Big shift in GFS from 06Z to 12Z from d3 to end of run. Now looking very similar to 0Z Euro, with HP over GIS merging with HP over CAA to form ridge that intensifies from d3-8, shifting to CAB and topping out well over 1035 hPa by d8. I'm looking forward to seeing the 12Z Euro to see if it corroborates. Also comes with pretty concerning WAA plop over the pole d6-8. This would make for a helluva week ahead!
Regarding 2020 staying "within the pack" in regard to area, extent and volume, I agree that it hasn't strongly distinguished itself from the top 7 years with regard to these general metrics. Yet what's far more concerning for me is the record-breaking regional changes, especially the recent onslaught of ice in the CAA. From my perspective, the snow and sea ice there serve as a mitigating factor to WAA over the thick MYI that builds up against the north CAA and Greenland. Losing the CAA ice early in the season seems like it would make the thick MYI much more vulnerable late in the season, as well as creating open water that does not normally occur in this area during peak insolation (impacting the following freezing season). Similarly, the loss off the fast ice in the Laptev and ESS diminishes its ability to curtail warm air coming off Siberia, though the adjacent ice melts out most recent years. Until the past couple of weeks, I was thinking the Siberian anomalies might badly precondition that side of the arctic for next freezing season, but not threaten the thick ice in the CAB. Now it seems like the assault might come from all sides except the Beaufort/Chukchi, and directly threaten the thick ice later in the season.
I'm curious to hear what the veterans have to say on this. I've been lurking since 2015, but don't have a very longitudinal perspective on this, only started to become familiar with most of this content in the past couple years.
Edit: Climate Reanalyzer now shows the 12Z GFS CAB HP topping out at 1039 hPa at +186h (!!!)