I can say every year that this is a hard forecast, but that has become redundant. There is no “easy” long range forecast. So with that in mind, onto the one for the upcoming winter.

OVERVIEW

The greatest factor in this winter’s weather is likely to be the ENSO phase, which is now La Nina (central-east based), with this expected to be the case through the winter, including March. I have factored in the pattern that has been ongoing since about mid October into late November, with La Nina in place, and this has given me some clues. Other factors influencing this long range forecast are the QBO (Quasi-biennial Oscillation), stratospheric winds in the tropical regions, in their westerly phase at this time with this likely to continue through winter as well. Other significant factors in place include below normal Arctic sea ice and below normal Siberian early season snow, but above average snow cover in North America. We are just coming off a solar minimum (low sunspot activity) and entering the upswing phase, although the activity overall will continue on the low side for the winter. Three wildcard factors: 1) Anomalous warm water in the northeastern Pacific Ocean. 2) Anomalous cool water pool in the central Pacific, northwest of Hawaii, related to a Pacific Decadal Oscillation (PDO) that has been somewhat neutral but is having a trend to positive, which is a phase featuring warmer water off the US West Coast and cooler water in the central Pacific. 3) Madden-Julian Oscillation (MJO), which is a measure of movement of regions of enhanced and suppressed tropical rainfall, has been in a very weak phase for some time, and indications are that this will continue for a while, but this index can be somewhat unpredictable and can become more of a factor with little warning, so its impact may become more influential as we move into and through winter. Further factors which we can get an idea of based on the above are less predictable in the longer term, such as the Arctic Oscillation (AO) and the North Atlantic Oscillation (NAO), will be factors as well, but I can’t say with any confidence that I can tell what phases these will be in as we go through the winter. What I can say is that the factors previously mentioned weigh toward a frequently positive phase for both AO & NAO. The positive AO is a polar vortex (PV) that is strong and rather tight to the pole, keeping the coldest of the arctic air bottled up. However, the lack of sea ice is a catalyst for causing the PV to become unstable at times, potentially sending the AO into intervals of negative phase. This will be something we’ll have to watch for. Another factor in helping to determine this is sunspot activity. With the solar activity, while still not far from its relative minimum, starting to increase, the chance of a burst of energy from the sun increases, and it has been shown that a strong pulse of energy from the sun can correlate with keeping the AO positive. Will the low sea ice and increasing solar activity have to “fight it out” at any point? We can’t know that in advance, only monitor for the possibility. Similarly, the NAO would like to stay in its positive phase (little or no high latitude blocking) under many of the conditions mentioned above, but a disruption of the PV, or the MJO heading into certain phases in a stronger cycle can have an impact on that, and we could find ourselves with one or more periods of negative phase of NAO, which would present a blocking pattern and potentially increase the chance for colder weather and winter storms. Again though, no guarantee that this happens at any particular time. I can look ahead and say that I can see the potential for at least a brief episode of something like this after the first week of December, but would it result in anything that would make us remember the early part of winter 2020-2021? Only time will tell… As always, other factors that I have not even mentioned will be monitored and I can talk about those in the day-to-day comments if and when needed. So with all of the above in mind, what follows is my best shot at month-to-month characteristics for the winter.

DECEMBER
As goes November, so goes the winter? I said this last year, and based some of my forecast off it. That only worked out briefly, then was a lost cause. So will I abandon that thought this year? Well, not necessarily. Last year, a very cold November was followed by a cold to seasonable early to mid December, early snow, and then winter making an exit just as the solstice announced the actual beginning of winter. That said, I do think the pattern that we have been in from mid October well into November does hold some significant clues as to what December (and even beyond) will be like. Since it took place as we got into La Nina, and that La Nina will be persisting, that alone gives it some credibility, especially since the westerly QBO is also likely to continue, and these are 2 of the larger factors that drive the pattern at this time. So what does that mean for December? Well, Canada has been pretty cold, and we’ve seen this go into the western US several times, and punch its way into our area a few times as well during the course of autumn, and I think this general pattern is still going to be in place as we head through the final weeks of autumn and into the first couple weeks of winter, astronomically, of course adjusting for climatology based on the calendar. The wild card for December is MJO. There are some signs recently that as we get into December by several days that the MJO may strengthen and move into a phase 6/7 cycle. MJO can be a little more favorable for wintry weather in the Northeast when it is in phase 7 early in the season. Add in the possibility of temporary PV disruption as we continue with good snowcover in Canada and low sea ice in the Arctic region, and our pattern could find itself favorable for some early ice/snow opportunities here as we get toward the middle of the month. Odds would favor the stronger long term pattern of milder with brief cold shots taking back over before the end of the month, as the larger drivers would be superior and eventually win out. But will that episode of wintry opportunity be enough to produce some significant snowfall? I say yes it will, and while this is a risky call that can make my winter forecast look bad early, I’m going to lean that way. Temperature: Near normal, mildest relative to normal late in the month. Precipitation: Near to above normal, most active in the middle 20 days. Snowfall: Above normal, but not by that much.

JANUARY
The first month of 2021 should display the general characteristics of the pattern leading up to winter, as the large scale drivers that are strongest become most dominant (La Nina, QBO, AO). This pattern would be mild overall, but with short-lived and sometimes sharp cold shots. Several times during the month we would be the pathway for disturbances along the boundary between a fairly cold Canada and an persistently mild to warm Southeast as the La Nina driven ridge dominates that part of the US. The polar jet would be spending more time north of the border with occasional inroads into the northern tier of the Lower 48, including New England, but more often west of here. A weakened version of a Pacific jet stream would drive the primary storm track from the West Coast east northeastward across the country, sometimes north of, sometimes over, and sometimes south of New England. And while I don’t think it will be a gangbusters storm pattern, we will see our share of “events”, many of which would be wet versus white, but a couple or a few that could be on the messier side. Nevertheless, the first 2 months of winter should help us take steps to getting out of drought, but falling short of getting us completely out of it as it will take time to overcome the long term precipitation deficit. Temperature: Slightly above normal.
Precipitation: Slightly above normal.
Snow: Below normal.

FEBRUARY
La Nina peaks, westerly QBO dominates, PV is strong and tight to the Arctic, NAO is positive, MJO probably continues its overall trend of being not a big factor, and this should allow the Southeast ridge to be dominant, keeping that battle zone we had been in for much of the winter so far further north, and fooling everybody into thinking winter was ending early……… Temperature: Above normal.
Precipitation: Below normal.
Snow: Much below normal.

MARCH
What happens when you wind something up really tight? Eventually something has to give. All you need is a weak point or some kind of trigger. Canada will have spent a good amount of autumn and winter building a solid snow pack and holding a fair amount of cold air, that at times finds its way here but for long stretches is locked up there or in the western US thanks in part to a ridge of high pressure in the Southeast. Most of the indicators are also that the cold in Canada will extend through Alaska, and often when Alaska has a cold anomaly, the eastern US trends warmer. What may happen in March would possibly be triggered by a weakening and shifting of the warm pool of water in the northeastern Pacific Ocean, basically a PDO readjustment, along with the normal shifting of the behavior of upper air patterns as spring approaches, leading to a better chance of high latitude blocking which can help trigger a disruption of the PV. We’d likely see a period of ridging across Alaska, warming that area up, and flushing cold air southeastward through Canada and into the north central and northeastern US, and a southward shift of the Pacific jet as the Southeast ridge gives ground as the La Nina shows its first signs of weakening. This would shift our pattern to a colder and more active one, opening the door for a late burst of wintry weather that had been missing during the heart of winter. I realize this is a gamble, but given the inherent uncertainty in forecasting that far in advance, an educated guess leads me to this conclusion. If we get late snow, at least the sun angle will be higher and the days will already be noticeably longer, easing the impact of late-season cold and snow. Temperature: Below normal.
Precipitation: Above normal.
Snow: Much above normal.

WINTER SEASON OVERALL
Temperature: Slightly above normal.
Precipitation: Slightly Above normal.
Snow: Near to slightly above normal.
-Boston 45-50 inches
-Worcester 60-65 inches
-Providence 40-45 inches
-Hartford 45-50 inches