Some of the things I have been writing about lately are coming into full bloom, creating images on the weather maps that serve well as illustrations. We certainly want to know what will happen if and when the blue zone on the high-altitude air pressure map goes away? That day may not be too far off. A large chunk of the blue zone is being pinched off right at this time, as you see here, and we’ll soon find out that significant consequences have already begun to make an appearance.
The border that marks the regular location of the blue-zone jetstream pathway is now seriously disfigured, probably enough to cause some weakening in the strength of its winds. Meanwhile, the green zone as a whole must fill in the spatial gaps in the blue zone, creating conditions that are likely to leave its border and jetstream pathway in a state of distortion and confusion as well as weakness. We can see all of this on the map:.
Take some time to check out the way today’s green-zone jet winds are positioned. As always, they are following the outer border of the zone, but in this case the location of the border has become uncertain, causing the main pathway to split apart in places. The only time we can see much strength in these winds is in the few places where the pathway comes into close proximity with either the red-zone winds or the much-weakened blue-zone stream. Just the observed twisting and turning of the blue and green pathways is a factor that by itself reduces wind speeds. Think of how race cars on an oval track speed up on the straightaways and slow down for the turns.
In yesterday’s letter I promised to elaborate on the consequences of this type of jetstream breakdown, and that was my plan for today. I did not expect to be handed such an immediate and vivid illustration. A key point in my entire hypothesis regarding these upper-level theatrics is that the movement of streaming concentrations of precipitable water (PW) at that upper level is largely determined by the strength and positioning of the jetstream winds that constantly roam through the area in their own variety of concentrations. The PW streams always have a natural tendency to head poleward as they move, while jetstream winds tend to move from west to east in a wavelike pattern. The jets often give the PW an assist if they are both headed in that same direction. In other situations, which will be more often, they either get in the way or steer them off to the side. This latter capability can be watered down in either of two principal ways, by an absence of normal positioning or loss of normal velocity. We can see all of these effects on the PW map today, ending with a thumb-like penetration that takes a large concentration of PW well into the central part of the Arctic Ocean. The direct poleward movement of a strong type of jet that we saw in the previous image was helpful at first, followed by an absence of any amount of usual blue-zone blockage being in place until the very end:
When you see so much PW in a totally unexpected place, where its normal concentration would be minimal, you can expect an enlarged area of warm anomaly to emerge, and that is exactly what we get on the next map. The brightest red spot near the top designates a temperature increase that is 18-21 C above normal. It’s the kind of increase you get when the total PW concentration for the day is about four times greater than its baseline average from the same period. This is for only a single day. We don’t know what tomorrow will bring, but I have a feeling it will, at minimum, be interesting, with so much fast action on the scene.
Carl