New England's active pattern will continue, with the next system on the way for Friday and Friday night. A northern stream system with limited moisture will pass to New England's north Thursday night into Friday. This will lift a warm front across New England, bringing a quick end to Thursday's Arctic blast. While it won't actually get truly warm, or even mild, it will be noticeably warmer than Thursday.
Some light snow showers are likely to accompany the warm front and passing low pressure system Friday morning across the northern third of New England. These will move west to east throughout the morning hours, amounting to little, if any, accumulations. Farther south, weaker forcing will amount to very little to no precipitation in the morning. This initial warm front will help set the stage for an approaching southern stream system that will pass New England later Friday into Friday night.
This system will be a fast-moving, de-amplifying system that will track mainly west to east across the Ohio Valley and near, or across, southern New England. This will gradually spread precipitation into New England from south to north beginning mid to late morning for southernmost New England. The northern extent of precipitation, as well as precipitation type, will be determined by the track and timing of the low pressure system.
The timing of the southern stream system will likely see spotty and light precipitation break out across southernmost New England in the mid to late morning hours. The system will initially be battling dry air, so it will take some time for precipitation to become more widespread and steady. This will occur through the afternoon hours as precipitation fills in and pushes northward.
Below: HRRR showing potential weather around mid-morning Friday (1st image) and mid-afternoon Friday:
By the evening, precipitation will become the most widespread and steadiest as the system makes its pass around southern New England. At this point, precipitation will make its furthest push to the north. Overnight trends have led to a sharper northern cutoff of precipitation, so far northern Vermont and New Hampshire may see little from this system. This southern trend is most noticeable in Maine, where it's possible only the coastal plain/southern half of the state sees much precipitation. The northern cutoff remains a large question.
Below: HRRR showing potential weather Friday evening:
The overall timing of the onset of precipitation will be important, especially for southern New England. Temperatures this evening will drop into the teens and low 20s in southern areas and the single digits across the northern tier. Once the warm front begins to move in, temperatures will begin to rise after midnight from south to north. Should precipitation begin falling before surface temperatures rise above freezing, then a period of freezing rain will be possible before a switch to plain rain. A winter weather advisory is in effect for western counties of southern New England for this risk.
At this point, it appears that the steadiest precipitation will hold off long enough to allow sufficient warming to avoid widespread freezing rain across southern New England. A decently strong southerly low-level jet will also be in place, warming temperatures aloft, allowing for mainly plain rain across areas south of the Mass Pike.
Below: HRRR showing hourly temperatures from this evening through mid-morning Friday. Note the thin red line represents the freezing mark:
From southern Vermont to central New Hampshire and into much of Maine, thermal profiles will be supportive of this being a mainly snow event. For central New England (northern Massachusetts, southern New Hampshire and southwest Maine), precipitation types are the most uncertain. With milder air moving northward and colder air diving southward, this area will be the battleground between rain and snow (and freezing rain and sleet).
With multiple features in play, thermal profiles will be sensitive, especially in central areas, where mild air aloft will be battling with colder air diving south. At the surface, temperatures will likely be marginal, leading to the potential for a decent mix of both rain and snow (as well as the potential for freezing rain and sleet) in the pink area on the map above.
Exactly how the rain/snow/mix line plays out will be heavily determined by the storm's final track, which has been a major point of contention among guidance for the past few days. The farther north the system can lift, the farther north the rain/snow line will be pushed and vice versa.
The storm will not be very amplified, so the primary motion will be west to east rather than north to south. This will create a sharp northern cutoff in snowfall. Interior Maine has the greatest uncertainty in just how much of the storm will be able to affect the state. Overnight trends have been for a sharper northern cutoff, leading to less impacts across interior Maine.
Below: FV3 and HRRR showing potential weather late Friday night. FV3 currently represents the northernmost solution while HRRR represents the southernmost solution. You can see two very different scenarios playing out for Maine:
No matter what the final track of the storm ends up being, colder air will be crashing southward from northern New England Friday evening and night. This will support a changeover from rain to snow from north to south as the night goes on. With the quick motion of the storm, the main question will be how far south the colder air can get in New England before the storm wraps up early Saturday morning. As of now, the best chance for accumulating snow in the pink area on the above graphic will be across southern New Hampshire.
Below: NAM showing hourly temperatures from Friday late afternoon to early Saturday morning:
As far as the ever important question of how much...this will be a quick-moving system that will not be rapidly strengthening as it passes New England. Both of these will lead to a more minor event, akin to what New England has seen through much of this winter so far. Areas that see snow from beginning to end will likely stand to see 3-5 inches of snow.
The greatest snowfall amounts will set up just to the north of the rain/snow line. Amounts will likely drop steadily moving farther north in New England. Amounts will drop off heading southward due to mixing and rainfall cutting into totals. With uncertainties in the final track, substantial changes to snowfall forecasts remain possible, especially across interior Maine. With that said, we're not putting out a snowfall forecast map yet (hopefully that'll come this evening). Below are current probabilities of at least 2 inches of snow.
Below: Current probabilities of at least 2 inches of snow. It wouldn't be surprising to see the blue areas generally shifted south in updates later today:
Accumulations of plain rain, freezing rain and sleet across central and southern New England will not be substantial and will generally be unimpactful. Overall, it will be a cold, raw and wet day (and into the night) for southern New England. With that said, should a glaze of ice from Friday morning, surfaces will be slick.
Below: Current probability of at least a glaze of ice Friday:
The storm will wrap up quickly Saturday morning. The colder air crashing into New England will set up a cold weekend with a very cold night Saturday night to Sunday morning. This will come with a strong area of Canadian high pressure, so it will be a quiet weekend. The active pattern will continue with another Alberta Clipper later Sunday into Monday. This will bring another quick round of snow (north) and rain (south) to New England.
Below: Current weather map for Monday morning (February 3):
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