The 2021 2022 Winter Outlook part two

I’ve been asked to supply more teleconnection and pattern details than I did last year. So, this will go into the details more than I have, which means it will be more difficult to decipher. But I will still try to make it as clear and in as much plain speak as I can.  But the conclusion will still be in an easier to understand language.

Link to part one.  

A month ago, I released part one of the winter outlook.

So far October is shaping up close to what I outlined both in the summer outlook and part one of this outlook.

October is going to end up with temperatures on average being above average. As I said in part one, winter is going to start early. Once we get past the first 7-10 days of November; the pattern is going to change, to one that features more in the way of cold as to the warmth we’ve enjoyed for the first part of Autumn, during October.

The latest Sea Surface Temperature (SST) Anomalies (departure from average) map shows cooler temperatures stretching across the eastern into central equatorial Pacific, The cold northern Pacific, and the warm northern Atlantic.

Analogs:

Analog forecasting (pattern recognition) for something like a winter or summer forecast is very complex and subjective. The current atmospheric conditions are compared to past years with similar conditions.  These global pattern conditions involve analyzing teleconnections like the El Nino Southern Oscillation, Pacific Decadal Oscillation, Ouasi-Biennial Oscillation. This tends to be very challenging, as no two years or seasons are exactly alike. Some of the seasonal patterns carry more weight than others. The weight given is defined by individual experience and research. The more the past global weather pattern matches the current global weather pattern, the more weight it is given.  Some of the analogs can even have some of the teleconnections in different phases, when compared to the current pattern.

The analogs are 1908 - 1909, 1950-1951, 1955 – 1956, 1984-1985, 2003-04, 2005-06, 2008-09, 2013-14, 2017-18, 2018-19, and 2020-21.

1955-56 is a very strong analog. I’m also looking at years like, 1965-1966, 1988-1989, 2010,2011, and 2011-12. 1976-1977 had some similarities. It was very cold; but it was an El Nino winter. Another winter I’m looking at is the winter of 1993-1994. That winter saw persistent cold and snow across the entire Northeast into the Northern Mid Atlantic. That winter the ENSO was neutral; but it did have a stratospheric warming event similar to the one occurring now. There was a ridge off the East Coast for most of the winter. The winter of 1993-1994 came early and stayed, with most of the region seeing snow cover remain for almost a three-month period.

In part three, I will come up with a final list of analog years.

Teleconnections:

This is going to show how I’ve come to certain concussions. It is long, but if you can make it through it, it should be educational.

The El Nino Southern Oscillation (ENSO):

According to the Climate Prediction Center (CPC)…

El Nino: characterized by a positive ONI greater than or equal to +0.5ºC.

La Nina: characterized by a negative ONI less than or equal to -0.5ºC.

By historical standards, to be classified as a full-fledged El Nino or La Nina episode, these thresholds must be exceeded for a period of at least 5 consecutive overlapping 3-month seasons.

CPC considers El Nino or La Nina conditions to occur when the monthly Niño3.4 OISST departures meet or exceed +/- 0.5ºC along with consistent atmospheric features. These anomalies must also be forecasted to persist for 3 consecutive months.

Over the last few weeks, La Nina conditions have emerged; as a result, the Climate Prediction Center, has raised the La Nina Watch to an La Nina Advisory, meaning La Nina is present.

In the last week, the graphic shows that in Nino-4 the anomaly is -0.5°C, Nino region 3.4 the anomaly is around -0.8°C, Nino region 3 the anomaly is -0.7°C, but in Nino-1+2 the indices were a little warmer than last month at -0.2°C. The atmosphere is showing signs of responding to that cooler-than-average surface water.

Subsurface temperatures are also showing colder than average temperatures, in all 4 Nino regions.

The IRI/CPC plume supports the idea of a weak to moderate; that is a mixed based La Nina (somewhere between an East based and a central based). But the La Nina will still end up likely weaker than last winter. Blue bars indicate probability of La Niña, which models indicate is likely to last through this winter.

La Nina winters tend to be cooler in the northern U.S. and Canada. La Nina brings colder air down from the north and creates better conditions for chances of snow. Last year was a La Nina winter and it end up being quite snowy in many parts of Upstate New York and Northern New England.

La Nina won't be the only sea surface temperature influence on the Northeast and Mid-Atlantic this winter. Those, warmer-than-average Sea Surface Temperatures in the Atlantic Ocean will also play a role for this winter’s weather.

Sudden Stratospheric Warming (SSW):

A week or so ago, I talked about the SSW that is developing.  I compared this October to October 2010.

An SSW involves the temperatures in the upper atmosphere 50,000 to 100,000 feet above the ground. It disrupts the polar vortex in the Arctic stratosphere, and typically leads to more extreme winter weather in parts of the United States.

The polar vortex is a huge area of low-pressure spinning counter-clockwise, which rotate quickly around the Arctic Circle from west to east. When the vortex is strong, it keeps the cold arctic air bottled up north of the Arctic Circle. But when an SSW occurs, if it is a strong enough event, winds will often reverse becoming easterly and weaken. Many times, the polar vortex will split into two or three separate vortices, which then drift southward towards the mid-latitudes carrying cold air along with them.

In most cases the SSW propagates down through the clouds to the Earth's surface over the course of  20-40 days. When this happens, it throws the Arctic upper-level wind patterns off-kilter and the domino effect leads to convoluted jet stream patterns around the world in the mid-latitudes pushing the cold air out of the polar regions, into the United States and/or Europe.

The 2010 SSW was a significant stratospheric warming event; that peaked in the end of January 2010 and continuing well into March 2010. Arctic temperatures remained above the long-term mean for over two-week period. This season’s SSW is extremely early. Typically, early SSW occur in November.

 

Here is a look at our current global SST compared to 2010.  Both of them are quite similar. Interestingly, the sun too was in a similar state back in 2010 coming off a solar minimum. The stratosphere setup in 2010, that allowed for an Alaska ridge also helped disrupt the polar vortex leading to frequent waves of polar air into the US.

It is hard to say at this point what (if any) weather effects might be. But the pattern suggest we should see warming develop over Siberia, by mid-November. That means it will almost certainly result in some cold and winter weather, and given the expected pattern in the U.S., that will most likely happen along the East Coast. Time will tell how this works out.

Quasi-biennial Oscillation (QBO):

QBO is in an easterly phase: the QBO is looking to stay in an east based (colder) phase until the end of Winter 2021/2022. The QBO in the east phase, means on average, we will have a greater likelihood some SSW’s occurring during the winter. Also, on average an east based QBO is an indication for greater chances for a colder overall winter for the East Coast.  An easterly QBO can lead to a weaker jet stream which increases the chance for mid to high latitude blocking. But other teleconnections will have probably a stronger impact on weather in Northern Hemisphere.

Pacific Decadal Oscillation phase (PDO):

There is a strong correlation between the PDO and December-February temperatures across the U.S. Typically the warmer phase correlates to warmer temperatures in the southern and eastern parts of the CONUS. Of course, a positive phase has the exact opposite impact on average.

Looking at the Pacific SST, we can see they are very near Japan and much cooler south of Alaska. Meaning the PDO is currently in the negative phase. August of this year had the PDO index (PDOI) at -0. 92. Then the PDO amplified substantially in Sep 2021, with a PDOI of -1.94 Looking at the current SST in the Central and North Pacific, we find warmer than average ocean temperatures.

The East Pacific Oscillation (EPO):

The EPO tells us if there is a ridge in the jet stream into Alaska or a trough in the jet stream over Alaska.  A negative EPO features a ridge over Alaska and favors very cold weather being forced south into the central and eastern U.S.  The lead image features a trough over Alaska, shown by the blues, which favors warmth over the central and eastern United States.

The EPO is trending negative. The pattern suggests a negative EPO for November and December. Then likely trend back toward neutral for January into February.  

 

Pacific-North America pattern (PNA):

The PNA index is highly correlated with both temperature and precipitation in parts of the U.S. Here in the Northeast the correlation isn’t as strong as it would be in the Northwest. But typically, when the PNA is negative a ridge of high pressure tends to develop over the Southeast and expands northward into New England. This ridge of high pressure may become amplified this winter with the help of the well above average SSTs off the East Coast as seen in the SST chart.

On average, a positive PNA pattern is associated with an overall earlier Great Lakes ice season, while the greatest lake-effect snowfall typically occurs during a positive PNA and negative North Atlantic Osculation pattern.

The PNA is positive with September’s index value at +0.44.  The PNA will likely stay overall positive for November into the first part of January. Then it should drift back toward neutral or even turn negative for January into February.

The AO: Arctic Oscillation:

The arctic oscillation (AO): is a seesaw pattern that involves atmospheric pressure between the North Pole and the mid northern latitudes.  Typically, during the positive (warm) phase, we tend to see low pressure troughing near the pole. This normally leads to a greater likelihood of warm mild winter conditions along the East Coast. When the AO is in its negative (cool) phase. We tend to see a high-pressure ridge close to the Pole, which leads to troughing in the Middle Latitudes. During the cool phase the East Coast, normally sees cooler and stormier conditions.

The North Atlantic Oscillation (NAO):

The NAO All about where and how strong, the high- and low-pressure centers over the North Atlantic are. It deals with the fluctuation of the subtropical high in the Azores and the subpolar low near Iceland. When the NAO is positive, we have a trough of low pressure over Greenland. When the NAO is negative, we see a ridge of high pressure over Greenland. The stronger the negative phase is, the stronger the upper-level ridge over the North Atlantic and Greenland (Greenland Block) is, which improves the odds for coastal storm development of coastal storms in the Mid-Atlantic and New England. When the NAO is strongly negative NAO, cold air that has been locked up Canada, is forced south, into the northern and eastern United States. The ridging over Greenland and Iceland, tends to slow down or block storms as they move up and off the East Coast. This can lead to colder and stormier conditions over the eastern U.S.

Solar years: 

We are coming out of a deep solar minimum between solar cycles 24 and 25.

Years with similar solar cycle activity saw the southeast ridge push north, resulting in warmer overall winters.

In general, years in a solar minimum tend to have a weaker stratospheric polar vortex and are more prone to blocking.

Teleconnections interact:

Some winters, everything lines up, other winters not so much. The analog winters will each be in play from time to time. So, each of those analog winters could show up at times, leading to a lot of seasonal variability.

The current La Nina is going to likely to be weak to moderate, falling somewhere between an east based and central based. A hybrid La Nina will have a certain kind of impact.  Years that saw a hybrid La Nina, tend to see the QBO exert greater influence on the pattern than it normally does.

 

The impacts can lead to big differences in the EPO, PNA, and even NAO. But winters that had a similar QBO to what looks to be setting up for this winter tend to be colder in the east and warmer in the west.

Looking at the analogs there is a strong correlation between solar minimum, where the Atlantic was warm, the Pacific was cold, having an east based QBO, with a propensity for the AO and NAO to be overall negative. Leading to Greenland blocking.

It’s also interesting to note, that winters with a similar QBO and ENSO configuration, had a significant negative NAO at some point during the winter. Most of those winters also had at least one SSW event.

North Atlantic Osculation (NAO) and the Arctic Osculation (AO) will bring verbality to our winter Pattern. 

The PNA, AO, and NAO have a lot of interdependently between them. This symbiotic relationship. Is a big part of our wintertime temperatures and precipitation patterns. When the PNA and NAO are negative the Northeast, tends to see colder and more snowy winter weather. One of my analogs 1955-56 had a negative NAO and a strongly negative PNA. The other years with a strongly negative PNA and negative NAO were 1968-1969, 1971-1972 and 1978-1979.

Ok what does all this all this gobbledygook mean?

The warm east and southeast though can be suppressed if the North Atlantic Oscillation is negative.  The idea of still being in a low solar cycle and what looks to be a weak La Nina to start us off, would indicate the MJO going primary negative during for the last half of November and going through December.  I do think the La Nina will strengthen a bit during the winter, before weakening as we head toward spring 2022.

The current pattern is setting up to allow for a front-loaded winter for 2021 – 2022.  As I said in part one of this outlook, October temperatures, will end up being overall above average.  November is looking is looking to start out with the pattern still see-sawing back and forth. But as we get into mid and the second part of November, we’re going to see the pattern turn much more wintery. December is looking to be overall cold and stormy. 

The Pacific is cold across large parts of it. The SST in the Atlantic are quite warm with anomalies well above average. The analogs would suggest there will be a greater likelihood for Greenland ridging setting up; leading to a chance for cold outbreaks.

My research has led me to the idea that during January we will see the AO and NAO likely turn more overall positive, but flirting neutral sometimes, especially during February, which should allow for the Southwest ridge to push north; leading to more overall warmth in the Middle Atlantic and Northeast. Then the pattern likely would return to something cooler, but not as cold as it was in December.

 I’m highly hopeful about snow in the Great Lakes into much of the northern into Central New York State and New England. But even here there will be mixed events from time to time. But for those  closer to the Mid-Atlantic and along I-95 corridor will see more of a roller coaster ride. The overall pattern, means there will be opportunities for wintry weather, however, when the NAO becomes natural to positive, causing the blocking to relax, there will be mostly to all rain events.

As far as snowfall, those in the Middle Atlantic will see snow from time to time due to adjustments in the storm track as the northern jet pushes south at times.  But the idea of blockbuster snowy winter isn’t looking likely, at least right now.  Most of the analogs support the idea that those in the Great Lakes northern New York State, and northern New England, will have the best chance of seeing overall snow totals end up above average. With those across central and southern New York State and Central and southern New England seeing snowfall average to below average. Southeast Pennsylvania, and the Middle Atlantic including Baltimore and DC, will most likely end up with snow amounts ending up below average.  

This is based on how things look right now, and how they look to be trending.  but let’s see how the next 4 weeks plays out and then see how things look.

Well, that’s is it, Part three of this outlook will be released toward the end of November. Let me know what you think. Also do all y’all like the idea of more detail or like the idea of something easy to understand?