The tremendous swath of warmth spanning an area from California to Great Lakes shall shift eastwards as we close the books on November and begin December.

November has very much been categorised by a cold north, warm south which La Ninas tend to favour.

Thanks to strong high latitude blocking, a warm US doesn’t typically hold and models do see a dramatic flip between December warm open and likely cold middle.

Note the big flip from widespread well above normal to below normal in the 11-15.

CFSv2 weeklies show the flip nicely.

Confidence is growing fast due to the strength of the -AO/NAO signal and projected weakening of the polar vortex.