It seems pretty clear that the much anticipated arrival of winter-like weather will come in 2 stages with a break in between. Stage 1 arrives on Thursday after a storm passes by to the northeast and tugs down cold air from Canada. 850mb temperatures drop below -8c across Connecticut and below -10c across portions of Vermont. Friday and Saturday will feature highs in the 40s for the valleys and 30s for the mountains up north with some great snow making weather at night. As the change is being ushered in I wouldn’t be surprised to see some accumulating snow in the higher elevations of central Vermont on Thursday with an upslope component to the wind and some wrap around moisture. I’ve included a “very low” probability for 2″-4″ of snow on the Powder Potential forecast because of this.
Behind cold shot #1 we will see a break and a brief warm up. The intensity of the warmth is uncertain and depends on the strength and track of a low pressure system to our west. It seems likely that temperatures will go above normal for a period of time between Monday 11/22 and Wednesday 11/24. This is all because the weather patten is changing drastically across the northern hemisphere. The first thing showing up is a huge blocking ridge in the Gulf of Alaska that will dump cold down the west coast. In response to the trough over the west the atmosphere responds by building a ridge of high pressure in the southeast that promotes a surge of warmth into New England.
This is a composite of the Monday-Wednesday time frame on the 00z GFS and European models and you can see the cold height anomalies to the west and warm anomalies to the east. What also shows up is a mammoth -NAO block over Greenland. The cold air dump looks like it will first get established out west and eventually migrate east as the -NAO promotes cold, troughy, stormy weather over the northeast. The first cold shot should be in by Thanksgiving and it could last for a week or longer depending on how strong and persistent the -NAO is.
So get ready for some cold and probably a little bit of snow too. It will take some time to get here but the details seem to be slowly becoming more clear.