There is a substantial warm anomaly in the west/central part of North America today, closely walled off on two sides by equally strong cold anomalies.. The principal factors of cause behind this situation should be of interest.
The source of the added warmth is not hard to spot. On this Precipitable Water map I see two sizable vapor streams heading for the western coast, with the larger one emerging from the Pacific and the smaller from an area closer to the continent. This map also clearly reveals a sharp border between the large area where water vapor is relatively abundant and regions to its north and east that are much drier. Notice how this border closely matches the border in the first map that separates the warm and cold anomalies. As I see things, the difference in nearby temperature anomalies, cold versus hot, is about 15 degrees. The difference in corresponding PWat readings is something like 4 to 12kg, also cold to hot and just for ones close by, making the warm areas more than twice as “wet” as the cold ones. This one measure can fully account for the magnitude of the difference in actual air temperatures, as reflected in their differing temperature anomalies. Both sides that are so near together would normally have about the same temperature and same total humidity on this day, somewhere in between these two extremes.
Could a long and powerful jetstream pattern be involved in setting things up this way? Absolutely, as we see here:
Did the jetstream wind and the vapor stream interact by producing rain as both were moving to the north and east in close proximity? Yes, indeed, and the rain was heavy. This is a common occurrence whenever the jet wind is angling poleward. Further, we can see that not all of the vapor that has been picked up and held by the jet is being consumed in this manner. A fairly large amount survives as vapor and ultimately takes off on its own, along with its greenhouse powers. Also, a good part of the original vapor stream was never picked up at all by the jet but stayed off to the side while advancing in air that was almost perfectly clear from start to finish.
One more image will reveal the reason why a strong jetstream happened to be located in this particular spot, where it could successfully block a massive vapor stream from moving any farther to the north. The other side of the Arctic Ocean, where things are much warmer, is not so well protected at this time.
Carl