Latest Trends on Incoming Storms for New England

New England's next system will arrive later Sunday and into Monday. This system will take an interior storm track. This would result in another setup with a warm front lifting northward, resulting in a milder storm. This milder air will be overrunning colder air settled at the surface, so mixed precipitation or snowfall is possible across interior northern areas and the higher terrain, with a switch to plain rain occurring from south to north. This system appears that it will be quick-moving as well, resulting in a low-impact system.

Northern New England may see some snow showers break out Sunday morning as the warm front lifts northward. Rain and snow will generally fill from west to east as the day goes on. Coverage will likely peak in the evening. By the time precipitation arrives for southern and central New England, temperatures will have already warmed well beyond freezing, allowing for all plain rain. Snow across northern New England will gradually flip to plain from from south to north as the afternoon and evening wear on.

Below: HRRR showing potential weather around mid-morning Sunday (1st image) and Sunday evening (2nd image):

For the mountains and northward, the system may move fast enough for this to be all or mostly snow. That is to say the bulk of precipitation may be moving out by the time the rain/snow line would arrive. This system is weak overall, and the quick-moving nature of it will limit accumulations. A couple inches of snow is possible, mainly across the northern half of Maine and northernmost New Hampshire.

Once this system passes, it will drag its cold front across the region early Monday morning. A secondary front will cross New England through Monday morning as well. This will help set the stage for colder air to set up across New England before the arrival of our next storm system later Tuesday and Tuesday night. This storm will be stronger than Sunday night's and will be able to produce more snow.

A deepening low pressure will likely be pulling out of the Mid-Atlantic and pushing northeast toward New England. The overall setup and position of this system will favor cyclogenesis, especially with the colder air setting up over land and a still relatively warm ocean here at the beginning of the season. Guidance is becoming to hone in on a track near, or just inside the benchmark.

General timing of this storm right now looks like it will enter into New England during the day Tuesday. The storm will steadily spread from southwest to northeast through the day, with most possibly not getting into the action until Tuesday afternoon. The peak of the storm is still lined up to occur for most Tuesday evening through the night. A rapid clearing out of the system through Wednesday morning remains the favored outcome.

As stated before, guidance seems to be honing in on a track near the benchmark. This is represented by loose clustering of ensembles near this point for Tuesday evening. This track would result in steady snowfall being the dominant precipitation type for a vast majority of northern New England as well as interior southern New England. This would place the storm's jackpot zone across central New England (southern ME, NH, VT; northern and western MA). How much could potentially fall in this jackpot zone remains to be determined.

Below: Probability of impactful winter weather Tuesday through Wednesday morning:

Despite the seemingly narrowing possibilities of the storm track, this does remain an issue that should be worked out within the next 12 to 24 hours. This is because the parent trough of this system remains in the Gulf of Alaska as of Saturday morning. Guidance can struggle to get a grasp on a system until it moves over land.

Once this system enters the western United States, things will start to become more clear and confidence will begin to build in these current trends. Should the storm trend farther north or west (closer to New England) the rain/snow line would get pushed northward and farther inland. If it were to wobble south or east (which is currently less likely than wobbling west), the opposite would happen with the rain/snow line. The area of most snow would also wobble north or south depending on the overall track.

Below: Two model runs for Tuesday evening. The first one, which is ICON, represents the westernmost track (right over Cape Cod) while the second one, CMC, represents the easternmost track. This is as of Saturday morning:

Another issue for the rain/snow line outside of the track will be the overall timing of the storm. Early and late season storms have a much easier time depositing snow when they come through overnight rather than during the day. As of now, a bulk of the system is expected to move through overnight, which would help snowfall. With that said, should the storm spark up around midday or in the early afternoon Tuesday, there may be several hours of minimal accumulations. This system will likely be quick-moving as well, so those "lost" hours could prove major when it comes down to it, should the storm play out like that.

Overall, there remains a large spread in potential snowfall. The National Blend currently has a 6-7 inch difference between the 25th and 75th percentiles. This kind of spread between these percentiles indicates a high level of uncertainty. There's currently a high chance for at least an inch of snow across interior southern New England (up to 90%), but only moderate to low chances of more than 6 inches (30-50%). Closer to the southern New England coast, probabilities are much lower (less than 50% for 1 inch). These numbers will change over the next 24 hours.

Below: Probability of minor and moderate winter weather impacts:

There will be no downstream blocking ahead of this system, so a quick exit is likely Wednesday morning. This will help to keep snowfall amounts in check as well, as this may be a 12 hour storm with rapid clearing at the end. This may end up being a classic 4-8 inch jackpot zone snowfall. Exactly where that sets up is the question. It will remain cold next week after this storm.