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Spring Storm Incoming to New England: Impacts, Timing

As the system moves northeast toward New England, interaction with the southern stream will help spawn a secondary low somewhere south of New England. This low will strengthen and become the primary low. This system will likely slowly crawl along in the Gulf of Maine or even retrograde westward for a time, leading to a prolonged event as blocking to the east will lead to a slow departure.


The storm will likely track over Cape Cod, which is an ideal setup for rain and mixing in southern New England and snowfall across the mountains. This is not just true because it's spring, if this track occurs in January, it would be a similar result.



ALERTS



TIMING


From Tuesday afternoon through Wednesday morning, rain and snow showers will remain generally light and scattered around with Connecticut, western Massachusetts and southern Vermont seeing the most widespread precipitation during this time. The storm will have dry air to battle initially, which will make the precipitation slow to begin for much of the region.


Expected weather Wednesday morning:


Heading into Wednesday evening, rain and snow showers will fill in, become steadier and gradually move northeastward into the northern tier and Maine. At this point, there will likely be snow falling across the Green and White Mountains, rain and sleet across southernmost New Hampshire and northern Massachusetts with plain rain continuing across the lower elevations of southern New England.



Throughout Wednesday night, the rain/snow will likely gradually drop southward and from higher elevations to lower elevations. By Wednesday night, the secondary low will have become the primary low and will be strengthening. This will allow snowfall rates of 1-2 inches an hour where snow is falling. Where rain is falling, this will allow for periods of moderate to heavy rainfall.


Expected weather Wednesday evening (1st image) and early Thursday morning (2nd image):


As the low continues its slow crawl eastward, snow and rain showers will continue through Thursday. Both snowfall and rainfall rates will likely begin to ease up, but accumulations will still continue. The storm has been taking a northward trend as of late, this may allow a dry slot to get into southern and central New England. This would lead to very light snowfall and rainfall rates in these areas on Thursday. How far north a potential dry slot gets will be dependent on the final track.


Expected weather around midday Thursday:


Rain and snow showers will likely persist through Thursday night as the low meanders around in the Gulf of Maine. The snow showers will generally become lighter and more scattered as Friday goes on, with the most activity by Friday afternoon limited to the mountains.


Expected weather around 5am Friday:


SNOWFALL


As mentioned in the "timing" section, intense snowfall rates of 1-2 inches an hour will be possible Wednesday night from the foothills of northern New England through the mountains. Mesoscale banding is likely to set up across northern New England, which are narrow bands of intense snowfall. These bands of snow will be needed in order to receive the amounts of snow expected.


A majority of the accumulations will likely occur overnight Wednesday into Thursday morning. This is when the heaviest snowfall rates are expected for New Hampshire and Maine. This will aid in the higher snowfall totals occurring as daytime accumulations can be hard to come by with the strong sun angle. At Night, this feature is naturally lost.



With that said, the jackpot zone with this storm continues to look like it will be across the White and Maine mountains, with the border between New Hampshire and Maine seeing the most. A wide swatch of a foot or more of snow is looking likely in these areas, with the New Hampshire Lakes Region also potentially getting into the foot plus if the track is right.



When all is said and done, much of northern New England will likely have seen at least 6 inches of snow, with the exceptions being the Champlain Valley, the New Hampshire Seacoast and northern Maine, where lesser amounts are expected due to lighter snowfall and mixing issues.


We're still watching for the possibility of a very sharp cutoff in snow totals across southern New Hampshire and along the immediate Maine coastline. The final track of the storm could push this cutoff either north or south, so it's something to watch closely.


Probability of snow accumulating at least 4 inches. You can see probabilities drop from 90% just north and west of Manchester to 30% by the coast:


Southern New England's snow will likely be highly elevation based with the northern Berkshires and northern Worcester Hills seeing the most snow, which will be far less than what is seen in northern New England.


Bust potential comes from the fact that it is now April. There are a plethora of things working against snowfall including potential mixing, low snow ratios, warm ground conditions and a strengthening sun angle. At this point, heavy snowfall rates do look to overcome much of this, but there are limiting factors that could bust snowfall amounts.


The areas with the greatest potential to underachieve will be the Green and White mountains. The area with the greatest potential to OVER-achieve will be southern New Hampshire. As always, the final track of the storm will play a large role in where the heaviest snow totals set up.


RAINFALL


This storm will be moisture-loaded. While this moisture is wrung out as snow in the north, it will be wrung out as a soaking rain for much of southern New England. A widespread 1-2 inches of rain is likely across all of southern New England. With this rain expected to fall over the course of 24+ hours, flash flooding is not much of a concern.


River flooding will need to be watched as several rivers could reach minor flood stage. The typical problem rivers could reach moderate stage, namely the Pawtuxet River at Cranston, Rhode Island. Overall, the flood threat isn't all that high.



WIND


With a strengthening storm passing into the Gulf of Maine, winds will become gusty. Winds will pick up as Wednesday goes on and likely peak overnight Wednesday into Thursday morning for most. Winds will remain gusty all day Thursday. A low-level jet with winds of 70-90mph will cross southern and central New England. As always, the question becomes how much of this can reach the ground?



Just about all of New England will have a chance to see at least 40mph gusts with the coast seeing gusts up to 50mph. Some of the higher elevations of southern New England could see some gusts over 50mph. A downslope wind event is expected in the Berkshires and along the spine of the Green Mountains.


A narrow corridor of 60mph gusts are possible in these areas as a strong low-level jet looks to develop over this area overnight Wednesday to Thursday. High wind watches are in effect for these areas. These winds will likely cause whiteout conditions at times.


850mb (about 4,700 feet above sea level) winds early Thursday. You can see a narrow band over the southern Green Mountains and Berkshires (tan color). This will likely cause a downslope strong wind event:



POWER OUTAGES


Power outages will likely be a big issue with this storm. Snow will be of a heavier and wetter variety for most. This snow will stick to the trees and likely cause broken branches and fallen wires. The one piece of good news here is that areas in the mountains, where the most snow is expected, will likely see a drier snow develop Wednesday night. Still, outages are likely. The gusty winds will only exacerbate the conditions, especially in the Green Mountains.



COASTAL FLOODING


Eastern Massachusetts will face the highest coastal flooding threat. A prolonged period of easterly winds and building waves in the Gulf of Maine will likely result in widespread minor coastal flooding with some pockets of moderate flooding possible. This comes amid a general 2 to 3 foot surge. Minor coastal flooding and moderate splash over will be possible across the entire New England coastline. Tides are not astronomically high, which will help the situation.


Wind direction and speed around the Thursday morning high tide:


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