Back to the maps. As you may already know, Siberia has had record -breaking temperature anomalies throughout the month of May—to an extreme degree, as now officially announced: https://phys.org/news/2020-06-warmest-siberia-10c-hotter.html. Many of these letters during the month have dealt with a possible mechanism of explanation, ending up with the advancement of a fairly complete theory of causation centered on the greenhouse powers of water vapor. May is over with but the unusual warming of large swathes of Siberia and the Arctic region as a whole has continued every day so far in June. This morning I found an excellent example of the operation of a high-altitude stream of precipitable water from start to finish, ending with a large-sized patch of extreme anomaly—up to 15-16C in spots—in northeastern Siberia. You can see it here as a bar-shaped object in the upper right of this map:
Unlike the larger anomaly one to the left this one looked interesting because it appeared to originate from somewhere in the middle of the Pacific Ocean and thus might be fun to check out. One thing I did right away was to open the Precipitation/Cloud map to see if there was an area of reasonably clear sky over water that was warm enough to serve as the source of a major stream. I found a good prospect, which you can see in abundance on this map around its far right edge:
I just put my finger on the screen about where a little green dot is sitting and clicked on Sea Surface Temperature to see how that looked. No problem at all, with plenty of water around at 27-28C:
Now it was time for the main event. Would there actually be a nice, strong stream of vapor heading north from that part of the ocean? Again, nothing to disappoint. Vapors emerge at 40kg, then switch down to lasting readings around 20-25 kg, which is more than enough to give air temperatures a big jolt even if losses from raining out are considerable as the trek proceeds north:
What actually happened was that much vapor did condense and rain out on the way north, as seen on the second chart above, but enough remained to create a warm anomaly track in spite of it, meaning those rains were either relatively light or sporadic in terms of associated cloudiness. The stream finally ended when it got blocked, so happening all along the coast of the Arctic Ocean, by a jetstream pathway that existed in that location due to the particular shape of the high-level air pressure configuration at that time. The jetstream itself is not strong enough to be visible here, but its path can be identified on the 500hPa chart below by following the outer edge of the dark green color band. When the water stream was blocked it did not disappear but just spread out sideways, in both directions, as far as the jets would allow. This chart also shows how little there was in the way of defensive wind paths that could impede the progress of all that water before it was finally blocked. The larger anomaly that formed to the west, on the other side of the big green bulge, was created by vapor streams that had even easier access, and ultimately had surviving vapors that moved all the way to the pole’s edge.
There are always four or five streams like these trying to break through the jetstream defenses that surround each pole. In the north they are succeeding because the defenses are so badly deteriorated, with no real hope for recovery now in sight. More and more of these extreme anomalies and the problems they create can thus be expected.
Carl