overall impact of this potential event should become clearer once this week’s atmospheric river comes to an end on Wednesday.
Stay safe and stay informed as the Northwest braces for another round of heavy rain and potential flooding!
Disagree. It’s about time we get a break from the dry weather and replenish our water resources!
Disagree! I love the rain, it brings a soothing ambiance and a chance to cozy up indoors with a hot cup of tea.
Disagree. Heavy rainfall can lead to flooding and other damage, making it a cause for concern for those in the Northwest region.