NEW YORK (FOX5NY.COM) - Winter is coming. Very soon, the tristate New York area will be dealing with the harshness of the wind, cold, ice, and snow. About this time each year, we try to predict just how severe the winter may turn out to be.
Unlike 5- to 7-day weather forecasting where we are concerned with fronts, pressure systems, and the position of the jet stream, long-range predictions look at more global features that can exist for a period of weeks or even months.
The features you always hear most about area El Niño and La Niña, which get determined by the sea surface temperatures of the eastern Pacific Ocean around the equatorial latitudes. El Niño represents warmer than average temps and La Niña reflects cooler than average. They can be fairly well predicted in advance and may last for many months. Jetstream patterns can be greatly influenced by either of these.
Another factor we analyze is the PDO, or the Pacific Decadal Oscillation, where waters of the North Pacific are either warmer or cooler than average. Also able to be forecasted in advance, the PDO can have an effect on the position of the polar jet stream.
Closer to home, the North Atlantic Oscillation, or NAO, is a shorter-term phenomenon lasting for a period of several weeks. In the positive phase, lower air pressure is observed over the far North Atlantic with high pressure to the south. This usually results in a milder and drier forecast for our area. The negative phase reverses the pressure relationship and tends to produce a colder pattern with the potential for storms to develop along the East Coast.
Another item on the list to consider is the amount of snow cover that has accumulated during the fall season over North America and Siberia. Cold air is dense and eventually has to move southward. The larger the snowpack, the greater the odds are for that cold air to seep down into the United States earlier and last longer.
History also has a role.
"A key to long-range forecasting can be to compare the current pattern with what occurred in similar years," Fox 5 meteorologist Mike Woods said.
This particularly applies to the intensity with regard to solar output. There is a minimum intensity period every 10 to 15 years. So if we look back in time, we can make comparisons to 2009–2010, 1995–1996, 1986–1987, and 1977–1978. Those winters were cold and snowy for the east and particularly the northeast part of the country. 1977, 2002, 2009, 2014 were all el Niño years which we believe will be the case this upcoming season. Above average snowfall was the result for the NYC area with several major snowstorms occurring from nor'easters during the months of January and February.
So let's put it all together for this coming winter.
1. A moderate El Niño leading to a strong subtropical jet stream which can generate more East Coast storms. Supports warm/drier west, cooler/wetter south, near average temps here.
2. PDO in the positive phase, producing a warm bubble in the northeaster pacific. Also supports warmer/drier west and a colder-than-average east.
3. Snow cover currently above average across northern Canada, Greenland, and into Siberia.
4. NAO may come into play starting in January.
This is my overall forecast for New York City:
While we may have cold outbreaks in December into January, the main part of winter will be delayed with the coldest and snowiest periods not starting until later in January and lasting through February. Look for average temperatures to prevail with slightly above average snowfall. Average snowfall for New York City is 28 inches a season. We're predicting 30 to 40 inches for this winter.