Weak Systems to Move through New England Leading up to Thanksgiving

New England's weather over the next several days will be mainly influenced by a rather zonal flow. Zonal flow occurs when the jet stream lays generally flat across the country without pronounced ridges or troughs. This can often lead to low-impact and generally seasonable weather. This type of flow is quick, usually allowing for weaker, low-impact systems to push through the region. This stretch is no exception with a few passing systems leading up to Thanksgiving, but little in the way of any real impacts.

The first system will skirt to the south of New England through this afternoon. Light showers from this will continue to push out of southern and central areas from west to east through early this afternoon. No more than a quarter inch of rain is expected anywhere from this system. The system's cold front will be pulled across the region, allowing for a gradual clearing of the skies as drier air moves in. This may not occur for everyone before dusk as we push through the shortest days of the year.

On Sunday, a northern stream shortwave will dive through New England from Canada. This system will likely run through western New England before exiting near Cape Cod. This is a very weak system overall with a central pressure around 1,008-1,010mb range. For comparison, standard surface pressure (neither high nor low) is generally considered to be around 1,013mb, so this system is about as weak as it can be. Despite this, enough forcing and moisture should be present to produce scattered rain and snow showers.

For some, this system may only be able to produce a mostly cloudy afternoon rather than dropping actual precipitation. For others, periods of light rain and snow showers will develop from west to east through the afternoon and evening. Southern New England will be more apt to see rain showers (with mixing across the higher terrain).

Scattered snow showers are more likely for northern New England, mainly Vermont and northern New Hampshire. Light, fluffy snow with small flakes and snowfall rates in the 0.1 to 0.25 inch an hour range will create a "snow globe" effect across the mountains, leading to some very festive early season skiing across the Green and White Mountains.

Below: HRRR showing potential weather around late-afternoon Sunday:

The final system in this trio leading up to Thanksgiving will be another northern stream shortwave pushing from the Great Lakes region to the north of New England. This system was initially looking like it would interact with a southern stream system moving out of the south around the middle of next week. Now, it's looking more like the southern stream system will stay well south of New England, and we'll only see impacts from the northern stream. This has led to a reduction in the amount of precipitation expected as the northern stream on its own tends to have much less moisture to work with.

This system will likely spread precipitation across New England from west to east later Tuesday through Wednesday. Depending on thermal profiles when the system arrives after dark on Tuesday, northern areas may see the system begin as a wintry mix or snow. The system will be an inside runner, with its warm front moving across New England. This will lead to any mixing changing over to plain rain for northern areas. Southern areas will be rain through and through. A widespread quarter to half inch of rain is possible. The potential for heavier showers can't yet be ruled out, so trends will be watched.

The system's cold front will cross New England later Wednesday into Thursday morning. This timing should allow for a very mild day Wednesday with widespread 40s north and 50s south. It's certainly possible some areas of southern New England make a run at the low 60s. Cold air will begin to advect into New England after the frontal passage, setting up a cooler Thanksgiving. Drier air is expected to move in through Thanksgiving, with any lingering showers expected to end in the morning. A trough will likely settle over New England for the holiday weekend, leading to cold and potentially unsettled conditions.