When my Nana left Maine in the mid 1970’s to retire to Florida with my grandfather, she used to say some winters in Maine were “open winters”, those where the depth of snow and breadth of cold weren’t so bad. While we’ll have to wait until May to know what this winter was like, there are already plenty of predictions available for what might lie ahead.

The National Weather Service released its winter outlook yesterday which of course receives a lot of press. The outlook from this agency is a probabilistic one. They use a probability system much the same as a chance of showers. On a day where the chance of rain is say 40%, there is enough of a risk to mention this in the forecast, but there is still a large chance, 60%, you won’t see them.

The winter outlook from NOAA should be thought of in much the same way. Those numbers which lean warmer, colder, wetter, or drier only means the forecast is leaning in that direction.

When you look at the winter forecast from NOAA’s Climate Prediction Center you find most of New England is just slightly tilted to a higher probability of a warmer than average winter and on the northern edge of a wetter than average winter.

Remember, this outlook is for December 1st 2015 through February 29th 2016. It doesn’t include a possible snowy and cold March or an early spring after a potentially colder winter.

The pattern assumes a mean storm track into the west coast, with hopefully drought relieving rain which continues across the southern tier before turning up the east coast.

The conundrum for Maine will be whether these storms continue northeast along the coastline or head out to sea. The pattern also assumes the core of the coldest air stays locked up in Canada with fewer arctic outbreaks than last year. This doesn’t mean no snow or no cold, but it’s likely to be a significantly different winter than the past couple.

Highly Changeable
Winters in New England have tremendous variability. In Portland and surrounding areas, we have seen years where not one snowstorm reaches the 8 inch mark and others when multiple storms over 12 inches fall. This clustering of storms is often a result of patterns locking in for 6 week periods. Sometimes the patterns repeat themselves again for another 6 weeks and thus you have three intense months of winter.

Most of the forecasts being issue since August take into account the status of the ocean waters around the globe. While there are other factors in play, the vast expanse of water and its subsequent relationship to the upper level wind patterns makes looking at the state of the oceans in fall necessary to help predict the upcoming winter.

The two maps below show the state of the ocean waters last February followed by where we are as of this week. Notice the enormous changes that have occurred.

While El Nino exists this year, each El Nino cycle is different. The placement of the warm water, the depth of it, and the extent in all directions each play an important role in driving the atmosphere. While the waters off South American might be warmer than average a cold pool of water in the North Atlantic can shift upper level winds enough to have storms hit or miss.

In October and November 2014, no one foresaw the snowiest winter on record in Boston or the deep cold here in Maine. While I expected a very cold February, along with many others, I didn’t imagine or forecast the depth of snow that would pile up in 6 weeks.

Last year’s severe winter snow was quite localized. Much of the western half of Northern New England saw typical or even below average snowfall. It was the cold which was so pervasive across the entire northeast corner of the United States.

On average there are 7 days with an 3 inches or more per year in Portland and surrounding areas. This number has been as high as 16, back in 1996. The timing of any snow is critical to its impact. 4 inches of snow from 8 pm until 1 am has a very different affect than if it occurs 12 hours earlier.

The long term models have El Nino weakening late in the winter and towards spring. Were this to occur, other factors would likely come into play beyond El Nino.

Analogs
Forecasters often use analog winters as a way to see how the atmosphere will perform in a given year. This year meteorologists are using years like 1957-58, 1986-87, 1987-88, 2009-10 and others. The problem with the analogs is this year’s situation isn’t the same as the past, but they can give us an idea for the future.

Last Year’s Predictions
At this time last year NOAA also made a winter prediction. You can see it below. The forecast was good in some parts of the country, but abysmal in the northeast, especially New England. At this time last year there were some signs of a possible El Nino, but this never materialized and was likely a strong piece as to why the forecast didn’t verify.

Predicting the entire winter is difficult. Even with the latest models and fastest computers unforeseen or less understood factors can change these predictions. Each month I try to outline my own best thoughts about snow and cold for the upcoming 4 weeks. This shorter term look at the forecast tends to have a higher rate of accuracy. You can follow me on Twitter @growingwisdom for more details and to comment.

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