Pattern changes are notoriously difficult to accurately predict — especially more than a week in advance. This is part of the reason for caution when you come across any specific predictions for snowstorms or intense cold snaps more than a few days in advance.
“Models tend to prematurely predict pattern changes, and I think that this is a good example of that,” wrote Judah Cohen, director of seasonal forecasting at Atmospheric and Environmental Research, in a text message.
Cohen noted that Europe responds more quickly to the negative phase of the NAO compared with the eastern United States. In that sense, he expects cold air to continue to affect Europe before taking aim at the Lower 48.
As for the chances for significant snow in the eastern United States, Cohen said that “the payoff usually comes at the end of the pattern.” He added, “The best chance for a big snowfall is when the NAO is transitioning from negative to positive.”
The Mid-Atlantic and Northeast still appear on track to turn more wintry during the second half of the month. As Christmas approaches, if you’re rooting for snow, waiting is often the hardest part.