A weaker, fast-moving storm will slide west to east near, or just to the south of, southern New England later today and into tonight. As it does so, it will lift a warm front toward the region. A cold front will also be dropping through New England today on the heels of a separate system passing to the north this morning. These two fronts will set up a rain event for much of southern New England, snow across northern New England and a corridor of a rain/snow mix in central New England.
The overall timing of the system has slowed down a bit, with a bulk of the precipitation arriving a bit later and ending a bit later Saturday morning. Light and scattered showers will likely break out throughout the morning hours across southern New England. Precipitation will fill in and gradually rise northward through the afternoon hours.
Below: HRRR showing potential weather around midday today (1st image) and around mid-afternoon today (2nd image):
The rain/snow line will likely initially be near the New Hampshire Lakes Region before collapsing southward in the evening. Through the evening is likely when precipitation will be at its steadiest and most widespread. Rain and snow will continue to steadily push eastward into Maine during this time. Rain and snow will gradually wind down and break up through the overnight hours into early Saturday morning.
Below: HRRR showing potential weather this evening (1st image) and very early Saturday morning (2nd image):
The later timing of the onset of precipitation further decreases the chances of mixed precipitation this afternoon and evening. Temperatures aloft and at the surface will have risen above freezing in southern New England by the time widespread precipitation arrives. Strong warm air advection will be occurring through the morning, kicking yesterday's brief arctic blast out of the area.
For northern New England, thermal profiles are supportive of either snow (for most) or rain (for southernmost New Hampshire and southwest Maine) at the onset. This is looking increasingly likely that it will be mainly snow to rain with possibly a brief period of freezing rain during the transition. This all comes as warm air initially pushes north amid warm air advection before the cold front pushes southward, dropping temperatures once again.
Below: HRRR showing hourly temperatures from mid-morning today through about midnight:
In its simplest form, the northern tier of New England will see cold air from beginning to end, resulting in all snow. Areas generally south of the Mass Pike will see warmer air arrive before precipitation, resulting in all rain. Between the northern tier and the Mass Pike (northern MA, southern NH, VT, southwest ME) is where the battleground between the warmer and colder air will occur. The colder air will gradually win out from north to south, but it will be too little, too late for much accumulation for many.
The storm will not be very amplified, so the primary motion will be west to east rather than south to north. This will create a sharp northern cutoff in snowfall for the northern tier of the region, with little, if anything, falling across northernmost Vermont, New Hampshire and especially northern and possibly even central Maine.
Below: FV3 showing potential weather late tonight. This model is currently the northern outlier among major mesoscale models:
As far as 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 minor event. Many in central New England (northern Massachusetts, southern Vermont, New Hampshire & Maine's coastal plain) will likely end up with 1-3 inches, with amounts gradually dropping farther south in this area.
Much of southern New England will see little by way of snowfall and the northern tier will see a sharp cutoff in widespread snowfall, significantly reducing any totals there. Snow ratios will also be on the lower end, likely 6-10:1, indicating a wetter snow, though the snow will lighten up as the colder air pushes in through Saturday morning.
The cold front pushing southward will clear New England by Saturday morning, after this storm has pushed away. Drier air will be rushing back into the region amid a renewed northwesterly flow. The day will likely be similar to this past Wednesday, with high temperatures likely reached in the morning with falling temperatures in the afternoon amid the cold air advection behind the front.
Strong high pressure will build into the region for a majority of the weekend, bringing dry and calm conditions. Strong radiational cooling is expected for Saturday night amid the high pressure with mainly clear skies, light winds and a refreshed cold air mass. Overnight lows will likely range from the single digits south to negative teens north.
On Sunday night, an Alberta Clipper will zip through the region, bringing a period of light snow for most with a mix across southernmost New England. A warm front will lift into New England Monday morning, changing any leftover precipitation from snow to rain in the morning from south to north. Wrap-around snow showers are expected later Monday for the northern tier.
This will likely be yet another quick hit of snow with low-impact and sub-advisory totals. A widespread 1-3 inches is possible, especially for northern New England. Southern New England will likely see lesser amounts, though this will depend on the final track and trends will be monitored. As of now, probabilities of greater than four inches of snow are capped at 10%.
Below: Probability of at least an inch of snow Sunday into Monday morning:
Another storm system in this active stretch looks to arrive around the middle of next week. Early indications are for an inside-runner type of setup, with more widespread mixing potential. This could be a situation where snow changes to rain from south to north as it goes on, though this is just an early trend and shouldn't be taken to heart yet. This system will come into better view with time, so we'll leave it at that for now.
Below: Model roundup (Euro, GFS, CMC & AIFS) for Wednesday evening/Thursday morning:
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