Strong upper-level low pressure rests on the Southeast Brazil Coast next week and is positioned to unload significant rain on East/Northeast Brazil with the western edge of the wet weather pattern reaching Central Brazil. No rain is forecast for Northeast Argentina to Southeast Brazil.

The U.S. gas population weight HDD forecast certainly identifies the increasing heating demand. Utilizing all models, the HDD forecast consensus through mid-January is colder than yesterday and trend colder for the second half of January into early February according to CFS V2/ECM consensus. The longer duration cold will occur if snow cover expansion is sustained late in January.

Overnight, the U.S. gas population weight HDD forecast for Jan. 3-9 was revised colder by ALL models (except GFS). During Jan. 10-16, U.S. heating demand settles to the 30-year normal. The extended range HDD forecasts for the second half of January are near to below normal. Consequently, Jan. 3-9 is the coldest week of mid-winter.

In a new twist, ECM is forecasting a cold stratosphere across the polar region and eastern North America in the 11-15-day period. Elusive stratospheric warming shifts to Eurasia. Beneath the cold stratosphere, GFS indicates a mild ridge pattern in the East U.S. instead of an evolving polar vortex pattern as previously reported.