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.

An early season exercise in snowfall forecasting is offered by the emerging colder weather pattern shifting into the East and the interpretation by the GFS, ECM, and AIFS. Thanksgiving Day looks snowy as cold air filtering into a frontal zone stretched across central and southern New England yields a swath of day-long snow accumulating to 4-8 in. according to GFS.