The first sign of the changing season is upon us. I have been watching with much interest, the cold building in northern Canada. The GFS has continued to show this cold building, slowly, but surely in the northern reaches of Canada. Basically, this cold is farther north than where many actually live. Its the first sign of the cooling northernmost part of our planet. Daylight is slowly dwindling in the northern hemisphere.
Don't worry about this cold, however. These are the 850mb temperatures for later on in the month. As you can see, the lower 48 and even much of southern Canada will still be seeing extreme summertime heat with temperatures in the 90's and 100's. Summertime heat will be all over the Lower 48 and even Alaska will be seeing above normal to normal temperatures. However, look how expansive the temperatures below 0 degrees (C) there are and how it is not blotty. The cold is slowly starting to spill over from the North Pole and sea temperatures up there will cool and ice will start to thicken. That is a good thing in establishing a cold source, almost like a refrigerator, for the fall months, September and especially October, November, and early December. This will allow cold to come farther south, earlier rather than later.
There are many other factors at play here, so we are not absolutely sure of cold coming in the next few months, but cold building up in those northern lattitudes are a good sign. We still have got a lot of summer weather to get through before we even have to worry about the cold building way up there.