A storm system will traverse the Midwest Tuesday night before moving into the Ohio Valley. This will support a surface low pressure system to form near the Mid-Atlantic. This coastal low will then track across southern New England into the Gulf of Maine. The system is poised to track well inside the benchmark, bringing a soaking rain to southern New England with a period of mixing and snowfall across interior portions of northern New England.
ALERTS (as Tuesday morning)
Winter weather alerts will likely expand into northern New Hampshire and Maine later today. Wind alerts will be possible across New England for both Wednesday and Thursday.
TIMING
As the primary low passes to the west of New England this evening, it will send an initial round of rain from southwest to northeast, likely beginning just before midnight for Connecticut (it'll be another wet New Year's Eve in Times Square) and continuing to steadily move northward through sunrise, making it into western Maine. As this band of rainfall makes it into the higher elevations of New Hampshire and Vermont, it will quickly changeover to snow.
Below: NAM showing potential weather early Wednesday morning (1st image) and around sunrise Wednesday (2nd image):
As the parent low pressure system continues to move northeast around the Great Lakes, a secondary, coastal low will form near the Mid-Atlantic coast. This will strengthen and become the primary low. This low will track well inside the benchmark, likely across Rhode Island and the South Shore before entering the Gulf of Maine. This track is ideal for a soaking rain across southern New England and the northern coastal plain with a shot of snow for interior northern New England.
By the early afternoon, the storm will likely have lifted into the Gulf of Maine, continuing to strengthen. This will keep widespread rain and snow ongoing across much of northern New England while southern New England gets into a dry slot on the south side of the system. It likely won't be completely dry all afternoon long with isolated to scattered showers continuing to pop up, but it won't continue as steadily or as widespread as the morning.
Below: NAM showing potential weather early Wednesday afternoon:
As the storm pulls northeast into Maine, it will slow down due to a large area of high pressure to the south of Greenland, preventing a timely departure. This slowdown will allow for continued snow to fall across the northern third of New England through the day Wednesday and into Wednesday night.
Through Wednesday night and into Thursday morning, snowfall will become more elevation based. Depending on the exact position of the low on Thursday morning (which is currently forecast to be just north and east of Maine), snow may re-blossom over eastern Maine with continued snow showers in the Green and White Mountains through Thursday. This could end up as a 36-48 hour snow event for the northern third of New England (and all of the higher terrain) while southern areas and lower elevations see an 18-24 hour event.
Below: NAM showing potential weather around sunrise Thursday morning (1st image) and early Thursday afternoon (2nd image):
SNOWFALL
Total snowfall amounts will very likely be highly terrain based, with mountain slopes and summits coming away with much more than valley floors. The surface low's track across southeast New England into the Gulf of Maine is usually an ideal track for a widespread snowstorm across interior northern New England, the main issue is that there will be no cold air in place ahead of the storm. There just isn't enough time for cold air advection with this storm following so closely behind our last system on Monday.
Without that cold air in place, the storm will need to produce its own cold air with heavy precipitation rates. With a strengthening storm slowly moving across New England, that will likely happen for northern areas. By Wednesday morning, snowfall rates of 1-2 inches an hour will be possible for a time across higher elevations, leading to a quick accumulation. Persistent snow on the backside of the system through Thursday could add several additional inches of snow for the Green and White Mountains as well as eastern Maine.
When all is said and done, this will almost act as a springtime storm, with the jackpot zones across the higher terrain with much less across the valleys (below 1,500 feet). The northern Green Mountains are positioned to come away with the most snow with a 50-70% chance of seeing at least a half foot with a non-zero chance of seeing a foot through Thursday.
Below: Current probability of seeing at least 8 inches of snow by Thursday evening:
Wednesday morning will likely see very heavy, wet snow, with ratios lower than 10:1. The intensity of the snowfall could lead to some power outages, but the amount of snow that's expected in this phase isn't expected to be enough for a major power outage situation across New England. As the storm goes on and colder air filters into the storm, ratios will increase closer to 20:1. This means the snow will gradually become the lighter and fluffier kind as the storm goes on through Thursday.
For the higher terrain of southern New England, minimal accumulations are expected in the Berkshires, but they will likely see rain Tuesday night and a shorter duration storm than the mountains of northern New England. The Worcester Hills are interesting. They may see mixing or flakes Wednesday evening or night. Accumulations are not expected at this time, but later updates may allow for a dusting or quick inch of snow. The lower elevations of southern New England and the northern New England coast will see all rain.
RAINFALL
As the storm system intensifies early Wednesday morning, it will support a batch of widespread steady rain with embedded downpours. With marginal instability, some rumbles of thunder can't be ruled out. Southern New England and the northern New England coastal plain will see a widespread half inch to inch of rain. The rain will be heavy at times, but the bulk of the rain will come through within a few hours in the morning, which is helping to hold back amounts overall.
WIND
The main storm system will be strengthening as it slows down over Maine on Wednesday. This will allow for increasing wind gusts Wednesday afternoon into Thursday. All of New England will be under the gun for a very windy day on Thursday. This wind will come mainly thanks to a very tight pressure gradient. With the strengthening storm system stalling out to the northeast of Maine and a high pressure system over the Tennessee Valley, New England will be caught in the middle. The pressure difference between these two systems will be about 50mb (low pressure around 980mb and high pressure around 1,030mb).
Below: ICON showing potential weather Thursday morning, featuring a very tight pressure gradient over New England:
With good mixing and strong cold air advection in addition to this gradient, it will produce gusts of 40-50mph across nearly the entire region with sustained winds of 20-30mph. There continues to be some signals of isolated gusts in the 50-60mph range. Power Outages may be a concern with gusts at these levels. Areas that see light and fluffy snow through Thursday may see blowing and drifting snow, leading to reduced visibilities. Wind alerts will likely be issued over the next 12-24 hours.
Winds will very gradually die down for the rest of the week, but it will remain breezy through Saturday. The main damaging winds potential will be reserved for Thursday only. With cold air filtering into the region, it will also bring down feels-like temperatures.
COLD & FUTURE SNOW
New England will likely be entering a prolonged stretch of cold weather starting this weekend. The first half of January continues to look like it will be a cold for the eastern half of the United States. Currently, the core of the coldest air (relative to average) is poised to move south of New England, but the entire east coast will be susceptible to cold air/Arctic intrusions.
Below: 850mb temperatures showing the potential for a major cold air intrusion next week:
This will really kick in for the first full week of January. This will come as Arctic Oscillation and North Atlantic Oscillation dive deeply negative. This setup certainly supports some very cold air intrusions in the coming weeks. How intense these blasts will be for New England remain to be seen. As of now, it looks like the Midwest may get the coldest of it.
As for snow, a storm system will likely be driving across the country early next week, but trends have been toward this storm getting suppressed south of New England due to the cold air intrusion. It may come close enough for a glancing blow, but the chances for a major snowstorm are decreasing. Overall, the large-scale setup does support snow for New England, the question will be if a storm's track can take advantage of it.
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