NYC Winter Forecast 2021-2022 | Colder and active start, warmer finish

The Winter of 2021-2022 is likely to begin with a colder and more wintry pattern than normal in NYC. The second half of the winter, however, is expected to be warmer and less snowy than normal. NYC’s 30 year average annual snowfall is 28.9″, and we expect slightly above normal snowfall this season.

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We say it every year, but it is worth repeating: Seasonal weather forecasting is one of the most challenging aspects of meteorology. It is the product of several months of intensive research, which often begins in the prior Spring. We have been piecing together ideas for this upcoming winter since then, and we are excited to finally have a finished product. 

Instead of focusing on individual numerical indexes and values, we are going to try to 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.

The role of ENSO

Anticipated ENSO Conditions: Moderate or strong La Nina

The El Niñdo-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 weak La Nina conditions during the upcoming winter. La Nina conditions are observed when colder than normal temperature anomalies exist in the aforementioned tropical regions of the Pacific Ocean. 

La Nina events can be broken down into subcategories separate from their strength, based on location. The most frequently observed types of La Ninas are “central based”, when the coldest anomalies are in the central Tropical Pacific and “east based”, when the coldest anomalies lean eastward, closer to Central and South America in the eastern tropical Pacific. This year, colder than normal sea surface temperatures extend across both the Central and Eastern ENSO regions, with a slight lean towards the eastern regions closer to South America.

Using a weighted analog set featuring a lean towards eastern-based La Nina events of at least moderate strength, we are able to compile an analog set of the SST anomalies in the Tropical Pacific. This analog set matches quite closely with ongoing and expected conditions. 

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 descending QBO

The QBO is a very important atmospheric index which monitors the quasi periodic oscillation between the equatorial zonal wind – from easterlies to westerlies. A negative (easterly) QBO often supports higher latitude blocking and ridging, while a more positive (westerly) QBO supports some resistance to high latitude blocking in those areas.

Recently, an easterly QBO has been observed. This is an important factor in the Winter ahead, especially given the understanding that La Nina events tend to feature Southeast US ridging overall. Think of it this way – if ridging is favored by tropical forcing, this propensity for high latitude blocking to develop could act to mitigate it.

With an easterly QBO in place, there is a greater likelihood of high latitude blocking – and we will have to closely monitor the stratospheric polar vortex to see how the higher latitudes might behave.

The North Atlantic Oscillation (NAO) 

Prediction: Neutral to Negative (-) NAO on average

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 negative NAO is associated with colder, more active conditions in NYC during the winter months. A positive NAO is correlated with warmer conditions overall. This year, we are expecting the NAO to average near neutral, but negative during the first half of the winter and more positive during the second half of the winter.

Other Factors & Analog Years

Analog years are an important component of winter forecast development. Looking back to past years that featured similar atmospheric progressions and conditions can offer us a peek into how things may evolve in the winter ahead. We can appropriately weight these based on our understanding of the atmosphere during those years and how it compares to current conditions.

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 variable La Nina state with moderate to strong intensity and also fit the pattern across the rest of 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 2021

The month of December is once again expected to offer the most wintry intrigue of the season in the Northeast United States. High latitude blocking appears likely to develop as a result of a weaker than normal stratospheric polar vortex and easterly QBO.

In simple terms, we expect colder air which normally resides in the Arctic and Canada to be dislodged southward into parts of the United States. The core of this should remain over the Great Lakes, but colder than normal temperatures can also be expected across the Northeast.

The potential for wintry weather should exist especially during the first half of the month. This may initially begin the interior and higher elevations, but the potential for early season snow is also anticipated in the NYC Metro.

January 2022

January is expected to be a month that is largely defined by volatility. While the first half of the month could be colder and remain active, a mid month transition is anticipated. High latitude blocking is expected to oscillate, leading to periods of warmth followed by shots of cold, but no real sustainability to thee pattern. A larger mid month storm could signal a change to the pattern overall.

The second half of the month is expected to trend warmer across the Southern and Eastern parts of the country, with that warmth eventually working into the NYC Metro Area as well.

February 2022

It is relatively rare to have relative agreement among a series of analogs. While all of our analogs feature slightly different hemispheric conditions, there is one thing that they all agree upon: A Southeast Ridge will expand in February.

High latitude blocking is expected to retreat during this time period, with a positive NAO and amplified Pacific patter. This will help facilitate troughing in Western North America, and result in ridging in the Eastern US. Warmer than normal temperatures are likely in the Eastern US as a result.

While February has been active during the past few winters, we expect this one to be relatively quiet in regards to wintry weather. Warmer than normal temperatures are expected in NYC as well.

NYC Winter Forecast 2021-2022 Highlights

Temperatures: Slightly warmer than normal (0 to +2)

Precipitation: Wetter than normal

Snowfall: Slightly above normal (27-33″)

Winter 2021-2022 is expected to be off to a fast start, with colder than normal and more wintry than normal conditions in the NYC Metro during December. After a transitional month in January, warmer and less wintry than normal conditions are anticipated in February. While temperatures will average slightly above normal, we do anticipate snowfall to average slightly above normal as well.

We wanted to take the time to thank you for reading our Winter Forecast. It is not lost on us how special it is that so many folks take the time to read what we have to say. Each year, we are fortunate enough to produce and release a Winter Forecast both to clientele and to the public. We are grateful for the opportunity to share our forecast with as many people as we can, and we hope to have delivered a forecast that provides detail, information and clarity.

The forecast was compiled at Empire Weather, LLC and New York Metro Weather, LLC in Fanwood, New Jersey from May of 2021 through November of 2021. The graphics were compiled by John Homenuk. Analog work and composition was completed by John Homenuk, Ed Vallee, Doug Simonian and Steve Copertino.

Cheers to a wonderful Winter ahead!