SYRACUSE, NY (WSYR-TV)
The 2020-21 Storm Team Winter Outlook is calling for above normal temperatures in Central New York from December through February. There will still be some ‘cold’ spells during the winter, most likely after New Year’s Day.
Snowfall is expected to end up below normal for Syracuse somewhere between 95” and 115”. Normal snowfall during winter in Syracuse is 123″.
Those are the main takeaways. What follows is a more in-depth look behind our reasoning.
We think La Nina will end up the main driver of the weather across the United States this Winter
La Nina is the cooler than normal equatorial waters in the Pacific Ocean. That type of set up typically leads to a jet stream in the United States in winter that focuses warmth in the East, especially the Southeast.
The biggest question for us is just how cool these waters end up over the winter months which ultimately defines how strong La Nina gets this winter.
The latest update from the NOAA (National Oceanic and Atmospheric Administration) indicates that those equatorial waters are cold enough to be classified as ‘moderate’ La Nina and very close to ‘strong’ There are also signals that this may be the peak in intensity for the winter season.
For Syracuse, the stronger the La Nina (the cooler the Pacific temperatures) in general the lower the amount of seasonal snowfall.
Another clue that has gotten a lot of attention in meteorological circles in recent years is fall snow cover in Siberia.
When this snowpack grows quickly in the early fall, the theory follows that changes take place in the atmosphere to cause a weaker Polar Vortex in the Northern Hemisphere which makes it easier to drop south into the Eastern United States causing extended periods of bitter cold and snow.
This fall, however, the early season snowpack in Siberia is below normal which favors a stronger Polar Vortex, one that would remain up near the North Pole, limiting arctic air into the United States during the winter.
One ‘conditional’ factor for our Winter Outlook is what happens when Novembers are much warmer than normal.
We certainly saw unusual warmth earlier in the month with a string of days in the 70s in Syracuse and if this month ends up as one of the warmest November on record there are some potential clues to the winter weather.
In the past, when November temperatures ended up more than 4 degrees above normal, five out of the six years had snowfall below normal, below 100 inches.
In fact, our two least snowy winters since records have been kept at the Syracuse airport (2001-2002 and 2011-12) both occurred after very warm Novembers.
Even though November is certainly looking like it ends up with above normal temperatures, we won’t know exactly how warm for another ten days. If we end up at or above that 4-degree threshold by the end of the month that would give us more confidence of a winter with less than 100” of snow in Syracuse.
Keep in mind, while we are forecasting the overall three-month average of temperatures for December through February to end up above normal that doesn’t mean we can’t have short bouts of cold weather. When looking at all the La Nina winters since 1950, 21 out of 22 had at least one day in the winter with a temperature below zero.