After a brief bout of unsettled weather, New England is turning back to a mostly dry pattern once again. An area of low pressure will continue to swirl well to the northwest of New England, near James Bay in Canada. This low pressure system will keep New England under broad cyclonic flow for Saturday, though only limited snow showers are expected this afternoon across far northern New England. The rest will likely just see some cloud development in the afternoon, similar to Friday.
This cold cyclonic flow will help a major lake-effect snow event develop for the eastern shorelines of Lakes Erie and Ontario, where several feet of snow will be possible through the weekend. Between 20 and 30 inches has already been reported in the Erie, Pennsylvania area. In New England, only light snow showers are expected with little to no accumulations across the northern woods.
New England, and really the United States as a whole, will be entering into a rather stagnant pattern for the first half of December. This pattern is a ridge-in-the-west-trough-in-the-east. This will lead to several days of persistent weather with very little variation between them. Without any well-defined storm systems within the troughing over New England, the region will be mainly dry (outside of occasional mountain snow showers) and partly cloudy to mostly sunny, with generally more clouds farther north.
This pattern will also result in a persistently cold air mass over the northeast. High temperatures in the 30s will dominate much of New England for the next week with overnight lows in the teens to low 20s. Persistent troughing will allow for multiple shots of polar air across the eastern United States through midweek. This will allow temperatures to drop a degree or two each day through mid-week, which may be the most variation in the day to day weather in this strong-holding pattern.
This will be a prolonged stretch of colder than average weather, which will buck the trend seen for much of the fall. The fall saw very brief 1-2 day cool-downs followed by prolonged stretches of warmer weather. These colder temperatures are expected to last through the first half of December. The Climate Prediction Center gives New England a 60-80% chance of below average temperatures through December 13th. In the shorter term, much of New England has an 80-90% chance of below average temperatures next week, which will be discussed further below.
The most organized weather system in this trough next week will come around Wednesday to Thursday. An Alberta Clipper-type system is looking poised to drop out of Alberta (hence the name) and quickly scoot across southern Canada and into northern New England. These kinds of systems tend to be quick-hitting, minor snowfall events for the region. This one appears to be no exception with low probabilities of more than three inches of snow.
Below: Current weather map for Thursday morning showing the Alberta Clipper system approaching:
A strong cold front currently looks poised to follow the Alberta Clipper, which will open the door for a colder air mass than the one that will be persistently over the region through midweek. There are indications that New England may get its first taste of an Arctic air mass of the season around next weekend (December 6-8). Currently, next Saturday appears to be the coldest day, when highs may top out no higher than the 20s for much of the region. Only time will tell exactly how cold it will be able to get (specific temperatures/wind chills).
Below: Euro showing temperatures at the 850mb level (about 4,700 feet above sea level) next weekend, showing the potential for a frigid air mass to move over New England. Time will tell how cold it gets at the surface:
Looking into the long term, there are indications that a slow breakdown of this persistent pattern will occur through the second half of December. This would allow for a warm-up (relative to averages) heading toward the end of the year as the western ridge slowly breaks down and potentially more zonal flow sets up. This is looking into the long term, so only time will tell how this all plays out.
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