The Deepening Night

Daily solar heating is decreasing rapidly now, and the effects of less daytime heating and longer nights are showing: it's almost getting (briefly) dark now. This is being accentuated by high pressure aloft, which is keeping skies mostly clear over the Interior: below is the 500mb analysis for 4am ADT Friday from Environment Canada, showing the elongated high centered about at 63N.

Updated Friday morning low temperatures in Fairbanks-land show a substantial nocturnal inversion and include:
Angel Creek RAWS: 28F
Goldstream Creek: 29F
Woodsmoke PWS: 32F (near North Pole)
UAF West Ridge: 39F
Eielson AFB: 39F
Fairbanks Airport: 42F
Keystone Ridge: 47F
Clearly Summit: 49F
Nenana Hills RWIS: 51F