Much of the Eastern US has returned to normal and below normal levels over the past week or so. After over 1 month of very mild weather, the pattern has finally changed. We have progressed into a pattern where there is a ridge over the West and a trough over the East. This mean that air from Canada is allowed to dip down into the Eastern US and keep us around normal readings, with occasional shots of cold air bringing many below normal. Well, it is going to get VERY cold in the Eastern 2/3rds of the country. By January 30 (plus or minus a few days) the polar vortex will move over the near Hudson Bay. What does this mean? This means we will develop a transpolar flow where air from Siberia flows across the North Pole, into Canada, and into the US. This means that by the end of this month/beginning of Febuary, many places will have extremely cold weather. With below normal levels of snow pack in the Northeast, the air probably will not be record breaking in most areas, but it will be very cold. Many places in the Northeast will see highs in the single digits to middle teens. The Midwest could see highs ranging from 0F to around -20F, depending on where you live. Lows could easily go as low as -60F in a few cold spots. Here is a computer model that shows what I am talking about. The yellow, orange, and red areas are temperatures WELL below zero. Overall, this looks like a very cold airmass that could break records in many places of the US.
I got this from a friend on a CP forum http://www.terraforums.com/forums/showthread.php?t=106784