Hopefully, I have found a way to preserve intact weather map images for more than one day, but won’t feel secure until tomorrow. There are images today that need to be recorded and kept as an ensemble, helping tell more of the story of the long-duration Arctic polar zone heatwave. Today’s map shows how it is undiminished in size and strength, and also appears to indicate other locations that might be affected by the same sources of heat because of their proximity.
Before I open the Precipitable Water map, there is one little detail in the Anomaly map that requires attention—a short little finger of approximately 10-degree warming that ends right at the edge of the pole itself. There is a little spike of vapor concentration on the next map that will match up perfectly in position. The spike is carrying 3 to 4kg of total Pwat over a spot that normally would be less than 2kg at this time, thereby providing just enough extra energy to cause the 10C temperature boost. More generally, this map provides a good look at how four major vapor streams (one barely visible) are in the process of progressing from their tropical sources toward the polar zone. The one situated to the east of Greenland and producing the little spike is making the most overall headway at this time, and is also a real giant of durability by any standard.
A different map shows this last relationship in better perspective. In fact, when you get close to this image you can that all of these streams are contributing at least a small amount of extra vapor deeply into the warm zone. Note how the dominant stream is collecting most of its vapor from sources all around the corner of the Atlantic that includes the Caribbean Sea. There is an abundance of warm surface water in that area that cannot stop evaporating and is not covered by low clouds, facilitating a massive amount of vapor admission into the upper level wind system that will remain its home for one or more days to come.
The journey this vapor will take, with a small part of it ending up by warming air the pole itself, is certainly worthy of scientific interest, and always sure to involve jetstream winds as the journey proceeds. I can offer a few ideas about how the winds affect this particular stream.
What I am seeing on the above maps is that the original vapor stream is being split into two parts. The eastern part is steered away from going northward by the jet wind but can still follow along its outer edge all the way to Europe—which quite notably sees a lot of warming as a result. There it finds a break that some of it can pass through and continue on northward with little resistance. The western part gets trapped in the broad underbelly of the of the passing jet and is thereby swept directly north as a passenger. A good share of this vapor condenses and rains out on that journey, but not all. When the jet wind abruptly makes a sharp bend to the right a small amount of vapor just spills out into the vacant area above and keeps going from there. While no longer concentrated into a stream the fragments are still able to do some regional warming around Greenland.
One more image is useful mainly because it shows how much vapor was indeed rained out by the wide jet as it headed straight north, letting us appreciate the great volume of new evaporation being accumulated when conditions are just right. Give credit to all of that cloudless sky, which would stay even more clear without the jetstream contacts. The vapor stream that stayed on an easterly course at the outer edge of the jet interacted with it just enough to leave a long trail of light rain but otherwise held on to a vast amount of its original content even as it moved beyond Europe.
Carl