Today, instead of just talking about the Weather Maps and how great they are I had better produce some evidence. This is a good day to show how close the interconnections are between different maps. No fewer than eight different maps will be involved, each of them related to all of the others either directly or indirectly. I am going to begin with one that is unusual, Sea Surface Temperature Anomaly, because it literally helps to explain why current air temperatures over Greenland have reached such an extreme high level for this time of year:
The anomaly in much of the Caribbean is about 1C, while parts of the Gulf, the Florida coastline and Eastern seaboard have spots running several degrees warmer than that (use magnification), for reasons I am unable to illustrate. These anomalies all help to bring water temperatures up to the levels required for providing enough energy to lift new streams of evaporation upward as much as three miles, where the upper level of the troposphere and its changes in wind system are established. The extent of needed sea surface temperatures (at least 24-25C) are plainly visible on this next map:
Waters in the Pacific directly to the west also match these temperatures and can contribute more high-level vapor in the same way. Having skies free of low-level clouds is another aid to efficient vapor uplift, and we can see a widespread abundance of totally clear skies over these warm waters on the next map. All such skies must be loaded with vapors from constant evaporation, and vapors added must keep moving, with no hesitation, in order to stay out of the way of those that follow:
What happens to these vapor streams when they reach the upper level of the troposphere and its own special type of winds? I see them getting swept up by any fast-moving jetstream winds that happen to be passing by, normally from the west or southwest at this latitude. Today we see one in just the right place, ready to do the job. The vapor streams never need to stop moving, and are likely to stay with the jet as long as it keeps blowing toward the east and north. This stream will soon begin to do some shifting, merging and splitting that will affect the vapors it carries in a variety of ways. The map just above shows how vapor condensation and drenching precipitation begin naturally, and continue thereafter, as soon as the air and water streams come together.
Jetstreams do not have these positions or make these moves by accident They are governed by forces that are generated by the shaping of air pressure patterns unique to the upper part of the troposphere. You can see a truly vivid demonstration of the way wind pathways exactly match the lines of air pressure change in the Greenland area by studying those lines on this next map:
Now it’s time to actually display what began as water vapor streams that were picked up by the jetstreams, then quickly transformed into precipitable water (PW) streams in order to acknowledge the act of condensation startup. Matching the movement of PW streams and jetstreams does have complexities, but in this example the basic correspondence is displayed with ultra clarity as the point where they make their move together in the direction of Greenland, which was our original objective:
Notice how the relatively high PW values stretch all the way across the north Atlantic from one continent to the other. That will prompt us to take a quick look at the Air Temperature Anomaly map in search of an outcome, which is even warmer than expected over the surface of a region that is entirely oceanic:
The really special interest derived from this image is the outcome for Greenland itself, which gained an extremely warm anomaly, compared with the adjacent extreme cold anomalies covering a large part of northern Canada. The latter happens to be much lower in elevation and also more to the south, which means normally much warmer. The difference in actual temperatures, which helps to explain why there is so much contrast in the anomalies, is revealed in this map—finally, the last of eight!:
Why is there so much difference? Because Greenland happened to be in the way of that massive PW movement while northern Canada stayed just off to the side of it. Actual amounts of PW involved is exceedingly small in both places, but can be observed and interpreted. Greenland was able to raise its daily average input, or “daily dose,” from something under 1kg to something well over but still under 2, which is enough for a full double. Any double on any one day is worth an added 10C in temperature, just as we see recorded in the anomaly. In Arctic Canada the numbers are the same, but in reverse directions. Use magnification and look closely to see the current PW shadings and to get all of the temperature numbers just right. I hope you are in agreement with me about the extraordinary value of these maps.
Carl