A major stratospheric polar vortex event is in the news again.
These things happen almost every winter and always seem to be accompanied by a variety of extreme weather events at the surface. The whole process is difficult for anyone to understand, but scientists who keep working on it have made some progress. This link will take you to an interview with a researcher who is involved and can provide us with a clear overview of the main components and the basic processes that reflect changes in behavior: https://phys.org/news/2021-01-extreme-weather-stratosphere.html. I have never taken much interest in this phenomenon before, in part because the Weather Maps I study have no ongoing description of whatever is happening in the stratospheric layer that lies above the troposphere. This year, based on the work I’ve been doing in recent months, and the ideas written up as a result, I have come to a realization that the ideas may help to fill in certain of the details that the scientists are still looking for. As you might expect, my interest in pricipitable water (PW) is very much involved, but so are some of the other ideas. We’ll start with today’s image of air pressure configuration at 500hPa, about half of which looks solid and the other half totally out of whack:
All I can really say about it is that I would not be surprised to learn that the long stretch of loops and whorls was probably created by a breakdown of vortex behavior in the stratosphere, as described. If the air up there is warming it would probably expand, causing pressure changes of a type that could very well be expressed in the troposphere below in some irregular way. That’s how it looks, but mainly on just one side, which is curious. Anyway, something has happened that is causing unavoidable changes in jetstream wind activity. I don’t quite buy the idea of “the” jetstream because of complete confidence that there are three distinct kinds of pathway formations, each bearing separate wind streams, the strength of which largely depends on relative positioning of the pathways. The blue zone, green zone and red zone each contain their own means of control over one of the pathways, based on the way certain air pressure differentials are established. When these differentials become badly disordered so do the pathways, as we see in in this image, primarily on the lower/right side:
Here is where PW comes into play. High-altitude concentrated streams of PW, which on a daily basis enter the upper part of the troposphere into the same space occupied by jetstreams, are in constant motion. Their courses of progress are inevitably altered by jetstream wind activity, depending on the nature and regularity of that activity. When winds on the blue and green zone fringe pathways are weak and disorderly, like they are on the lower right side, the PW streams tend to make considerable progress in a poleward direction. When these same pathways are orderly and in close proximity with each other, as in the upper left, the winds remain strong and tend to physically steer incoming PW streams away from higher latitudes. We can see both of these effects at work in this image:
Those of us who believe that PW conveys a powerful greenhouse effect, regardless of variations in where it resides in the atmosphere, are always looking for relationships between PW maps and temperature anomaly maps, as revealed by how their images intersect in various locations. After I bring up today’s anomaly map you may be able to spot a few of the expected relationships. In summary, everything now happening in the troposphere fits together as well as ever today, starting with unusual effects due to alterations that exist in air pressure configuration, but I still don’t understand why half of the total configuration should be in tatters because of the vortex breakdown while the other half remains so solid.
Please note that all six numbers below this image, netting out the highs and lows as they occur, have changed very little from totals reported in other recent days.
Carl