Surprise 11″ of Cascade Concrete.
I swear the minute I hit send on my last blog I got a notice that there was more very cold air coming. In fact it turned out to be a little colder than the latest cold snap we’ve recorded since 1960. Thats a LONG time ago, especially in weather records for us. La Nina certainly decided to drag this thing out. The surprise intensity of the snowstorm was kind of a shock. I came home from work early after begging my ride and business partner to go, just as we left our wholesale nursery in Sherwood it changed to huge fat flakes. By the time we got to my home in north Portland it had already accumulated to 3″- I proceeded to get a total of 11.1″. Greg went to the shop and then it took him 4.5 hours to get home. I’ve lived here my whole life, you leave BEFORE the snowflakes become apparent. And if the temperature hits 34F and its dropping and precipitating you go immediately then too. No questions you just go. Also, there are such things as traffic cams and they are incredibly useful when you are begging someone to leave.
Overview- where the hell is spring?
This is a topic probably for debate but I’ve noticed a pattern. Our weather is stagnating. In late December a huge parcel of arctic air moved from Siberia over N. China where they recorded their coldest modern reading of -53ºF . That dome of cold air then moved over the Korean Peninsula into Japan. Both nations reported their coldest weather in 10 years. and it lasted for several weeks. It was a long pattern. Prior to our cold wave in December the British Isles were hit with the coldest air in many years and cold weather trailed all the way to the Iberian Peninsula. And you might have noticed the snow in Turkey during their catastrophic earthquakes. Many people were up in the middle of the night to take pictures of snow on Palm trees and Ziggurats and therefore, were also filming when the quake hit. The videos are truly chilling and everyone should watch them.- But what I’m describing is a very WAVY jet stream. Rather than the jet stream strongly flowing around the N and S. hemispheres and trapping the arctic air around the poles, the jet stream begins to wobble and get wavy. Remember that the jet stream is formed by the temperature gradient between the cold poles and warm equator. it meets at about 45ºN. So, a strong pressure gradient means a strong jet steam. When there is less of a gradient- and the poles are heating at least 4x as fast as the Equator- the jet stream which used to be penned in is now allowed to wobble. Even more potentially troubling it may also be losing its momentum. Therefore, you get cold air plunging south, warm air surging north and what used to be a fairly linear Jet stream now lacks momentum to push these huge systems along. Weather gets stuck.
There’s a trough stuck to my shoe
I mention this because our weather has been stuck on the West Coast for more than three weeks and it looks to continue. A huge wobble in the jet stream has produced a very strong stationary high pressure in the Gulf of Alaska and a very persistent trough ( the cold side of the jet stream) just to the east of it that has spilled south and lingered. Our flow has been from The Yukon and BC south all the way to north Baja. This stalled trough is responsible for both the cold air and the stormogenesis that repeatedly pushed into California and they received prodigious rain and snows all the way to the Mexican border. For us it has been repeated bouts of low elevation snow and cold temperatures One low pressure system after another rolls straight down our coast. Luckily, we have not had another bout of modified arctic air that was pulled out of the Gorge during the big snowstorm which caused our coldest temperature of the year. The last few weeks have lacked real arctic influence instead its been a steady stream of lows tracking down the coast with cold modified maritime arctic air. Its been cold, gray, flakey and its delayed spring. We get set ups like this many times but this one seems different. Combined with the extended record high temperatures in the East and cold in the West it is literally record breaking polar opposites. In reality we will only see how anomalous this pattern has been and historic after many years of perspective. From my point of view it has been more than historic.
West coast flood scenario
The forecast is actually kind of ominous. It looks like this cold trough might be shunted east by an Atmospheric River (AR). This would have tropical origins and which would load it with moisture and it has some extra warmth. For the PNW it would be early next week. It appears the largest Atmospheric River is right now occurring in Central and Northern California streaming huge quantities of latent moisture into the state. Unfortunately, California ( and possibly Oregon ) could experience what is called RoS A rain on snow event. Because of the persistence of this cold trough, repeated low elevation snows have occurred as far south as Southern California. In Oregon the snow level has not risen above 2000′ appreciably for weeks and there is a lot of snow from 1500′ to 3000′. The incoming AR will shove the snow level up to 8000′ in California and 5000′ in the PNW. Everything below those elevations will have rain on snow and will melt possibly rapidly. This is the classic flood scenario for the west coast. Some of our most historic floods were RoS events. 1964, 1996 the last two colossal floods were rain on snow events. In Oregon its too far out to tell if we will have these effects. In California it is happening right now . Surprisingly, the best hope to staunch a RoS event is for cold air to spill in and lower the freezing level inhibiting the melt. So, its complex.
All of the extended forecasts now predict below normal temperatures though the end of this month. But, it will not be modified maritime arctic air cold it will be Maritime cool. What that means is that instead of highs in the 40’s and lows in the 30’s we’ll likely have lows in the 40’s and highs in the 50’s. That might not sound like much but to plants- who are also responding to longer days it means it’s time to grow. So, after weeks of incredibly slow progress we should see spring start to speed up.
Xera Plants is open 10-5 Friday and Saturday this week
Hours change to 10-6pm the following Thursday (Yay Day light Savings).