NYC Winter Forecast 2023-2024: Warm start, volatile and active finish
The Winter of 2023-2024 will begin with warmer than normal temperatures and less snow than average in NYC. As the winter goes on, the weather is expected to become increasingly volatile. While temperatures may average near or slightly above normal, it is likely that NYC will see at least a few snowstorms and periods of colder than normal air. NYC’s 30 year average annual snowfall is 28.9″, and we expect slightly above average snowfall during the upcoming winter season.
Seasonal weather forecasting is one of the most challenging aspects of meteorology. It involves understanding several complex factors and detailing an intricate balance of mechanisms that are driving the weather pattern across the globe. We have been piecing together ideas for this upcoming winter since the Spring of 2023, and we are excited to finally have a finished product to share with you.
Within this forecast, we’ll paint a picture of the atmosphere and what it’ll be doing over the next few months based on several global and hemispheric oscillations, conditions, and phenomena. This will lead us to conclusions which we believe will be the guiding forces for us during the seasons ahead.
This forecast will be a bit more complex than our usual posts. We’ll do our best to explain what everything means and we have several videos coming in the next few days to break it all down, too.
ENSO (El Niño Southern Oscillation)
Anticipated ENSO Conditions: Moderate to Strong El Niño
The El Niño-Southern Oscillation (ENSO) is an irregular periodic variation in winds and sea surface temperatures over the tropical eastern Pacific Ocean. ENSO conditions are one of they key drivers to the Winter pattern, and can often be broadly referenced as “tropical forcing”.
Tropical forcing more specifically refers to concentrated areas of showers and thunderstorms, otherwise referred to as convection, in meteorological regions of the tropics. This convection, most frequently observed in warm and moist climates, releases latent heat that then rises up into the atmosphere, forming ridges of higher atmospheric air pressure.
The equatorial waters of the Pacific Ocean that comprise the ENSO regions breed a great deal of thunderstorm activity, which then accordingly results in atmospheric ridging and subsequently moves downstream. This balances the atmospheric regime. In a general sense, the more anomalous the positive sea surface temperatures, the more convection that can then exert a stronger forcing mechanism on the adjacent regions of the atmosphere, reverberating throughout the globe.
Almost all forecast model guidance now agrees that we will experience moderate El Niño conditions during the upcoming winter. El Niño conditions are observed when warmer than normal temperature anomalies exist in the aforementioned tropical regions of the Pacific Ocean. El Niño events typically result in active, warmer weather across the United States as a whole.
SSTA Analysis (Sea Surface Temperature Anomaly)
The ongoing El Niño event is expected to continue to remain in control through the first few months of the winter. Forecast models suggest that sea surface temperatures in these regions could warm even further, with the El Niño event trending towards borderline “strong” intensity. Meanwhile, cooler waters are expected to remain in place off the West Coast of the USA with warmer waters in the North Atlantic. The combination of these factors leads to increasing confidence in a volatile pattern by mid to late winter with the possibility of high-latitude blocking episodes.
Using a weighted analog set with years featuring similar conditions from the past, we are able to compile an analog set of the SST anomalies in the Tropical Pacific. This analog set is important. It helps us to understand where we are heading during the winter ahead and how global circulation patterns may behave. Having confidence in the orientation of SST anomalies in the Tropical Pacific is a key part of the winter forecast and serves as a foundational piece of the forecast as a whole.
The Quasi-Biennial Oscillation (QBO)
Prediction: Easterly QBO
The Quasi-Biennial Oscillation, or QBO, is a measure of zonal winds in the stratosphere (the level above the troposphere, where we experience most of our weather) that typically oscillate between westerly (positive) and easterly (negative) phases, every 12-24 months. The QBO in an easterly phase tends to promote a weaker polar vortex in the stratosphere, resulting in a propensity for more stratospheric warming events during the winter months (allowing high latitude blocking and -NAO episodes to flourish). The QBO in a westerly phase tends to allow a stronger polar vortex to form, limiting high latitude blocking and resulting in a more positive AO and NAO phase during the winter months.
The QBO is currently in a easterly phase, suggesting the possibility of increased high latitude blocking events and polar vortex disruptions during the upcoming winter.
The North Atlantic Oscillation (NAO)
Prediction: Neutral to Negative (-) NAO on average, especially from mid winter onward.
The North Atlantic Oscillation (NAO) is an index based on the surface sea-level pressure difference between the Subtropical (Azores) High and the Subpolar Low. The positive phase of the NAO reflects below-normal heights and pressure across the high latitudes of the North Atlantic and above-normal heights and pressure over the central North Atlantic, the eastern United States and western Europe. The negative phase reflects an opposite pattern of height and pressure anomalies over these regions.
A -NAO has historically been correlated to stormy and cooler weather in the Northeast United States and the NYC Metro region especially during the winter months. The forecast by most guidance going into the upcoming winter is for a neutral to slightly negative NAO. Some seasonal model guidance has also suggested the possibility of more substantial -NAO blocking regimes during January and February.
Still, it’s hard to pin down exactly how this -NAO blocking events will transpire. When -NAO blocks form, they tend to dislodge arctic air southwards towards NYC and also slow down the atmospheric pattern to allow the development of larger storms. We will have to wait and see how the high latitude blocking regime plays out as it could offer windows of opportunity for both cold and snow.
The Pacific Decadal Oscillation (PDO)
Prediction: Negative (-) PDO on average
The Pacific Decadal Oscillation (PDO) is a long-term ocean fluctuation of the Pacific Ocean. The PDO waxes and wanes approximately every 20 to 30 years. When SSTs are anomalously cool in the interior North Pacific and warm along the Pacific Coast, and when sea level pressures are below average over the North Pacific, the PDO has a positive value. When the climate anomaly patterns are reversed, with warm SST anomalies in the interior and cool SST anomalies along the North American coast, or above average sea level pressures over the North Pacific, the PDO has a negative value (Courtesy of Mantua, 1999).
The PDO has recently been strongly negative and is expected to remain that way for the majority of the upcoming winter. Cooler sea surface temperature anomalies are forecast to remain in place off the coast of the Western United States and into parts of the Gulf of Alaska during the majority of the upcoming winter.
Analog Analysis & Other Factors
The importance of analogs in a Winter Forecast has been long debated and discussed. How much should a forecaster weigh what happened in the past against what is happening currently? How can we utilize past events when the atmosphere is almost certain to behave differently each time, especially given the difference in global weather when compared with weather events from the 1950’s and 1960’s?
For us, each winter is different. This year in particular, the number of analog years that fit the set of conditions and the overall progression of the atmosphere is very slim. There are simply very few years that featured a moderate El Niño coming off a three-year La Niña (2020, 2021, 2022) with similar stratospheric and tropospheric evolutions across the globe.
With that in mind, we decided to weight the analog years in our forecast very carefully, taking only the stronger year(s) and blending quickly downward toward the weaker analogs. We’re comfortable with our analog composites that were presented and have factored them into our forecast as we typically do. Think of them as a piece of a much larger forecast puzzle.
When we take the individual pieces of research and compile them into one organized forecast, we can begin to see the ebbs and flows of the winter ahead, as they should be, according to our very best analogs and subset of current and past conditions. This winter, we are confident in our month-to-month composites and have indicated moderate to high confidence on each month.
Below, we break down each month’s temperature and anticipated precipitation trends. While precipitation maps aren’t included (lower confidence), we do discuss precipitation patterns and potential within each individual month’s breakdown. Please keep in mind that this forecast is focused on NYC, but national trends are discussed as well.
December 2023
Much of December is expected to be characterized by warmer than normal temperatures in the Eastern United States. Precipitation, while much lower confidence overall, is expected to average near or slightly above normal in NYC as a result of an active jet stream. With warmer temperatures in place, opportunities for snowfall in NYC proper will be slightly less than usual (our first snowfall typically comes sometime in late December).
January 2024
The weather pattern will become much more volatile in January, owing to the presence of high latitude blocking. These blocking ridges of high pressure will occasionally dislodge cold air southward towards the NYC Metro area, resulting in bouts of wintry weather and the potential for snowfall. Overall, temperatures will average slightly warmer than normal for the month and precipitation is also forecast to average slightly higher than normal as well.
February 2024
An active and volatile weather pattern will remain in place during the month of February. Again, temperatures are forecast to average slightly above normal in NYC for the month. An active jet stream and precipitation pattern will lead to multiple opportunities for storm systems and further potential for winter weather and snowfall.
Winter Summary
A near or slightly above-normal temperature profile is expected this winter in NYC, with colder risks increasing as the winter goes on, after a warm start. Precipitation is forecast to average above normal for the winter months.
The core of the cold air will be in the Central United States. Still, even just a few days of cold air can lead to storminess and the potential for snowfall. This winter is very likely to feel different than last year, which isn’t saying much given the total lack of snowfall or cold in the Winter of 2022-2023.
In the graphic above, you can visualize the trends in expected temperature, precipitation and snowfall in NYC. Most notably, the opportunity for colder air and snowfall will increase as the winter goes on (specifically in January and February) after a relatively warmer start to the year.
It’s unclear what the potential for larger snowstorms or blizzards will look like in NYC this year. Conceptually, the pattern would argue for the possibility of one or two significant snowstorms from January into February but the details remain unclear at this extended lead time.
To recap, the expectations this winter in NYC are for:
Slightly warmer than normal temperatures
Slightly above average precipitation
Slightly above average snowfall
Finally, I wanted to take the time to say thank you to everyone who continues to support us and read our content. It is not lost on me just how special it is that so many people take the time to read what we have to say. This is our eleventh (!) year putting out a winter forecast. Thank you for being there.
John