In presenting this early winter preview or ideas we need to lay down a few ground rules. First what I am going presenting here should not in any way be considered a seasonal forecast. Making predictions about the winter in mid September is arguably the stupidest thing that anybody could do in the field of meteorology and seasonal forecasting. The only thing that is as stupid as making it winter forecast in mid- September is making a hurricane season forecast regarding possible landfalls in April …May …or …June. Tropical Cyclone activity is determined by sub seasonal patterns and greatly depend on the location of the systems development and other features such as the MJO. In a similar manner until one gets a very good idea all of the various teleconnections (jet stream patterns) as well as the sea surface temperatures…. the sun phase…. the QBO etc., it is almost impossible to make a reliable and semi-accurate winter forecast.
But there are some trends which had begun to show up which are worthy of some discussion.
The second point that I have to talk about is the issue of the change in climate. The problem here is that as soon as you mention it more than 70% of the people reading this will immediately shut down and stop thinking rationally because their politics demand allegiance to their politics/ religion/ tribe etc. It is this sort of mindset which has infected the ignorant climate denialists… the anti mask kooks and anti-vax morons in the USA (and to a lesser degree other portions of the western world).
As a scientist and as a meteorologist it does not bother me at all if my forecast goes bust or if my winter seasonal forecasts (or any seasonal forecast) is completely wrong. Shit happens. Put on your big-boy pants …shut the hell up and go on to the next thing. Figure out what you did wrong and learn from it.
Being wrong in science is not part of the conspiracy. It is not an effort to deceive you. Things change There is and always will be new data or new evidence and new discoveries.
Specifically — - there is no DIRECT correlation between a change in climate that produces a bias towards warm and or snowless Winters in the northern hemisphere. And there is no evidence of any kind that we are headed for another little ice age. Climate change has nothing to do with 1 Cold winter,1 hurricane season, or 3 wees of say Hot temperatures in October. Of course you entitled to hold on to these opinions and ideas if you want to. But the truth is that the opinions of people who are are not qualified/ educated / trained do not not matter.
For example — — I don’t care what a Hollywood star thinks about climate change or poverty.
I don’t care what a football player thinks about vaccination
I dont care what a talk show hosts thinks about the status of relationship between USA and China.
I don’t care what a rapper has to say about the history of the United States.
And I do not care if a basketball player thinks the World is Flat or that it might be flat.
WHY don’t I care? Because as a person of science I am under no obligation to listen to Stupid people.
But also…. their opinions have no education and no intelligence behind them. And here is the punch line boys and girls.
Your opinion — which of course you are entitled to — — also carries the same weight as the Hollywood star or the football player or the rapper or the NBA star.
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There is no doubt that we are headed for a La Nina this autumn and into the first portion of the winter. What IS uncertain is to what extent or what degree. The various climate models are having some difficulty in figuring out or guessing about the duration and the intensity of the upcoming La Nina. This image clearly shows that the cold water is in fact already developing along the equatorial Pacific off the coast of Peru.
And here we can look at the subscript surface cross-section of the equatorial Pacific looking into the death of about 500 meters. There is some cold water developing at the sub surface level but right now it does not appear to be particularly impressive or overwhelming.
If we take a look at the various climate models we can see that NONE of them are showing a strong La Nina event. There are a few which show a moderate event for a couple of months early in the winter but the vast majority of the climate models during the last three weeks have been depicting a WEAK La Nina event going into the winter season of 2021–2020. Even the few climate models would show a moderate La Nina event developing only show the moderate event for 2–3 months in the late autumn into the early winter. Indeed all of the climate models show the La Nina is completely over by Mid -January.
Remember that La Nina (a buildup of relatively colder than normal sea surface temperatures along the Equatorial Pacific )… El Nino (a buildup of relatively warmer-than-normal sea surface temperatures along the equatorial Pacific)…. and La Nada (which is a term used to refer to near normal sea surface temperatures along the equatorial Pacific) … are all part of the system known as ENSO. Without getting too technical…. the point that you need to understand is that La Nina and El Nino events are essentially anomalies that bring about excessive amounts of energy into the atmosphere that normally would not be there. Strong ENSO events whether it La Nina or El Nino… flood the atmosphere with unusual amounts of energy that end up dominating weather patterns regardless of the season. And strong ENSO events usually dominate the weather pattern or strongly influence it across the entire globe. On the other hand… weak La Nina or El Nino events often bring about totally different types of seasonal weather patterns.
In other words… it is a mistake to think that week La Nina or weak El Nino events are just like the strong ones only with less intensity or magnitude. They are completely different with respect to how weak ENSO events can impact the overall season/ sub seasonal weather patterns with the expected snowfall…. Temperatures… rainfall ….low-pressure tracks …the amount of cold etc.
Indeed if we look at just snowfall for weak Enso events… there are many examples where the winter has been colder than normal and or snowier the normal. BUT there are very few instances of that being the case with strong Enso events.
Let’s take a look at some data. Here these images or graphs that show seasonal snowfall for weak/ Moderate/ strong La Nina… El Ninos …and Neutral events. Notice that most of these locations do have a spike of above normal snowfall or at least normal during weak La Nina and weak El Nino events. What this means is that if you hear some TV weather guy or even a meteorologist or CPC (Climate Prediction Center) claim that weak Lanina = mild and below-normal snowfall Winters or that all La Nina events are the same …. then you know you are talking to an idiot and somebody has no clue what the hell they are talking about.
But it also makes a difference as to the location of the ENSO events. The area along the equatorial Pacific is divided up into several boxes / regions that have certain designations. This image shows you those different areas. Again without getting too technical….having a weak or moderate ENSO event with its warmest water is located in the central portions of the equatorial Pacific is generally more favorable for normal or colder than normal winter. and for either normal or above normal snowfall.
As of this writing, there is no way to know here in the middle of September where the weak La Nina will reach its maximum intensity. It could in ENSO region 1+2 which is off the coast of Peru. Or perhaps it will reach its maximum intensity in ENSO region 4 in the central Pacific Ocean. We just don’t know as of this writing.
All that being said, please keep in mind that there are several other influences besides ENSO events. The four major teleconnections in and around North America are very important in figuring out seasonal and sub seasonal trends for the upcoming winter. It is known that large pools of persistently colder-than-normal and/ or normal sea surface temperatures will support a trend for a particular type of teleconnections to develop and persist.
For example… a large pool of cold water along the West coast of North America that is persistent (aka a -PDO) will tend to support a teleconnection that is know as a “negative PNA “ pattern along the West coast of North America. The -PNA pattern features essentially a deep and fairly persistent Trough in the western third of the CONUS, and a Ridge in the jet stream across the Southeastern states. This often produces a mild and below normal snowfall pattern for the eastern third of the CONUS.
There has been some recent Improvement in figuring out seasonal trends for the AO (Arctic oscillation ) and the NAO (North American Oscillation). But this work is preliminary. Recently, a private climate weather service and analysis company that does really great work (World Climate Service) viewed the latest seasonal forecast patterns for the NAO rom the 9 big climate models based upon August 1 data. This image shows their data and projections and many of climate models are indicating a Neutral or NEGATIVE value of the NAO.
Again without getting too technical, when the NAO is either neutral or negative, it greatly increases the chances of large-scale Arctic air outbreaks coming south. It also shows a greatly increased chance of significant and/or major winter storms in the eastern CONUS (as well as in Europe). A negative NAO by definition IS a blocking pattern which means the ability of the polar jet stream to phase or merge with the southern jet stream is fairly high. This often leads to winter storms.
Conversely… a strong positive value for the NAO often favors the Plains and Midwest winter pattern and a wet / mild eastern US pattern. A positive NAO often forces the Polar jet to merge with a southern jet stream west of the Mississippi river. Indeed, this is has been the case during the last few winters in the eastern CONUS.
The image shows that several of the really good climate models such as the European, the British, the Japanese, and the German climate models are showing fairly strong negative values for the NAO in November and December, and near neutral in January. This would be a major shift from what we have seen in the past several winters. Of course, it is still early and we have to follow this data carefully over the next 60 days but it is a significant trend.
LA NINA AND THE NEGATIVE NAO
This image shows how important the other teleconnections or jet stream pattern configurations can be in a La Nina winter. The TOP row shows what the TYPICAL La Nina winter temperatures looks like for DEC (top left) JAN (top middle) and FEB ( top right). Notice that in JAN and FEB the cold shifts into the upper Plains and the western CONUS while temps are generally warmer than normal over the Deep South, which spreads into New England and the Ohio Valley by FEB.
However the middle row depict what happens when you have a La Nina event with a Negative NAO. The middle image on the LEFT show the temperature profile for DEC with a -NAO . The middle middle image is the temperature profile when you have a La Nina with a -NAO in JAN. The middle RIGHT image shows the temperature profile in FEB when you have a -NAO and La Nina. As you can see ….all three of these images or maps are significantly colder when compared to the typical December January February La Nina winter.
The bottom row again shows DEC… JAN… FEB.. but in this case the NAO phase is POSITIVE in the La Nina winter. Note hat the entire central and eastern CONUS sees a unusually warm winter.
Next we can take a look at some of the model projections for the QBO also known as the Quasi Biennial Oscillation.
WxRisk has often talked about this particular feature in the atmosphere during the autumn and winter months as is very important in helping to determine the shape of the winter. Again without getting too technical the QBO exist at the very top of the atmosphere around the equator. It oscillates back and forth from blowing in a East-West Direction for several months …then it becomes neutral and weak for a few months… and then it switches and goes back to blowing a West to East direction. The direction, the intensity, and trends of the QBO during the autumn and winter months are quite important in figuring out the overall winter pattern. If you like cold and Stormy Winters with potentially lots of snow and winter weather then you want to have the QBO in a moderately strong negative value during the winter months.
This projection from the various climate models based upon the August 1st at up shows that most of the models show a moderately strong negative QBO during the winter months. The British model and the German model are extremely strong with the negative QBO… which would actually be a inhibiting factor for the winter.
Notice here that the correlation based upon the August 1 data with the face and intensity of the QBO for November December and January is fairly strong.
Now let’s take a look at some of the climate models. The only climate model that I know of that shows any skill this far out is the European climate model (although some have maintained that the Japanese climate model has some skill out to 2 months).
These images are based upon the September 1st European climate model. And it shows some really interesting things.
DEC 2021
If correct is a very nice way to start off the winter pattern for the eastern half of the country. It shows a strong Ridge on the West coast and an exceptionally strong amount of blocking in the Arctic region (BL) which I have highlighted. More importantly, there is a strong negative anomaly in the jet stream in southeastern Canada and a rather deep Trough covering the eastern half of the country. This has the potential to be a cold and stormy month — assuming that the European climate model is getting the December 2021 jet stream pattern correct.
JAN 2022
The European climate model 500mb pattern that is IDEAL for winter storms and cold in the central and eastern CONUS. The model has strong BLOCKING pattern in northern Canada and Greenland (implying a -AO and -NAO) while at the same the subtropical Jet stream stretches front CALIF to VA. This implies waves of LOW pressure tracking in a W to E direction.
Can I get a WOOF?
FEB 2022
This is a bad-looking 500 mb pattern for anyone in the eastern third of the CONUS if you are a winter weather lover. The map shows a strongly positive NAO ( North American Oscillation) in the shape of a Greenland LOW and a correspondingly deep trough that extends southwest into south-central Canada. There is an equally strong positive anomaly or a Ridge in the jet stream in the western Atlantic Ocean which extends into the Southeastern states. This would mean a mild pattern for the eastern third of the country and only northern New England would see near normal snowfall in this kind of pattern. On the other hand, this kind of Upper air pattern is quite favorable for anybody in the Midwest or the Great Lakes region. Finally… keep in mind that this is a February projection and climate models this far out are usually worthless regardless of the model.
In summary there seems to some indication / potential for a somewhat different winter in the eastern US than what we have seen during the past few years. even if we assume that all this data is correct and that’s a big assumption we can only see into the first half of the winter at this point. By the end of the month and the beginning of October we will have a lot more data and begin to see how things are shaping up.