A rather weak, short duration system will scoot across New England overnight tonight, with the center passing inside the benchmark, near Cape Cod. This will bring a quick shot of rain to southern New England and the northern New England coastal plain with snow across the interior. The main storm system will dart from around Kentucky Wednesday morning to around Nova Scotia by Thursday morning.
Precipitation is expected to break out Wednesday evening across western New England and steadily push east through the first part of Wednesday night. Initial precipitation may be rain or a mix for most in the evening before transitioning to snow from north to south and high elevations to lower elevations.
Below: NAM showing potential weather this evening:
By Wednesday night, a steady snow will likely be falling across much of interior northern New England with rain elsewhere. The rain/snow line will try to inch southward through the night. The storm will wrap up as quickly as it started, shutting down from west to east through Thursday morning. By midday, only scattered upslope snow showers will likely remain.
Below: NAM showing potential weather around midnight tonight (1st image) and around mid-morning Thursday (2nd image):
The quick-moving nature of the storm combined with the fact that it won't get all that strong will preclude a major snowfall (or rainfall) event for New England. Temperatures are marginal without much cold air in place, which also doesn't bode well for much snow. Through Wednesday night, the temperature will drop and precipitation rates will increase, allowing the rain/snow line to inch southward.
How close the rain/snow line gets to the northern New England coast is the greatest uncertainty. The farther south the storm tracks, the farther south the rain/snow line will get pulled. Either way, any snowfall along the coastal plain will be very minimal. The southern New England coastal plain will be all rain the entire time with some mixing in the higher elevations of southern New England.
As stated before, this will likely be a minor system, with minimal snowfall and rainfall amounts. Much of interior northern New England stands to pick up 2-5 inches of snow, with the most across higher elevations. Amounts will drop off heading lower in elevation and to the coast. The main question for the northern tier of New England will be if the northern stream system can pull its cold front south earlier, allowing a lighter, fluffier snow.
Whether mixing or snow makes it all the way to the coast will be rather inconsequential as amounts there will be very low either way. With marginal temperatures, this will be a heavier, wetter snow with ratios under 10:1 for most. Winter weather advisories may be posted for interior northern New England later today. The threshold for advisories is typically four inches within 12 hours for northern New England.
A colder air mass will follow this system, as they often do after storms in the winter. Cold air advection will begin on Thursday, but the cold air will really be felt starting on Friday, when afternoon highs will fail to make it to the freezing mark for a majority of New England. Southernmost New England may get to the upper 30s.
This colder air will set the stage for another system later Friday into Saturday morning. a clipper system will swing down from the Great Lakes into the Mid-Atlantic later on Friday. At the same time, a coastal storm well offshore will be moving northeastward. The clipper system will inject energy into the coastal storm and allow it to rapidly strengthen. With that said, this phasing of the systems still appears to happen far enough to the southeast of New England to only give our region a glancing blow.
Yesterday we mentioned that it was close enough that trends would still need to be watched. Over the last 24 hours, trends have subtly shifted westward a touch as the storm rapidly strengthens offshore. While lighter snow showers remain the consensus, this trend keeps the system close enough that future trends will need to be watched.
A track closer to New England could lead to higher moisture and precipitation for eastern Massachusetts and Downeast Maine. Again, this remains a low chance, but it can't be ruled out quite yet with the most recent trends. For now, the bulk of snow showers in New England will come from just the clipper system. This will result in a period of snow showers with minor accumulations Friday afternoon through Saturday morning. This will come as Nova Scotia and Atlantic Canada take the brunt of the storm.
Below: Probability of at least an inch of snow from Friday morning to Saturday morning:
Regardless of how the precipitation plays out this weekend, it will swing the door wide open for an arctic air mass to enter the region as very cold air pours into New England on the northerly flow behind the departing storm system.
This air mass looks to settle over New England on Sunday, when high temperatures will likely range from the single digits across the cold hollows of northern New England to low 20s in southern New England. Wind chills will likely be sub-zero for most of New England Sunday morning and lows will be around zero region-wide.
Below: Temperatures aloft Sunday morning showing the Arctic air mass wrapping around the backside of the storm system:
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