Part 7/12:
A key aspect of this forecast is the expected negative North Atlantic Oscillation (NAO) pattern, which fosters a blocking high-pressure system over the northern Atlantic. This pattern effectively allows Arctic air to plunge into the eastern and central U.S. more easily. As the pattern evolves into a neutral or positive NAO, the cold air mass will shift westward, bringing additional winter conditions to the western U.S., especially from mid to late November.
This oscillation greatly influences regional weather—where the coldest air is, snow is most likely to accumulate, and where unseasonably warm or cold conditions will prevail.