I look forward to this winter forecast every year with much anticipation, it is up there with Isotherm and Benchmark's seasonal winter outlooks.
Granted it is geared to NYC, but that really means little because you can see what is expected, and why for December, January and February.
The thing that interested me was John saying the matching analogs to this winter are very slim.
NYC Winter Forecast 2019-2020
November 11, 2019
We say it every year, but it’s worth repeating: Seasonal weather forecasting is one of the most challenging aspects of meteorology. It isn’t simply a guesstimate or an educated gamble. It is, instead, the product of months of research which typically begins at least two seasons prior. We’ve been piecing together ideas for this upcoming winter since Spring, and we are excited to present our findings to you. In that respect, we are hopeful to break down the components of the forecast in an easy to understand fashion in our NYC Winter Forecast.
Instead of focusing on individual numerical indexes and values, we are going to try to paint a picture of the atmosphere and what it will be doing over the next few months – based on several global and hemispheric oscillations, conditions, and phenomena. This will lead us to the conclusions which we believe will be the guiding forces for us during the seasons ahead.
There are three main pieces to a seasonal forecast, and while each year presents a different set of challenges, from a forecasting perspective these three pieces almost always remain engraved in the process. We must look at current conditions, analog years, and forecast guidance for the upcoming months to begin our forecast.
The Summer of 2019 was characterized by a significant change in the higher latitudes of the atmosphere. From the arctic regions of the Pacific to the arctic regions of the Atlantic, large ridging became established. This degree of high latitude blocking is highly anomalous, especially when averaged out over a 3 monthly period.
Most notably, perhaps, is the fact that this high latitude blocking also had not been observed in quite some time, especially over such a long duration. This summer, we recorded one of the longest -NAO periods on record.
Such a change in the high latitudes certainly needs to be factored in to the Winter Forecast and we perused all of the available data to weight and rationalize our forecast properly.
The role of ENSO in the upcoming Winter 2019-2020
Anticipated ENSO Conditions: Neutral to Weak El Nino
ENSO conditions are one of they key drives to the Winter pattern. “Tropical forcing” 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 convection, which then accordingly results in atmospheric ridging, and subsequently moves downstream, balancing the atmospheric regime. In a general sense, the more anomalous the positive sea surface temperature anomalies, the more convection that can then exert a stronger forcing mechanism on the adjacent regions of the atmosphere, reverberating throughout the globe.
We anticipate weak-neutral to weak El Nino conditions during this Winter 2019-2020. These conditions were factored in to our Winter Forecast and our analogs were weighted and sorted accordingly. It is important to note that there is a great deal of variability among analogs as a result of the weak ENSO signal this year.
The El-Nino that develops over the next few months may be of the Central Based nature – with the majority of the warming taking place in Central regions of the tropical Pacific. It is important to note that this is different from a “Modoki” El Nino – which by definition also features some cooling in the Eastern Tropical Pacific Ocean.
Central Based El Nino events have a very different subset of effects when compared to basin-wide or especially Eastern Based El Nino Events. In general, they are cooler across the country in comparison, but particularly in the Eastern United States. There are still a few weeks to go before we will know with greater certainty how the ENSO conditions will evolve. Close monitoring of both the current conditions, subsurface warming and depth will be critical.T
The Quasi-Biennial Oscillation (QBO) this winter
Prediction: Descending easterly -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 QBO often supports higher latitude blocking and ridging, while a more positive QBO supports some resistance to high latitude blocking in those areas.
Recently, a negative (easterly) QBO has been descending toward 30mb. This is an important factor in the Winter ahead, but it is uncertain how quickly the easterly QBO will continue to descend. We used a split analog package as there are only a limited number of QBO analogs which compare to the evolution so far this year.
Other Factors (PDO, Solar Activity, etc)
There are many other factors that go in to producing a Winter Forecast. We try to weight and balance our forecasts based on a variety of subjects. For example, this year the PDO (Pacific Decadal Oscillation) is at -0.66, but is displaying some characteristics more typical of a +PDO. We must weight our analogs accordingly.
Solar activity is at a near 10-year minimum this year, which certainly will be factored in to the forecast as well. But all of these things tie back to the proper weighting of analogs to get an idea of exactly how the atmosphere is behaving.
Analog years are an important component to winter forecast development. Looking back to past years that featured similar atmospheric progressions and conditions can offer us a peak 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 usage of analog years 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? The answer lies in forecaster preference, and as is the case with most things, how a forecaster weights and blends different components into the forecast will have a huge impact on the end result.
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. 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 are comfortable with our analog composites that were presented and have factored them into our forecast as we typically do – simply a piece of the larger forecasting 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 months temperature and anticipated precipitation trends. While precipitation maps are not included (lower confidence) we discuss precipitation pattern and potential within each individual months breakdown. Please keep in mind, this is a NYC Winter Forecast, but we do discuss national trends and weather patterns as well!
December 2019 is expected to feature an expansive Southeast Ridge with warmer than normal temperatures across much of the Southeast United States. Warmth should also spread northward into the Mid-Atlantic States at times, as well as into New England.
The majority of cold risks will be centered in the Northern Plains, where occasional cold shots are likely. It remains to be seen exactly how impressive these cold shots will be, and uncertainty is rather high – precluding any more impressive temperature anomaly forecasts there.
The main area of uncertainty is over New England. The development of a -NAO by mid to late month could favor some colder temperatures in those regions, which may ultimately adjust the monthly average composites. However, we do not expect December to be an overly wintry month in the Northeast states at all.
Winter is expected to evolve more dramatically during the month of January, with the potential for further episodes of high latitude blocking on both the Pacific and Atlantic sides of the arctic. This should dislodge cold air southward into Canada and the United States.
Below normal temperatures are expected on the monthly composites across the Northern Plains and parts of the Ohio Valley and Northeast. Periodic expansion of the Southeast Ridge should keep parts of that area above normal with temperatures even on a monthly basis.
Snowfall is expected to average near or slightly above normal in the Midwest, Great Lakes and Northeast during January – which will feel active compared to the slow start in December.
As you may expect at this juncture, confidence is lowest in regards to February when compared to any other month. With that being said, our forecast carries forward the expectation that high latitude blocking will continue to remain prevalent during this month. Colder than normal temperatures are expected across the Great Lakes and Northeast as a result.
Snowfall should again average near or slightly above normal in parts of the Great Lakes, Ohio Valley and Northeast, with a specific emphasis on New England where snowfall may end up solidly above average.
Much of the Western USA is expected to be warm during this month as ridging remains stout.
NYC Winter Forecast 2019-2020 Highlights and Summary
We expect Winter 2019-2020 to start rather slowly, although there is a window for some wintry weather in very early December. The month will largely be characterized by bouts of warmth along the East Coast. The greatest potential for winter weather during December will exist across the Plains and Midwest.
Gradually, as we move through January, Winter will pick up steam with a colder and snowier pattern becoming established. This may continue into February.
Our current expectation is for temperatures to average near or slightly above average in NYC, with near or slightly above average snowfall. The worst of the Winter will likely be observed from mid to late January into early February.
We wanted to take the time to thank you for reading our 2019-2020 Winter Forecast. The forecast was compiled at Empire Weather, LLC and New York Metro Weather, LLC in Fanwood, New Jersey from May of 2019 through October of 2019. The graphics were compiled by John Homenuk. Analog work and composition was completed by John Homenuk, Ed Vallee, Doug Simonian and Miguel Pierre. The presentation was compiled and edited by John Homenuk, Ed Vallee and Doug Simonian. Additional forecast feedback, commentary and production was provided by Steve Copertino.
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 deliver a forecast that provides detail, information and clarity.
Here’s to a wonderful Winter ahead! PS – Don’t forget to check our daily forecast page here.
John founded New York Metro Weather in 2008, and the website officially became an established LLC in 2012. Since completing his meteorology studies at Kean University, John has worked on both New York Metro Weather and Empire Weather to provide detailed and personalized weather forecast to the public and private sector.