MJO avoiding the warmer phases thus far, some have it looping around toward the better phases from the circle last week of December.
This is noticeably different than last year which had it going through 4-6 and lingering there for weeks.
This could be why a -AO/neutral NAO are showing up 2nd half of December. Personally I'm a fan of this progression and it's why January could be a surprisingly good month.