Below is a graphic displaying 1000mb to 850mb thicknesses. I have highlighted several key areas which will be of extreme importance as we move through the weekend and into the beginning of the work week. The explanation of the highlighted areas and their importance will be discussed below the image:
The red circled areas are areas of high pressure. Notice how there is a big area of high pressure just to the north of the United States across central Canada and a huge area of high pressure across the southern portion of the United States. In between these areas of high pressure we have our frontal boundary, an Arctic cold front and this, along with the area of high pressure across Canada is allowing for brutal Arctic cold to work here in to New England and the flow around the high pressure is allowing for this cold to be maintained. The area of high pressure across the southern-tier of the United States is allowing for this front to stall across the extreme northern-tier of the country and just south of New England.
The blue circled area is where not only our frontal boundary is positioned but this is where the mid-level jet stream is located as well (although not pictured here). Notice the green shadings within this circled zone? This is moisture associated with the boundary and this moisture is streaming across this portion of the country all the way from the Pacific! As long long as this pattern configuration is in place Pacific moisture will continue being streamed all the way here into New England. As we eventually move into Sunday the pattern will also begin to allow more in the way of Atlantic moisture to work into the picture as well and this is when some areas could receive some significant snows. What our focus will be on over these next several days is pieces of energy developing and riding along the stalled out boundary in this highlighted area. Lift + moisture = precipitation and we will have plenty of moisture to work with so add in any extra lift and we will be looking at the potential for quite a bit of precipitation...but the million dollar question is, where will the axis of highest amounts occur?
Now we will take a look at each of the upcoming days with a bit of detail and what we could potentially expect.
Saturday
For the most part, Saturday and Saturday night is looking to be the "quieter" of the days between tomorrow and Tuesday. Computer forecast models bring a weak piece of energy through the jet stream tomorrow and have some light moisture associated with the energy. As of right now it appears the track of this system will be more through central and northern New England, meaning the highest degree of lift will be across these areas. If this track verifies it will be areas north of the MA Pike up through central VT, central NH and into southern ME which see the periods of the heavier snows. Across these areas 1-3'' of snow will certainly be possible within this area.
South of the MA pike across southern MA into CT and RI, the degree of lift is not expected to be as strong with this track so these areas should remain outside of the heavier snows. Still, some locations may pick up an inch or so of snow, especially across the higher terrain.
Sunday
As we move into the overnight hours of Saturday into Sunday, this is when things will begin becoming more interesting. By this time more in the way of Pacific moisture will have spread into the region and computer forecast models are hinting at some stronger pieces of energy moving through aloft. Higher moisture content and stronger lift indicate periods of moderate to heavy snows will become much more common overnight Saturday through much of the day on Sunday. While it will not be snowing this entire time everywhere, we will see multiple periods of moderate to heavy snows throughout this time. We will not be seeing a widespread precipitation shield which encompasses a large area (like we see with coastal storms), rather we will see numerous bands of snowfall which will likely be more narrow in nature. This means that you can have an area where snow is coming down extremely heavy, however, you go just several miles away and nothing is occurring. It is a situation like this which will make forecasting snowfall totals EXTREMELY difficult. Between overnight Saturday into the overnight hours of Sunday some of the hardest hit areas could receive as much as 6-10'' of snowfall and perhaps even some higher amounts in some spots. On the other hand, areas who don't see much action may be luck to get 2-4'' and the axis between these high and low amounts could end up being only a matter of miles!
Monday
Moving overnight Sunday into Monday this is where the forecast becomes even more complex and that is because we are still a little far out. However, computer forecast models develop a stronger area of low pressure right along the stalled out front. This is where we will begin to see more in the way of Atlantic moisture become involved as well and this is when we could see even higher snowfall totals. The track of this low and the strongest lift and moisture will all depend on the exact positioning of the stalled out boundary. This is something which will be sorted out over the next 24-48 hours. With this system we may also be looking at a more widespread precipitation shield meaning a much more widespread area is hit harder...as opposed to only a few select locations. This system will have the potential to yield upwards of 9-15'' of snow with lesser amounts of 3-6'' across the areas outside of the heaviest precipitation. This portion of the forecast though is much more tricky at this time.
Summary
Between tomorrow and Tuesday it is not out of the question that some spots could pick up anywhere from 12'' to even 20'' of snowfall depending on how everything aligns and comes together. Just keep in mind this is not going to be a uniform system where we are looking at uniform totals across a widespread area. The difference of even 5-7 miles could be the difference between 6''+ of snowfall totals. This can't be stressed enough. With this in mind, I feel creating a snowfall map is not the right thing to do at this time as amounts may vary widely across such a small area.
How to Prepare?
Just keep listening to all forecasts and all the updates provided. Just keep in mind that on the higher end of the scale you could see as much as a foot-and-a-half of snow and on the lower end you may only see a half-a-foot of snow. Always prepare for what the higher end of the scale may bring as it's better to be over-prepared than under-prepared.
Beyond Tuesday
Looking ahead to the end of the week and next weekend we could be looking at some of the coldest temperatures we have seen in quite some time as computer forecast models indicate Arctic air plunging directly into New England but we will worry about this as we get closer.
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