My PIPS-based June ice extent forecast minimum (dashed line) was off by 11%. Starting in mid-August, persistent winds blew from the south – pushing the ice edge back and melting out the thinner ice.

Once the winds stopped, that same region of missing ice quickly refroze, and brought the ice back to where I expected it to be.

Conclusions:

1. US Navy PIPS is an excellent indicator of ice conditions.

2. Variations in wind from year to year largely determine the relative minimum extent rankings of recent years. The rankings have little to do with the actual condition of the ice.