I learned something today that is worth knowing about by anyone who has decided to pursue a close study of high-altitude vapor stream movement. When you find a warm anomaly and the corresponding batch of water vapor serving as the probable cause, and observe that the vapor is a very long distance away from any possible source, it is often not clear about how to identify that source. The long stream images that we see every day have almost always changed from the day before, and again from the day before that, and so on. So any spot far along the stream that you are looking at today may very well have a past history quite unlike anything that is showing today. Nearly all streams usually do not maintain a regular stream bed but keep shifting in shape and direction of movement almost every day. Mergers with other streams, as well as divisions, are not uncommon.
There is an easy way to resolve this issue. Pick out a batch of vapor that seems to have come to the end of the line, keep the location in mind, and transfer your view over to the animation website at http://tropic.ssec.wisc.edu/real-time/mtpw2/product.php. Run the five-day movement a couple of times and then stop it just short of the end. Now run it in reverse, which you can only do one click at a time on a special button. The result might be a complete surprise. For an example, look at this next image, where one can spot an advancing stream with bright blue shading that ends with a brown T-shaped umbrella close to the top of the map. Can you guess where the batch of vapor that now makes up the T came from originally?
By using the animated reversal technique I soon found out that a great deal of mixing has been going on every day for five days, with considerable contributions sweeping in from the Siberian plains directly to the west. The large, bright blue area below the T is the result of multiple mixing from many directions that has also been going on for days and is now leaving its own mark on the anomaly map. More vapors that you can see today, moving in from the south or stretching off to the east, mostly shaded in dark brown, are strong enough to produce current warm anomalies of a milder sort. All of these are displayed on this map, and all provide evidence of the unique powers of high-altitude water vapor:
The entire long string of warm anomalies running thousands of miles from north to south in this case represents a mosaic of bits and pieces that appear to have separated away from streams that have originated over broad areas of ocean water. Sometimes when small vapor streams merge in a forceful way they are able to produce light rainfall from very thin high clouds. It is possible to pick up and analyze some of these events by going to the Windy website at https://www.windy.com/-Show—add-more-layers/overlays?ptype,64.359,121.992,3,m:fsYaiJQ—which is set here on one of the special links that are generally useful for analyzing specialized cloud formation and behavior exclusive to extreme altitudes. Don’t overlook the link that shows the altitude of cloud tops. The amount of detailed data this site provides is just incredible!
Carl