The US has largely avoided any sustained cold weather during the month of December and accumulating snow has been quite sparse. At the same time, several regions around the world have suffered through some serious cold spells with snow including in much of Europe, Asia, western Canada and Alaska. The overall weather pattern here in the US will indeed undergo some changes over the next couple of weeks that will bring some fresh Arctic cold and accumulating snow to many sections beginning as early as this weekend to the Rockies, Northern Plains and Great Lakes, and eventually, signs point to cold and perhaps snow reaching the Northeast during the second half of December.
One of the indexes we closely monitor during the winter season here at thesiweather.com is the North Atlantic Oscillation (NAO) since it can sometimes be a leading indicator for pattern changes in the Northeast US, and it appears that this index will soon drop sharply into negative territory which often leads to more sustained cold air outbreaks in this part of the country. There are even some very early signs for a storm to arrive into the East early in the week after next, at the same time there will likely be cold air around. All of this will be closely monitored over the next several days and gives some hope for those that wish for a white Christmas.