Cannot recall last time I have seen such a cold anomaly forecast across almost entire USA.

Neither can I, have a look:

UPDATE: This map from Dr. Ryan Maue of WeatherBell shows that over 75% of the USA will be below freezing for overnight lows on December 8th:

Dr. Maue writes:

CONUS average low temp of 17°F for Dec 8th according to ECMWF 12z is exceptionally cold — there will surely be record lows.