After a frigid start to December, the month finishes very warm. Consequently, cold U.S. population weight HDD projections for DEC-25 from earlier this month are revised sharply warmer. The JAN/FEB-26 forecast remains close to the 10-year normal. In Europe, colder weather arriving in late December takes the edge off the previously mild pattern for early meteorological winter while the incoming cold is sufficiently lengthy in duration to cause a colder mid-winter revision.

Utilizing all operational models, forecasts are agreeable to the decelerating warm pattern to near the 10-year normal for next week. In the Jan. 2-8 period, forecast models vary widely from a milder national scenario (GFS ENS/GFS) to much colder than normal (CMC ENS/ECM). The just released GFS was near the overnight consensus.

Natural gas prices spiked to $5.46 on December 5th anticipating a frigid East U.S. 6-10-day period. Arctic air was widespread across most of the eastern half of the U.S. The PJM System (Chicago to Washington) average temperature was a frigid 18F on December 14-15. Typical of arctic air presence when snow cover is minimal, a following warm-up is easier to generate. By December 18th the high populace PJM sector warmed above normal.

Deep upper trough forms over Eastern Europe during late December. The result is a significant cold. Arctic air gathers over Northwest Russia and some of that air mass is pulled into Europe. A vigorous storm track across the Mediterranean Sea with the northern portion all snow including Southeast Europe, The Black Sea region, and Southwest Russia.