An example of how an encounter between a massive high-altitude water stream and a complex jetstream caused a number of interesting temperature anomalies at the surface down below. The water stream is the one now sweeping through the eastern half of the 48 states, quite familiar to most of us. I will show the jetstream first. It is complex because it consists of two high-speed legs that are part of one stream that has passed through a long and skinny loop extending beyond the legs, better seen in the image that will follow. The weak leg to the left has winds moving almost straight north while the stronger wind to the right is moving both to the south and east:
We need to take a quick look at the ridiculously convoluted air pressure configuration up high that produced the complexity. The jetstream we are seeing is the one that traces the yellow band pathway bordering the dark green zone, often bleeding as it twists. We will see later how the skinny loop allows parts of the water stream to sneak through the passage space between the two jets and continue on much farther north:
The next image shows the precipitable water stream, which appears to have been drawn partly from the Atlantic side as well as the remains of tropical storm Cristobol after it had crossed the Gulf. The water stream is obviously being checked and shaped on both sides by the pair of jetstream winds. Note the way vapors are bleeding through the weaker jet on the left as that leg also helps to carry most of them along in their preferred northward direction of travel. On the right side, the strong southeasterly wind can be seen turning part of the water stream around and heading it back toward the New England region. We can also see how much of the water has managed to slip through the gap between the legs where the loop begins, from whence it has clear sailing much farther north. It swings past the edge of Alaska, turns toward the Arctic Ocean, and finally sends a few bits right up to the pole itself. Success!
Now its time to see how all this has resulted in a variety of temperature anomalies, with one big surprise thrown in. As expected, the states that have the added vapor have been warmed, more so in the north than the south. On the outer sides of the jetstream legs, which the water stream has been kept from reaching, the result indicates that vapor content has been left below its usual average for this date, causing below normal temperature readings. The big surprise is in the north, covering the water path we observe in the above image as it progresses between Ontario and Alaska. Why do we see such a massive cold anomaly in the presence of all that vapor? (An answer will follow.)
The path of the water stream from Ontario to Alaska is marked in its entirety by heavy cloud cover, plus patches of rain. The albedo effect thus created will always block a considerable amount of the solar energy that would otherwise be warming the ground during the daytime period. A reduction of energy flux coming out of the ground, the same kind that normally follows from day to night, will naturally neutralize or weaken whatever greenhouse warming powers are in place at the time. The degree of weakening in this case seems exceptionally high, requiring more thought to be given toward explaining the possible reason. Back in the lower states, meanwhile, we see similar amounts of cloud cover and rainfall and yet a positive warming anomaly has easily survived. Why such a difference? What I am thinking, just offhand, is that in the south we have had plenty of hot sunshine and warm nights in the previous two days before this occurrence, probably leaving the ground in an unusually warm state that could extend a strong outflux for a number of extra hours. The Canadian region may have completely lacked that advantage, or even been unusually cooled for a couple of preceding days. I don’t have good information to go by, but the concept is interesting in any event.
Carl