A More Active Pattern

10:00 PM

This rather long introduction will serve as a slight in depth discussion as to how I came up with my forecast.

So far this month, it has not seemed like we are in meteorological winter as temperatures have been above average for the most part. There has also been a lack of snow so far this month, especially in Southern New England(Not entirely uncommon). Central and Northern New England have been also lacking snow, along with above average temperatures.

The pattern that we have been in for the past two weeks is about to undergo drastic changes. Changes that will likely bring colder temperatures, and an increased possibility of snow. This is all in response to blocking upstream moving into a favorable position, or what is known as a west-based negative North Atlantic Oscillation(NAO) in the meteorological world.

A west-based NAO is known to increase storminess and cold along the east coast. The combination of moisture and cold air leads to snow. However, the depth and intensity of the cold determines how long precipitation can stay in the form of snow, especially along the coast line as ocean temperatures are quite mild. There is also the common question of how much moisture is available. All of these variables are greatly influenced by the track of a low pressure system, which is one of the most crucial parts of a forecast.

You might ask how we can determine a storm track several days out, as well as the amount of cold air and moisture available. The simple answer is computer models simulate future weather, and there are many different models out there. The problem with models is that their solutions aren’t always perfect, and the solutions can vary greatly from different models. These solutions can also change day to day, especially when the event or events are several days out.

The models aren’t the only tool out there for meteorologists, which is why I brought up the NAO earlier. There are other global indices that can affect our pattern, which I won’t get further into as you might get put to sleep if your not interested. If you are interested in a good read, feel free to check out this link. http://www.nc-climate.ncsu.edu/climate/patterns/NAO.html

Now onto what the short term future may bring, which will extend out to next week.

For the Boston area…

The first batch of precipitation comes through Sunday afternoon and ends Monday morning. It will likely start off as snow showers, then transition over to sleet, then over to all rain overnight Sunday. Snow accumulations of a coating to an inch is expected for this batch.

The second storm looks to be much stronger than the one coming through Sunday night. At this point it looks like to impact this region Wednesday and Thursday. Since we are quite far out, and since model guidance is all over the place in terms of a solution(Where does the storm track)(snow vs rain), I will revisit this storm on Monday.

For the Northeast Kingdom of Vermont…

The first batch comes through Sunday night, and lasts till about noon on Monday. Enough cold air will be around to support all snow. The models are currently trending toward higher precipitation amounts as we get closer, which lowers my confidence. The reason my confidence lowers is because whenever a model or several models trend one way or another, it is necessary to keep a close eye encase the model decides to trend back. In this case, the model may trend back to less precipitation amounts. At this point I believe Several inches of snow are possible.

The second storm impacts this region Wednesday and Thursday. It should be mostly snow again with this storm. The question again is where the storm tracks will determine how much snow we receive.

The ski resorts of Northern New England should fare well with these two systems, so there will be plenty of snow over winter break.

Be sure to check back for future updates.