All indications continue to support the idea of a significant temperature pattern change here in the northeastern US beginning late this week. One of the contributing factors is the still unfolding stratospheric warming event that is occurring near the North Pole. In a dramatic turnaround, the stratospheric temperatures over the North Pole region are forecasted to completely flip from their cold levels in mid-December to much warmer levels in about a week or so. Historically, these polar stratospheric warming events have often led to the formation of a blocking pattern in the upper atmosphere over the Arctic region. That Arctic blocking would likely, in turn, produce numerous cold air intrusions into the central and northeastern US from mid-month on, and these cold air outbreaks would be much more sustainable compared to recent weeks which have seen only quick shots of cold air. In addition to the polar events, La Nina has undergone dramatic weakening in recent days in the eastern tropical Pacific Ocean. Several winters that have featured a wintertime transition from a weak La Nina to a neutral or El Nino signal have seen a considerable uptick in snowfall during the latter part of the winter. Finally, the potential “pattern-changing” cold frontal passage on Friday that will be leading winter’s comeback may very well be quite interesting in itself with snow showers and strong wind gusts. There may even be a burst of snow early enough in the morning to possibly affect the Friday morning rush hour. Stay tuned.