A coastal storm will approach New England this weekend. At the same time, a robust northern stream disturbance will move into New England. The two systems will likely interact, leading to a period of heavy snow in interior northern New England and a soaking rain across southern New England. The way things are trending, there will likely be a situation on Saturday with a rain/snow line starting south and lifting north during the day.
Right now, models are beginning to come together on a track for the coastal low between Cape Cod and the benchmark Saturday night. The interaction with the northern stream will allow precipitation to break out well ahead of this, likely Friday night or earlier Saturday morning. Current trends have the rain/snow line beginning near the border with southern and northern New England, though it wouldn't be surprising to see the higher elevations of southern New England start with a snow or mix.
The northern stream will bring mainly snow showers across the region before the moisture plume from the southern stream arrives, bringing with it more mild air and allowing the change to a mix or rain to begin. The storm is looking to shut down from west to east throughout Sunday morning.
Euro showing potential weather Saturday morning and Saturday evening. Remember this is just one model, but other major models generally agree with a rain/snow line pushing north during the day:
This is looking to be yet another moisture-rich storm, which will help produce both heavier snowfall and heavier rainfall. The million dollar question will be how far north the rain/snow line can push north and how quickly it is able to do so. Being a spring snowstorm, there's no doubt that elevation will play a role in snow totals.
Areas that remain all snow will have the chance to see upwards of 8 inches of snow with amounts up to a foot across the northern Green and White Mountains. Right now, it looks like the jackpot zone will be across northern New Hampshire and the Maine mountains. An area with the biggest uncertainty is currently near the Maine coast (up to 30-40 miles inland) as we'll need to watch just how far the rain/snow line can push.
There does remain some uncertainty in just how much snow will fall. Part of this has to do with the level of interaction with the northern and southern streams. More phasing will allow more moisture farther north, but less phasing will allow a more eastward track and keep the heaviest moisture south, where rain is expected. Despite these uncertainties, there is a growing chance for portions of northern New England to see at least 6 inches of snow.
Probability of seeing at least 6 inches of snow from Saturday morning to Sunday morning:
Another part of snow accumulations will be the snow consistency. A drier snow will be more likely farther inland while the snow becomes wetter as you head closer to the coast. Drier snow will pile up faster than wetter snow. The snow consistency will have an impact on power outages. Areas that will see the most snow will likely see a drier snow, which will help with keeping outage numbers down.
In southern and central New England, this will primarily be a soaking rain event. While heavy snow falls in the mountains, heavy rain will fall farther south. Saturday will likely be a washout. The heaviest of the rain will likely come more toward Saturday afternoon and into the evening when the coastal low makes its closest pass. Interaction with the northern stream will help draw the coastal low farther west, which will place the moisture plume over southern New England.
Euro showing potential weather Saturday evening. There's still a spread in models on exactly how far north the rain/snow line will be, but they agree on a period of steady to heavy rain in southern New England:
A widespread 1-3 inches of rain will be possible. This may lead to minor urban/poor drainage flooding. The typical problem rivers (Pawtuxet and Wood Rivers in Rhode Island, mainly) may reach minor flood stage. At this point, widespread, serious flooding is not expected.
There is little to no threat regarding coastal flooding and high winds with this one. It will be a precipitation-based event. As the storm pulls away, cold air may get wrapped around the system, causing some areas (mainly in central New England) to switch back to a mix or snow as the system pulls away.
Sunday has been trending drier across New England as it does appear that the storm will pull far enough away to keep precipitation out of New England for the day. It will likely remain mainly cloudy and breezy for eastern areas. This late-March chill will likely stick around through at least the middle of next week.