By James M. Arnold, Weather Specialist
Region – Here is an update as of Monday afternoon, Nov. 24, regarding a possible Thanksgiving Eve snowstorm:
It continues to look like the busiest travel day of the year will be complicated by a disruptive and in some cases a crippling snowstorm. Although there are still a lot of moving parts, it looks like the pieces are coming together as far as the track is concerned. Final thermal profiles are still to be determined, but they should be sufficient to give us a rain to snow situation early in the storm with the bulk of the precipitation falling as a heavy, wet snow. The Wednesday afternoon commute and subsequent holiday travel should be heavily impacted, complicating an already difficult situation. There are four components of this storm that bear discussion. They are:
Precipitation: It looks like the first precipitation should arrive during the early morning hours of Wednesday, likely in the 7:00 to 9:00 A.M. timeframe, although a few scattered and insignificant sprinkles could be seen as early as later Tuesday night. Rain will slowly increase in intensity and begin to mix with snow by late Wednesday morning and change to all snow shortly after noon. Snow will become moderate to heavy at times by later in the afternoon and continue throughout the night before tapering off and ending early Thursday morning, probably in the hours just after sunrise. This will be a very heavy and wet type of snow, that will plaster and coat everything it falls on and it will be extremely hard to move due to its weight.
Wind: As the storm moves up the coast it will be intensifying, and this will create a fairly strong pressure gradient between it and high pressure to its north. While this will not be the windiest storm we have seen recently, it will not have to be to cause damage to trees. Winds will increase during Wednesday afternoon and evening to 15 to 20 mph with occasional gusts into the 30 to 35 mph range throughout the night. This could be enough to break large, heavily snow laden branches off trees if not bring whole trees down with the potential to create scattered power outages and interrupt travel should they fall into area roadways.
Temperatures: The expected temperatures with this storm will begin in the mid to high 30s early Wednesday as the rain begins, but will begin to fall as the storm draws colder air in with intensification. In addition, these storms create their own supply of cold air as the heavy precipitation pulls colder air from higher levels of the atmosphere into the circulation. These factors will serve to offset the lack of cold air in advance of the storm and help to cause a heavier snowfall in many areas. By early afternoon Wednesday our temperatures will sink into the low 30s and should stay there throughout Wednesday night.
Geographic Accumulation Distribution: This storm will be somewhat dependent on elevation for snow. I am expecting the higher ground areas to the north and west of Shrewsbury, such as Paxton, Rutland, Holden, Princeton and points to the north and west to see the deepest accumulations as snow will fall for a longer period of time, perhaps for the entirety of the storm. Accumulations could be in the range of 10 to 15 inches in portions of this area and there could be a few isolated pockets of 18 inches reported. In the Shrewsbury, Worcester, Leicester, and West Boylston areas, accumulations will likely be in the 8 to 12 inch range. Further to the east toward the Route 495 corridor, accumulations will taper off to 4 to 6 inches in the Southborough area and the same holds true for the areas to the south of the Mass Pike, where Northbridge should be looking at 4 to 6 inches as well. The coastal plain, Cape and Islands will see only a slushy accumulation if anything, as rain will make up the most of the storm. Those areas will see a different set of problems as the wind from the east and northeast will pick up to 25 to 35 mph with some gusts to 55 mph possible. With fairly high astronomical tides there is the threat of some significant east facing beach erosion at the time of high tide early Thursday morning.
What’s Next: Thursday will be a transition day from the storm to a partly cloudy and quite breezy day with temperatures holding in the mid to high 30s and Friday will become a nice day with temperatures around the 40 degree make. At this time of year and in this pattern you will be hearing about more storms and rumors of storms, and yes, there is another storm on the horizon for later in the next weekend, but let’s get through this one first.
James M. Arnold is a Weather Specialist working with Shrewsbury Emergency Management Agency; town of Princeton; Worcester Emergency Communications and Emergency Management Agency; Southborough Emergency Management Agency; town of Grafton and Wachusett Mountain Ski Area