This week will once again feature multiple rounds of precipitation for New England. This will also come with a distinct cooling trend, where each day will likely end up a notch cooler than the last.
MONDAY
A line of moderate rain with embedded downpours continues to quickly race across New England. Many will be completely done with this line by midday. The exception will be much of Maine as the line will push through this afternoon. This line of rain is thanks to a cold front associated with a frontal system that will scoot to New England's north and west today.
With strong forcing and plenty of moisture to work with due to a strong southerly flow, a widespread half inch to inch of rain will fall (or already has fallen) across New England with this line. Winds will be gusty before and after the frontal passage, but an inversion will keep the strongest winds from reaching the surface. Gusts will remain below impactful levels.
Below: HRRR showing potential weather early this afternoon:
High temperatures today will be very mild as a strong southerly flow has led to a very mild start. Highs will generally come before the frontal passage, so in the morning or early afternoon for most. With that said, winds will continue from the southwest after the passage, so temperatures will be slow to fall this afternoon, leading to a mild day from beginning to end. Skies should begin to clear up this afternoon outside of Maine as drier air works in behind the front.
TUESDAY
Tuesday will feature a very brief ridge of high pressure. This will bring fair and calm conditions region-wide. Clouds will gradually increase through the afternoon and evening from southwest to northeast as our next storm approaches. Any precipitation associated with this system should hold off until well after dark. Temperatures will remain mild, but likely a notch lower than Monday.
WEDNESDAY
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.
Rain will likely arrive across southwest New England late Tuesday night before spreading northeast through the morning hours. As the surface low lifts into the Gulf of Maine, a dry slot may open up on the storm's south side, leading to a much drier afternoon for southern New England. On the north side of the system, strong forcing and lift will keep more widespread precipitation going for much of the day.
Below: NAM showing potential weather early Wednesday morning (1st image) and around midday Wednesday (2nd image):
The big question is how widespread wintry precipitation can get during the day on Wednesday. At this time, it doesn't look like cold air advection will be strong enough for truly widespread snowfall across New England. A mild, easterly flow off the ocean initially won't help snowfall, either. With that said, cold air damming in the mountains and foothills will likely allow for some mixing and snowfall.
The track of the storm near Cape Cod is generally a favorable one for widespread snowfall across Vermont, northern New Hampshire and northern Maine, the main problem is that there is no cold air whatsoever preceding the storm. The storm will likely start out as rain for almost everyone in New England. With that said, precipitation rates are expected to become strong enough to cool the atmosphere across interior northern New England to allow a switch to a mix and eventually heavy, wet snow.
Below: Likelihood of minor winter weather impacts from Wednesday morning through Thursday morning:
Despite being January, this storm's snowfall will likely be highly elevation dependent with mountain slopes and summits seeing much more snow than valleys, who may see little to no accumulations below 1,000 feet. Overall, a few inches of snow will be possible across far northern areas, with the most in the mountains.
The exact amount of snow (and how low in elevation it can get) will be highly dependent on the surface low's final track. A southern trend in the track will bring about more snow while a northern trend would push the rain farther north. With marginal temperatures, this will be a wet and heavy snow that clings to everything. The jackpot zones are currently poised to be the northern Green Mountains and northern Kennebec Valley/Maine Highlands areas. These areas currently have a 20-40% chance of seeing at least 6 inches of snow.
Below: Current probability of seeing at least 2 inches of snow through Thursday morning:
With a cold air dam posted to be set up across the Maine and New Hampshire mountains and foothills at the start of the event Wednesday morning, the initial round of rain may fall as freezing rain. Amounts will likely be very minimal, with a glaze of ice across interior New Hampshire and Maine. As the day goes on Wednesday, this freezing rain will likely either switch to plain rain or snow depending on elevation and how far north you are.
Below: Probability of at least a glaze of ice from Tuesday evening to Wednesday evening:
Southern New England and the northern New England coastal plain will likely see all rain once again. The only exception will be the Berkshires, which could see a transition to snow during the most intense bands of precipitation, similar to the Greens just to the north. Another half inch to an inch of rain is likely for areas that are all rain from start to end.
THURSDAY
As Wednesday's storm deepens in the Gulf of Maine, it will slow down. By Thursday morning, the storm will likely be sitting just north of Maine. This will allow for a deeper northwest flow and stronger cold air advection. This will continue the cooling trend that will last through the weekend, with each day topping out a notch lower than the last.
With the storm sitting to the north of Maine, it will allow for continuous broad cyclonic flow over New England. This will bring persistent upslope snow showers to the mountains as well as eastern Maine, resulting in additional (albeit minor) snow accumulations through Thursday. Outside of the mountains and eastern Maine, the day will be dry, but the cyclonic flow will likely allow for puffy clouds to develop in the afternoon along with gusty winds.
FRIDAY & WEEKEND
The theme for late this week will be the continued cooling trend. By Friday, temperatures will be back to the 20s north to 30s south, which will continue through the weekend. The low pressure system will continue to slowly meander north of Maine as a blocking high over Greenland keeps it from making a timely exit. New England will likely be entering a prolonged stretch of cold weather starting this weekend. While colder, this period is also looking dry.
BEYOND
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. 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.
Below: AO and NAO Index from the last three months. The current forecast is toward the end of the line, where the dotted line begins. Both of these in deeply negative territory in January is a decent signal for cold:
The question naturally gravitates toward if any storms will be able to take advantage of the colder weather and bring snow. Conditions look mainly dry for late next week and into the start of the weekend. Heading toward the end of next weekend into the start of next week may get interesting. The large-scale setup will favor a storm system sliding across the country. What this storm does when it reaches the coast will need to be watched. Recent trends have begun to suppress the system to the south.
If this incoming push of cold air is too strong, it will suppress storm tracks to New England's south. For New England to get a snowstorm during this time, it would need to be a balance of cold air, timing and jet stream position.
Comments