The high correlation between temperatures at various levels in the lower half of the atmosphere is clearly evident, and it's also plain that the PDO has a strong connection to temperatures even up at 500 mb (~18000 feet). Here are the Pearson correlation coefficients between the November-December PDO index and temperature:
850 mb: +0.72
700 mb: +0.67
500 mb: +0.50
Interestingly the correlations are slightly higher at 850 and 700 mb than at the surface, and the correlation remains a fairly robust +0.50 at 500 mb.
The deep and coherent nature of the warm air over Fairbanks since the start of winter is illustrated by a time-height cross-section of temperature anomalies for the lowest 3000 m (see below). It's clear that the recent cold spell at the surface was a very shallow phenomenon; warmth continues unabated aloft. In fact, temperatures have warmed dramatically again in the past 24 hours, and this afternoon's balloon sounding reported a temperature of +7.6 °C at 850 mb, which is 19.2 °C above normal. This is just about the greatest warm anomaly seen so far this winter at 850 mb (+19.8 °C was seen in November).