Frontal Boundary Set to Create a Messy Weekend for New England

New England will remain in a trough on Wednesday. Another disturbance will rotate through this trough, spawning an area of low pressure to the south of New England. This system will remain offshore of New England, keeping widespread, steadier precipitation offshore. Even without the help of the organized, offshore low, the trough will keep New England under broad cyclonic flow. This will allow for another round of scattered, pop up snow and rain showers throughout New England in the afternoon.

Below HRRR showing potential this afternoon:

Heading into this weekend, the weather setup will be a mess, very typical of springtime in New England. An extended period of unsettled weather with multiple waves of precipitation looks likely. This will come as a frontal boundary stalls over or just to the south of New England. An area of high pressure over Canada and another one offshore to the south of New England will help complicate the precipitation types. Waves of energy will ride along the waffling front.

With an area of high pressure set up to the north of New England, it could keep cold temperatures locked at the surface while the air aloft warms. This means every precipitation type (rain, snow, sleet, freezing rain and graupel) will be possible across New England from Saturday through Monday (we have a general breakdown of the days below).

As the wavy boundary wiggles around and daytime heating occurs on all three days, precipitation types will be changeable across New England with some areas likely seeing all precipitation types at some point (like we said, it’s quite a mess). With all this uncertainty, it's impossible to try to realistically give estimates on amounts of snow, rain and ice. The farther north you go in New England, the better the chance for more prolonged wintry weather. Southern New England looks to be mainly rain at this point.

Below: CMC showing a basic evolution of the system from Friday evening through Monday night:

A significant temperature gradient continues to look likely across New England with mild temperatures bringing rain to the south of the front and much colder temperatures with snow and mixing to the north of it. The steadier and more widespread precipitation will likely fall on the north side of the front with much more scattered showery activity to the south of it.

The temperature contrast looks like it will be most stark on Saturday. By the afternoon of Saturday, southwest New England (Connecticut, western Massachusetts and maybe Rhode Island) will push into the warm sector, allowing temperatures into the 60s. Should clouds scour out as the precipitation lifts north, low to mid 70s will be possible. To the north of the front (which will likely be most of New England) it will be chilly and raw, in the 30s and 40s. A temperature difference of 40+° is possible across New England.

Below: CMC showing temperature departure from average Saturday afternoon. Note how sharp the cutoff in mild air is across southern New England:

This kind of setup is rather typical of the transition period from winter to spring in New England. As the jet stream slows down and generally lifts north, weather systems have a tendency to get hung up. Frontal boundaries stall and bring days of unsettled weather and raw conditions. This is the first of at least a few stalled frontal boundaries over the next couple months. Given it's still March and the setup is very favorable, this one has the headache of mixed precipitation rather than just rounds of rain showers.

While it remains difficult to break down this system in detail, the general idea of how each day will play out is starting to come together. Here's a breakdown of what we'll be watching for each day. This remains subject to changes, it's just a general look at current trends:

FRIDAY NIGHT-SATURDAY

The first wave of precipitation with this system will likely arrive in the early morning hours Saturday. This will mainly be a cold rain for southern New England (with some mixing at higher elevations). In northern New England, a period of snow showers is likely in the morning before daytime heating allows a switch to mixing and rain from south to north. Snowfall accumulations for the north appear that they will be on the lighter side.

Below: Probability of impactful winter weather Saturday to Sunday morning:

In southernmost New England, showers will likely lift northward in the morning with much more scattered or isolated activity in the afternoon. Clouds may begin to clear in areas south of the front. This is when temperatures could shoot into the mid 60s to mid 70s for southwest areas. Much of New England will likely remain on the chilly, raw and damp side, however. Trends in exactly where the front sets up will be watched as trends farther south in the coming days could lead to a big temperature bust for Connecticut.

SUNDAY

A renewed wave of energy looks to push in on Sunday. It currently looks like the boundary will waffle back southward, with all of New England cooling off. Sunday will have the chance for a real mess of precipitation across New England. With the boundary dropping back south, cold air will likely remain locked at the surface. Meanwhile, an offshore high pressure system well south of New England could bring about a southerly flow aloft.

Below: Probability of impactful winter weather Sunday-Monday morning:

This may set up a warm nose with the potential for a wide area of a wintry mix across northern New England. Southern New England looks to remain mostly plain rain showers and northernmost areas may remain all snow. The area in between will need to be watched for potential ice.

Below: GFS showing general precipitation trends for Sunday afternoon:

SUNDAY NIGHT-MONDAY

Warm air advection will likely continue to increase from south to north, gradually switching wintry precipitation to plain rain from south to north. This will likely occur through the day Monday as daytime heating occurs. This will come as the main low pressure system working eastward across the country lifts through New England, pulling the stalled boundary northward as it does so.

Below: Current weather map for Monday (March 31):

This system looks to clear out by Tuesday morning with high pressure building into the region. The jet stream looks to set up near or over New England through the extended period. This will keep the storm track over New England with another system potentially moving in later next week.