But I don’t think a large, significant storm will affect our region, and Boston won’t see any snow. In the region there should only be light or constant rain. Right now, I think this modest storm has a good chance of causing a 2-inch layer in some higher elevation locations in western Massachusetts and northern New England. It just won’t be cold enough in New England for widespread snow: the Boston metro area may end up with about an inch of rain, much less than we saw last week. We may see some flakes mixing at low elevations at times, but the chances of anything sticking, like on I-95 and I-495, are very low. A coastal storm and a possible nor’easter are possible Thursday afternoon through at least Friday, producing some snow at times across the interior. Boston Globe The forecast outlook is nowhere near the storm’s track and strength, and my thoughts may change as the week progresses. But I just don’t think it’s a major storm. But there is a lot of buzz online right now and I want to discuss some details and what the models are showing right now. The jet stream paints the picture: Storms often develop on the eastern side of a U-shaped trough or trough in the jet stream. This is because the winds aloft in that area are faster and separate, creating what we call upper-level divergence. As air expands high in the atmosphere, air near the surface rises rapidly to fill the void, creating an area of low pressure. Those fast winds also allow the trough to intensify as it follows the jet stream “highway.” A deep southward arc in the jet stream should cause a coastal depression by Thursday and move near New England sometime on Friday. Boston Globe What the GFS model shows The GFS model (the Global Forecast System or US model) takes the storm on a more inland track, which would favor rain in much of New England. However, colder air could allow snow to form at higher elevations, particularly in the mountains, Thursday afternoon into Saturday afternoon. Closer to the coast, including Boston, a few snowflakes could be seen mixing with periods of light rain. The GFS suggests an inland track, with rain for most and snow at higher elevations Thursday afternoon through Saturday afternoon. Pivotal WeatherWhat the European model shows The European model (ECMWF or European Center for Medium-Range Weather Forecasts) takes the storm further from the coast, giving it more of a classic northeasterly track, but still a little further east to avoid major impacts. That would provide a better chance for snow in parts of interior New England, but even this scenario favors more rain than snow overall. Again, accumulated snow would likely disperse and concentrate at higher elevations. The Euro model shows a more offshore track, which fits the northeast profile, but still with more rain than snow. The snow is more scattered and at higher elevations. Pivotal Weather’s forecast snow totals are all over the map. The trend here is for snow totals to stay inland. Between the combination of NWS models, the European and Euro-AI models, and the GFS, there is a wide range of what snow totals can look like. Patchy layers up to 2 inches are more than likely, but GFS and Euro-AI models show a couple of 2- to 4-inch pockets at higher elevations in northern and western New England. Here are four total snowfall forecasts from the combination of NWS, GFS, European and Euro AI models showing a wide range of later snowfall. this week.Pivotal WeatherSo which model is more reliable? Dave Epstein, the Globe’s contributing meteorologist, said he typically leans toward the euro, noting that “it’s not always 100 percent right, but in general, you want to stick with what’s going to be mostly right.” This storm is obviously worth watching and requires continued forecasting. But for now, I’d call this a modest fall storm and not a Northeastern blockbuster. Boston continues to see light rain, with maybe a flake or two of snow, but anything that accumulates would be a long way from the city, in the higher elevations of western Massachusetts and northern New England. Ken Mahan can be reached at ken.mahan@globe.com. Follow him on Instagram @kenmahantheweatherman.
