Two Strong Atmospheric Rivers to Bring Major Flooding To Western Washington

Just a quick blog this afternoon – I’ve gotta head out the door in a few minutes for a night shift of real-time energy trading at Puget Sound Energy. The main goal of real-time trading is to economically balance generation with system demand, and because there is system demand 24 hours a day, we need to be doing short-term trading 24 hours a day! The night shifts can indeed be tough, but the upside is that you get a lot of days off, since each shift is 12 hours and we do long stretches of both night and day shifts at a time. It’s not for everyone, but it’s a fantastic schedule if you are young, single, and want to travel the world, and the job itself teaches you a ton about energy policy and the physical operation of the power grid.

First, a quick review of the wild weather we’ve seen so far this week. A series of cool systems arriving from the WNW brought heavy mountain snow to all the passes. With the heaviest snow occurring on Tuesday 11/9. I wasn’t able to find exact statistics (most resorts are not posting snow totals yet) but I’m guessing Stevens saw at least two feet since Saturday.

–a webcam at Stevens Pass this morning, nicely framed by icicles. You might remember the long slow ride on Barrier–but now it is called the Skyline Express and zips right up the mountain. These tracks’ skiers probably had to hike up there today. pic.twitter.com/92b6Rd4oFF

— NWS Seattle (@NWSSeattle) November 10, 2021

Mt. Baker has even more snow and has a tentative opening date of Wednesday 11/17 according to their website. They have opened by Thanksgiving weekend 7 of the past 10 seasons, and with the extended forecast looking quite snowy, there’s a good chance that folks could once again get a few Turkey Turns up at Mt. Baker this year.

Tuesday was a stormy one here in the Western Washington lowlands. Tens of thousands of customers lost power due to gusty winds, and there was even a tornado warning issued for the Kitsap Peninsula based on doppler radar-indicated rotation. No tornado was observed. Additionally, many folks in the Seattle area outside of the tornado-warned region got tornado alerts on their phones. The Seattle NWS is looking into this to make sure it doesn’t happen again!

Current Conditions and Forecast:

The threat now switches from cool rain and mountain snow to a much milder pattern with heavy, flooding rains in the mountains. We have two separate “atmospheric rivers” slated to bring heavy amounts of precipitation to a region with saturated soils, high rivers, and a relatively light, uncompacted layer of high-elevation snow that will melt and add to the river flooding threat. Flood watches are in effect for all of Western Washington and NW Oregon to cover this threat.

The first atmospheric river will be aimed at Western WA & NW OR and will bring heavy rain tonight through Friday afternoon/evening, tapering from north to south.

Atmospheric river incoming! Major flooding expected for many North/Central Cascade rivers with this. pic.twitter.com/VvtGgtC4o7

— Charlie Phillips (@GeoduckChuck) November 12, 2021

The second atmospheric river will be focused a little further northward and will begin to impact the North Cascades/Southern BC Saturday night and Sunday morning. It will then very slowly drift south through Western WA Sunday evening through Monday morning before finally pushing south into Western Oregon Monday afternoon and evening.

The Snoqualmie River is expected to reach major flood stage with this first atmospheric river but only see minor flooding with the second one, though this could change if the second AR trends further south.

Meanwhile, the Skagit River further north is expected to reach major flood stage with BOTH atmospheric rivers, and should crest higher with the second AR than the first.

That’s all I have for now! Gotta head out the door to bike to work in this…