Melting all of that arctic sea ice and permafrost has an effect. It takes a lot of heat to fully melt snow and ice…we see it up here in the spring when we’re waiting to warm up. It doesn’t efficiently warm until you thaw and dry out. Now we see that line in the arctic expanding northward during the summers. The summer cP airmasses become warmer and it’s more difficult to drive them southward. Tippy’s Hadley cell expanding northward doesn’t help either. It just results in more of a lag in cool season climo.
CON’s avg first freeze in the 51-80 normals was 9/22. In the current 91-20 normals it is 10/3.