Ice, Snow, Rain Continues Through the Weekend for New England
- Tim Dennis
- Mar 29
- 4 min read
Multiple waves of low pressure will ride along a frontal boundary draped over New England. This boundary extends back toward Wisconsin; all of that energy to the west of New England must slide through the region over the next few days. As these waves move through New England, the boundary will waffle north and south, causing the rain/mix line to waffle north and south with it. This will lead to a prolonged period of wintry weather, mainly mixed precipitation, after a round of snow for the northern tier this morning (a general 3-7 inches has been reported so far as of writing).
After the main round of precipitation moves through this morning, there will likely be a lull for much of the region this afternoon. It won't be completely dry everywhere, but precipitation will likely become lighter, scattered and more showery in nature. Precipitation is expected to fill back in for southern and central New England this evening through the overnight hours. This will gradually lift northward through the day Sunday.
Below: HRRR showing expected hourly weather from early this afternoon through Sunday:
The greatest impact from this system will likely be the potential for moderate to considerable icing over portions of New England. Winter storm warnings have been issued mainly for freezing rain across southwest New Hampshire with higher snowfall likely in northern Vermont. Winter weather advisories have been issued for lighter icing and some snowfall. Winter weather advisories have been expanded into eastern Maine and the higher elevations of Massachusetts since yesterday evening.
After the afternoon lull, precipitation will once again fill back in. This is when freezing rain will likely be most prevalent across the region. The area most likely to see freezing rain during this time will be in a zone from northern Massachusetts (mostly at higher elevations) through central Vermont and New Hampshire. This is the time frame when the most ice accumulations may happen as conditions will become more favorable for ice to accumulate rather than melt.
Areas that see primarily freezing rain Saturday into Sunday morning could see upwards of 0.20-0.50 inches of total accretion by Sunday evening, with locally higher amounts possible. This zone is most likely to set up over central Vermont into southern New Hampshire away from the coastal plain. This area is where the most widespread freezing rain may come this evening into the overnight, when a lack of sun will help ice accumulate more efficiently.
While the northern Massachusetts through central Vermont and New Hampshire zone will likely see freezing rain this evening through Sunday morning, areas farther north will likely see their most freezing rain during the day Sunday through Sunday night. This will come as warmer air aloft continues to push northward through the day Sunday.
This will start to switch southern and central New England to plain rain by Sunday morning while northern areas (mainly north of the Lake Winnipesaukee line) will see snow and sleet switch to freezing rain. These northern areas are more likely to see less icing versus southern New Hampshire/Vermont since the freezing rain is most likely during the day Sunday, when the sun is out and makes it more difficult for the ice to stick (the strong late-March sun angle will be working hard behind the clouds).
There will be an elevated power outage threat across Vermont and New Hampshire. 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. Over a half inch is when larger issues begin to arise. A wide portion of northern New England may see at least a tenth of an inch.
With that said, this is not a slam dunk ice storm forecast (if such a thing really exists). While the warm nose will be impressive, the layer of sub-freezing air is currently being shown to be a few thousand feet. This means the cold air layer may be just deep enough to support more by way of sleet rather than freezing rain, or at least sleet mixing with the freezing rain, cutting into icing totals through Saturday night. Also, the freezing rain could be more transitional as opposed to dominant. This would mean a shorter period of freezing rain with more by way of snow/sleet to the north and plain rain to the south.
All of this comes as an impressive warm nose will work into northern New England aloft. This will come as surface features keep colder air trapped at the surface, leading to strong cold air damming. This is highly supportive of mixed precipitation and icing. A deeper layer of warm air over shallower cold air is indicative of freezing rain. With a pronounced and deep warm nose, freezing rain remains the going forecast.
Below: Diagram of cold air damming:
This system will be much less impactful for southern New England, who will see mainly plain rain showers Saturday morning, with isolated activity in the afternoon. Some freezing rain/drizzle will be possible Saturday night as the temperature drops. There still looks to be a large temperature gradient, depending on where the front sets up for the afternoon.
The front will be waffling north and south through the weekend as waves of low pressure pass along it. There remains big bust potential on temperatures across much of southern New England, but particularly south of the Mass Pike this afternoon. Actual high temperatures (and they occur this afternoon) will be determined by the speed at which the boundary moves back southward.
Below: HRRR showing potential temperatures around mid-afternoon today:
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