The 7-day rainfall observations across South America were aggressively wet in Northern Argentina including Paraguay while East Brazil was extremely dry.

Short-term hazards are intense and feature Blizzard Warnings across the Upper Midwest to the Northern Great Lakes and widespread high wind alerts for the East-central and Midwest U.S. Winter Weather Advisories for snow to ice extend across the Northeast States.

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.