By late Saturday, a very cold air mass will be centered over the southeastern interior, with predicted 850mb temperatures below -35°C. That's seriously cold.
An 850mb temperature of -35°C hasn't been observed in Fairbanks since 1999, although late January 2012 came very close. However, it looks like the core of the cold will miss Fairbanks, so -30°C or so seems more likely on the Fairbanks sounding.
Cold at valley-level will be severe, but just how bad will depend on winds and cloud cover, as usual. Widespread -40s seem likely, and given the location of the cold core I wouldn't be at all surprised to see -60°F at Chicken. The last -65°F at Chicken was in 2009.
Speaking of cold, it's worth noting that southeastern Alaska has already been experiencing the cold side of the flow pattern in recent weeks, even while extraordinary warmth has occurred elsewhere in the state. Ketchikan dropped to 0°F and saw two back-to-back days with high temperatures below 20°F; both of these feats were last achieved in 2012.