Today there is a substantial warn anomaly appearing along and above the northern coast of western Siberia, as shown on the following map, with temperatures from 5 to 10C above normal over a large area. (This is an area where averages for this day normally run a few degrees above or below freezing.) I wanted to see if the extra warmth could be traced to movement of high-altitude water vapor, and if so, find out where it was coming from. The most thorough way to go about this will be to examine both today’s snapshot on the Weather Map and the 5-day animated trails of precipitable water found at the site featured in yesterday’s letter.
The next map immediately tells us that a relatively large amount of water vapor has indeed entered the region. We are also quickly made aware of how well-connected the region is to areas well to the south and west that are known to have volumes of warm water available that can provide unending supplies of new evaporation. These vapors still have to travel a long way, several thousand miles in some cases, in a limited amount of time, in order to arrive at the destination area in a reasonably undiminished state. While this map by itself doesn’t prove anything, I think its fair to surmise that when we see so much vapor in the destination area it could not have come from local sources or any close-by neighboring waters. It must have originated in places having far more evaporation potential, and would then need to find an expeditious means of transportation that could take cohesive batches of vapor as far as northern Siberia and the Arctic Ocean—no small thing to accomplish. Rapid, high-altitude wind transport is probably the only practical solution that is even possible for doing such a job.
The investigation continues by seeking out the possible sources of vapor, without setting tight limits on distance that must be traveled, requiring only that movement must come from the west while sloping northward because there is no other option (in the NH) for making use of the high-altitude wind system. The above map offers a long list of prospects, so let’s go ahead and name them. Starting from a point farthest to the west, waters in the Gulf of Mexico, Caribbean Sea, western North Atlantic and maybe even a bit of the Pacific Ocean west of Mexico all appear to converge into a strong stream that leaves vapor footprints stretching far to the north and east, but look like they fall short of the mark. The eastern North Atlantic, which provides two small streams heading directly into Europe, looks better, and these are soon combined with streams of varying strength emerging from west Africa’s rainforest, the Mediterranean Sea, the Red Sea, the Persian Gulf and possibly some northwestern parts of the Indian Ocean. This entire group appears to have merged into one big stream when passing away from Europe and heading directly toward Siberia, thence surely providing the bulk of its vapor increase.
With that picture in mind I went over to the animated website to look for tracks. There are plenty of them, all headed in the right direction, but there are also a lot of irregularities as streams break down and outgas, recombine with other fragments, break down again and so on, not a very smooth operation. It finally ends with widespread vapor coverage having mixed bits of concentration in a range of 15-25kg. I don’t know what the true historical norm would be for northern Siberia and surroundings on this day but feel pretty certain it is considerably less than that. Also, note that I have made no reference to jetstream activity for this project, just letting the vapor streams do their best and speak for themselves—which worked out fine on this occasion and makes the task a whole lot easier.
Carl