Weekend Storm Likely Brings a Glancing Blow to New England

After a week of watching a potential coastal storm wobbling around southern New England, the flip-flopping between scenarios is settling down. Guidance is honing in on an "in-between" scenario, with a glancing blow rather than a direct hit or complete miss. A strong northern stream system will pass to the north of New England later Saturday into Sunday. This system will generally not phase with a southern stream system passing south of New England. This will keep this coastal storm on the weaker side as it passes outside the benchmark. The result will be minimal accumulations across southernmost New England.

Following the recent trend of New England storm systems over the past couple weeks, this one will be progressive in nature, quickly shooting through the area. Snow showers may break out after midnight across western areas and steadily fill in and spread eastward through the morning hours Sunday. The snow will likely be most widespread and reach its northern extent in the pre-dawn hours Sunday. This would be followed by snow showers shutting off from northwest to southeast through the remainder of the day, ending across Cape Cod last.

Below: Potential weather early Sunday morning (1st image) and early Sunday afternoon (2nd image):

Given the strength and energy of the northern stream system, colder and drier air will be pushed southward across New England, aiding to keep the southern system suppressed farther south. Without much phasing between the two systems, this will keep the southern system weaker as well. The two systems will help each other strengthen and turn into a more formidable storm well after passing New England. This will result in generally light to moderate snow for southernmost New England, with the potential for more unorganized snow showers farther north.

The going forecast will see steady snowfall mainly south of the Mass Pike. This will likely result in a general 1-3 inches of snow across Connecticut, Rhode Island, the South Shore and Cape Cod. Amounts will gradually taper off moving northward, with the rest of southern New England apt to see up to an inch. Depending on the exact track, these minimal accumulations may be able to extend into southern Vermont and New Hampshire as well.

Below: Current probability of at least 2 inches of snow:

There's been a good amount of uncertainty surrounding this system for the better part of this week now. This mainly stemmed from the fact that there are features of the forecast that could both pull the system north or suppress it south. Guidance has struggled to work out the level of interaction between the emerging system off the Mid-Atlantic and the stronger system to the north. With that said, bust potential is high with this one, and track changes will need to be watched closely right up until the event begins.

As we've said for the last couple days, it wouldn't take that much for the system to get pushed farther north, leading to more widespread snowfall and the northern extent of snow getting pushed farther north as well. It should be noted that this storm will be quick-moving and will remain weaker, even if this scenario were to play out. This would result in only a few more inches for southernmost New England (maybe 3-5 inches instead of 1-3 inches), not a major snowstorm.

The opposite would (naturally) occur if the storm ends up suppressed farther south due to a stronger push of cold and drier air from the north. These two scenarios are the less likely ones, with the going forecast above the snow probabilities graphic the most likely outcome. This just shows that this system is not set in stone and will need to be watched as it makes its final approach, as frustrating as that can be.

Below: The northernmost and southernmost mesoscale model runs for Sunday morning. NAM (the 1st one) represents the northernmost snow extent while FV3 (the 2nd one) represents the southernmost one:

This system will bring the first snowfall of the season to portions of New England. These areas represent the only places in New England not to have seen measurable snowfall yet, so all of New England will have seen snow by the end of this system (assuming it doesn't get shoved south, which is less likely than it getting pulled farther north).

After this storm passes, with whatever fanfare it brings, another blast of Arctic air is in store for Monday. This blast may be the closest one of the bunch seen over the past week. Wind chills will once again be dropping into the single digits for all, and sub-zero for northern areas. For those tired of this persistent cold, a major pattern change is in the works for the middle of next week.

Below: Euro showing potential temperatures Monday afternoon:

For those tired of this persistent cold, a pattern change is in the works for the middle of next week. The persistent and strong western ridge that has allowed for all this troughing and Arctic air to spill into New England will be breaking down. This will end the persistent ridge-in-the-west-trough-in-the-east pattern. The Pacific jet is expected to strengthen, leading to a more zonal flow. This will, in turn, allow milder Pacific air to spread eastward across the country.