January was a shit show... +NAO, West-biased PNA and strong PAC jet just acting to pin the entirety of the hemispheric reservoir of cold over in Siberia and pin a trough on the west coast. Good example of how index values can be misleading. Yes, PNA was positive, but being centered off of west coast rendered it basically an RNA. Yea, AO was negative, but without any poleward Aleutian ridging to tap Siberia, all it did was pool the cold over there. Northern tier of the US probably would have been better off with a +AO.