Days 6-10/11-15 commentary: Cold air retreat is in the forecast. The cold pattern hangs on across snow cover days 6-10 near and north of the U.S./Canada border. However, the Gulf of Alaska low becomes strong days 8-14/11-15 causing a mild Pacific influence across the U.S.
Days 16-20 commentary: A warm pattern across the U.S. Canada is trending colder.
Commentary: Arctic air production caused by stratospheric warming is marginally in-place for another week or so followed by a stratospheric cooling event days 8-14 which will shut off production.
Commentary: Although snow cover has expanded the last couple days in the eastern U.S. the month of December produced below normal snow cover for the U.S. The northern hemisphere was also slightly below normal snow cover in December. Canada was most snowy.