The U.S. gas population weight HDD forecast shifts warmer to the 10-year normal next week and warmer than the 10-year normal for mid-December. Consensus of the CFS V2 and ECM indicates HDD recovery to normal national heating demand by January 1st. The January 3-9 HDD forecast stays interesting as ECM maintains normal demand and CFS V2 is cold again.

In 16 days (Dec. 18) the GFS indicates a very cold stratosphere in the polar region. A classic stratospheric warming event causing mid-latitude arctic air outbreaks would be just the opposite of the forecast. There is some stratospheric warming across Asia in 16 days possibly inspiring some arctic air across parts of Russia to Tibet.

The Great Lakes are exceptionally warm, averaging in the upper 40’s to low 50’s and with a steady arctic air mass crossing over the lakes an immense lake-effect snowfall event is underway. The 1-5-day GFS snowfall forecast indicates an extreme amount from Western Michigan to New York with widening southern extent due to Alberta Clipper storms in the 6-10-day period.

The rainfall across parts of Brazil and Bolivia has been in the 4-8-inch range during the past week. Aerial coverage of the wet weather pattern is immense and includes most of Brazil (except northern areas) and Argentina (except western areas). Interestingly, the rainfall occurs during the subsidence phase (across the America tropics) of the Madden Julian oscillation (MJO) which normally inspires a drier South America climate.