It's finally here! After weeks of looking over global computer models, and climate records from previous years with similar conditions going into the winter season, I am ready to release my outlook for this upcoming winter.
For starters, let's establish a ground rule. Given that this outlook covers such a broad timespan, This forecast is largely based on global weather patterns, and microscale events that shape our day-to-day weather simply cannot be taken into consideration this far away. Therefore, this outlook does not forecast specific snow storms, cold snaps, etc., but rather, what we can expect this winter to be like as a whole. With that being said, let's get started!
December & January: 3°F to 5°F above average
February & March: 2°F below average to 1°F above average
The first thing to consider when making a winter temperature outlook is the El Nino-Southern Oscillation (ENSO) cycle. This is essentially just a fancy way of referring to the ocean temperature of the Pacific Ocean between the West Coast of South America and Australia. The ENSO cycle has two phases: El Nino and La Nina. During an El Nino phase, water temperatures are above average, while they are below average during a La Nina cycle.
Now, why exactly are we concerned with ocean temperatures in the eastern Pacific Ocean? Because it is these temperatures that determine the overall trajectory of the jet stream, which functions as the highway that major storms travel along, as well as the dividing line between cold air (to the north of the jet stream) and mild air (to the south of the jet stream). This season, we are looking at a moderate El Nino pattern.
As we can see from the graph above (courtesy of NOAA), an El Nino pattern keeps the frigid temperatures associated with the Polar Jet Stream to the north of Central New York. That's not to say we won't have any cold snaps, we will, but in general, expect a warmer winter than average, especially during the first half of the season. As winter progresses, however, we can expect the temperatures to become slightly colder. This prediction is attributed to long-range models suggesting the North Atlantic Oscillation (NAO) transitioning from a positive phase to a negative phase as the season goes on. The NAO is separate from El Nino and La Nina, as the NAO takes place in the Atlantic (hence the name), and has to do with atmospheric pressure, rather than ocean temperatures. Similar to El Nino and La Nina, NAO effects the direction of the jet stream. A negative phase causes the jet stream to wrap around the East Coast of the US, allowing Arctic air to infiltrate Central New York. On the other hand, a positive NAO keeps the cold air to our north.
With all of that being said, I'll conclude the temperature section by stating that specific spans of mild and cold periods throughout the winter are determined by the interaction of the ENSO and NAO cycles. These factors are too complex and specific for weather models to pick up on this far away, but by looking at the general cycle patterns of each, we can have a broad idea as to what the temperatures will be like during this winter.
December & January: 33" (average: 40")
February & March: 52" (average: 57")
Forecasting snowfall for Central New York is notoriously tougher than temperature predictions. This is because while cold air masses and air masses effect entire regions of the country, snowfall is a much more localized phenomenon, especially here in Central New York. This is primarily due to lake effect snow, which can dump huge amounts of snow over a very small area. For more information on lake effect snow, click here. With that being said, lake effect snow is the primary component of the snowfall forecast. As of October 3rd, NOAA reports that the surface temperature of Lake Ontario (the source of our lake effect) is running over 6°F above average. That is significantly above average, and will continue to remain above average for at least the next several months.
Although a warmer lake temperature allows for more powerful lake effect snow events, I still predict that we won't see above average snowfall because of the prevailing wind direction, brought by El Nino and a positive NAO (at least during the beginning of winter-the most active time for lake effect), will keep the bulk of most lake effect snow events just north of the Holland Patent school district. Areas such as the Tug Hill Plateau and western Adirondacks will face the brunt of this lake effect, and therefore they will likely see average to above average snowfall during December and January.
Synoptic snow refers to snow that comes from literally any other type of snow storm besides lake effect. It goes without saying that synoptic snow is the other component of my snowfall forecast. Given the direction of the jet stream, as determined by the ENSO and NAO cycles, I predict that some synoptic storms that impact our area will track to our west, Whenever winter storms track to the west of Central New York, they bring milder air, and we get a cold rain event instead of snow. To learn more about how the track of a storm determines if we get rain or snow, click here. It is because of this that I predict we will see slightly below average snowfall during the second half of winter, even with colder temperatures predicted.
I hope you have enjoyed reading the 2018-19 Winter Outlook. If you have any thoughts or questions, comment below!