Fig. 1: The GFS ENS 8-14-day temperature anomaly forecast for North America and Europe.
Discussion: Pattern change is ahead in Europe next week as the short-term mild climate reverses colder in the 6-10-day period with possible arctic air into Eastern Europe days 11-15 (Fig. 1). The European cold locks-in through early January. Meanwhile in the U.S. the warm pattern south of snow cover continues. However, if snow cover across the northern states increases (which is very possible) the increasing Canadian chill could ease farther south. Already from Washington to northern Minnesota looks very cold and New England is trending colder in the 8-14-day period. The double-whammy cold for parts of the U.S. and all of Europe is monitored for potential significant heating demand.
The U.S. daily HDD shifts from very warm this week to normally cold the last third of December with potential for a colder result the last week of December (Fig. 2). The Europe HDD demand is also below normal for this week but shifts much colder and somewhat larger demand than normal for the last third of December (Fig. 3).
Fig. 2: All models and their daily national HDD forecast compared to the 10-year and 30-year climatology for the U.S.
Fig. 3: All models and their daily national HDD forecast compared to the 10-year and 30-year climatology for Europe.