Messy Storm to Bring Snow, Ice and Rain to New England: Impacts, Timing
- Tim Dennis
- Mar 28
- 5 min read
A frontal boundary will stall over New England Friday night. This boundary will be sandwiched between an area of high pressure over Quebec and another one over the Atlantic to the south. With an area of high pressure set up to the north of New England, it will keep cold temperatures locked at the surface across northern New England while the air aloft warms as a southerly flow develops around the offshore high. This means every precipitation type will be possible across New England from Saturday through Monday.
ALERTS (as of Friday morning)
TIMING
The first wave of energy will travel along this frontal boundary Friday night with the leading edge arriving in western New England late tonight. Precipitation will generally spread west to east through the morning hours. This will be rain across southern and central New England with snow across the northern tier. An area of mixing will occur in between. Snowfall rates across the north will likely pick up quickly early Saturday morning.
Below: HRRR showing potential weather around midnight tonight (1st image) and in the pre-dawn hours Saturday (2nd image):
During the daytime hours Saturday, shower activity will become much more isolated in nature south of the frontal boundary while widespread precipitation continues across northern New England. The rain/snow line will inch its way northward through the day as warmer air aloft gradually works into the system and moves northward.
Below: HRRR showing potential weather around mid-morning Saturday (1st image) and mid-afternoon Saturday (2nd image):
The stalled boundary will likely get pushed southward Saturday evening and overnight as the initial wave of low pressure passes. This will allow scattered shower activity to drop back southward for Saturday night. By Sunday, the main area of low pressure over the Great Lakes will begin to push eastward, this will gradually lift the front back northward as a warm front, resulting in more periods of showers for southern New England.
Across northern New England, cold air damming will remain in place, keeping surface temperatures cold. This may result in a wide area of sleet and freezing rain during the day. Like Saturday, precipitation will be more widespread across northern areas with much more minimal activity farther south.
Below: Potential weather Saturday night (1st image) and early Sunday afternoon (2nd image):
SNOWFALL
The heaviest and most widespread precipitation will likely fall on the northern periphery of the low pressure system riding along the front for Saturday. Overall, the heaviest of the snow may fall within a rather narrow band. As of now, this band looks to extend from northern Vermont through the White Mountains and across western Maine. These areas will have the best chance at seeing 3-6 inches of snow, with some higher amounts likely.
There will be the potential for moderate to heavy snowfall rates where the system remains all snow across the northern third of the region. This will come as high levels of moisture will stream northward around the southern high pressure system. There is currently moderate probabilities of seeing at least one inch an hour snowfall rates Saturday morning across northern Vermont, New Hampshire and western Maine.
There will likely be a sharp cutoff in snow totals moving southward toward southern Maine, the New Hampshire Lakes Region (and points south) and central Vermont. Exactly where this cutoff occurs needs to be monitored. There could also be a decently sharp cutoff in snowfall across eastern Maine as well, with places like the Bangor area potentially only seeing minimal accumulations while Caribou sees partly cloudy skies.
Below: Probability of at least 2 inches of snow:
The heaviest of the snowfall is likely Saturday morning with limited accumulations expected in the afternoon. As the warm nose of air rises northward aloft, snowfall will be replaced by sleet and freezing rain heading into Saturday evening and Sunday. A vast majority of snowfall from Saturday through Monday will fall at the onset of precipitation Saturday.
ICE/MIXING
With high moisture streaming around the high pressure to the south, this may also allow for bouts of steady precipitation within the mixing corridor as well (not just snowfall). Areas that see primarily freezing rain for periods from Saturday morning through Sunday night (this zone will be moving around throughout the weekend) could see upwards of 0.20-0.50 inches of total accretion by Sunday night.
Current trends have this area most likely to set up over central Vermont into southern New Hampshire away from the coastal plain. These areas may see an elevated power outage threat on Sunday due to the ice on top of some snowfall. It takes about a quarter inch of ice to begin to create isolated problems. Getting into the half inch area will begin to create more widespread issues.
There remain strong indications of cold air damming across all of northern New England and potentially along the higher elevations of southern New England. This will help keep colder air locked at the surface and will likely allow for a wider area of a wintry mix of freezing rain and sleet mixing with plain rain. The boundary will not be completely stagnant throughout Saturday and Sunday. It will be wavering back and forth. This will allow the rain/snow/mix zones to waver north and south as well.
Below: Diagram of cold air damming:
A pronounced warm nose of air aloft will begin to enter New England Sunday and push northward later in the day through Sunday night. Throughout Sunday, freezing rain will likely gradually become more widespread as the layer of warm air aloft deepens over the cold air trapped at the surface across northern New England. Southern New England (along with southeast New Hampshire and Maine's immediate coast) will likely be warm enough at the surface for plain rain showers for the most part. There will be the chance for minor accretion across the northern Worcester Hills and Merrimack Valley.
TEMPERATURE CONTRAST
The frontal boundary will likely be draped across Massachusetts on Saturday. There will likely be a 40+° temperature difference across New England for highs Saturday. While that is indeed a decent temperature gradient across the 200 miles from say Hartford, Connecticut to Berlin, New Hampshire, the gradient will be much sharper than that. There could be a 30-40° difference just from Hartford to Fitchburg.
Below: Temperature departure from average Saturday afternoon:
There are still the possibilities for trends to the south or north. With the expected temperature contrast, any shifts could lead to big temperature busts for Saturday afternoon. Given the expected air mass with a shallow layer of cold air at the surface and the potential for cold air damming, it's more likely that the front would trend farther south rather than farther north. With that said, mid 60s to low 70s remains the going forecast for southwest New England while much of the rest of the region remains in the 30s and 40s.
Below: HRRR showing potential high temperatures Saturday afternoon:
MONDAY
Warm air advection will likely continue to increase from south to north, gradually switching wintry precipitation to plain rain from south to north Sunday night and Monday. 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.
Just about all of New England is expected to get into the warm sector by Monday. This will bring much warmer temperatures and plain rainfall Monday into Monday night. Moisture will once again increase ahead of the low pressure system's arrival, allowing for steady rain and gusty southerly winds.
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.
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