The 2023 spring season is approaching, with forecasts showing that the pattern of jet streams over the North Pacific and Atlantic will be influenced by the waning of La Niña. A high pressure system in the Pacific will define weather patterns in North America, with a possible stratospheric warming event playing a role early in the season.
The cold oceanic phase in the equatorial Pacific is already breaking. It is expected to decrease rapidly in early spring.
But despite the collapse of these cold ocean anomalies (La Niña), their influence may still linger on the global climate circulation. Long-term climate calculations also show this, extending the La Niña jet flow pattern from winter to spring 2023.
WINTER SEASON IN PROGRESS
The winter weather station covers the period December-January-February. The first two months are over, so we have now entered the last month of the winter weather season.
Below is the analysis of temperature anomalies for the United States and southern Canada. The period includes December and January. You can see above normal temperatures all over continental Europe. However, above normal temperatures prevailed in the eastern half of the United States and Canada.
This, of course, does not mean that the weather was warmer than usual all the time. We all remember the record cold air surge in the United States in December. But, most of the time, the temperatures were above normal, which prevails in the final average frame.
Below we have the same average from December to January, but due to pressure anomalies. A strong pattern of lockdown dominated the northeastern United States, eastern Canada, and southern Greenland. At the same time, an area of high pressure can be seen in the North Pacific related to La Niña and general high pressure in the Arctic region.
A low pressure system was present in the western United States, bringing heavy rainfall to California. However, it was situated further south than normal for a La Niña winter due to the strong blocking of high pressure over Canada and Greenland.
Looking at the snow analysis below, we can see areas with more or less snow than normal. This shows a more typical La Niña pattern, with more snowfall in the western and northern United States. The total snowfall anomaly for the season is 91%, below the long-term average (100%).
LAST MONTH OF WINTER
Let's quickly review the latest forecast for the last month of winter. By February, a strong high pressure system in the North Pacific is forecast to be the primary driver of the North American weather regime. In response, low pressure remains over Canada, diverting the jet stream down over the northwestern United States and east into Canada.
A wide area of low pressure can also be seen over Greenland and the North Atlantic. This allows a strong high pressure system to advance over Europe.
Looking at the surface temperature probability forecast for Europe, we see a warmer pattern. Most of the continent is in the warmer temperature range. However, average temperatures are more likely in the western/southwestern parts as the month begins with cooler than normal weather.
In North America, the latest monthly forecast for February shows cooler surface temperatures over most of western Canada and the western United States. Warmer than normal temperatures are forecast for the eastern half of the United States, with stronger warmer anomalies in the Southeast.
This looks much more like a typical La Niña pattern, with cooler air more concentrated in the northwestern United States and parts of the west.
NOAA's official outlook also shows a similar forecast for February in the United States. Once again, below-normal temperatures are concentrated in the northern and northwestern United States. But in the southeast and east, we can see temperatures above normal.
The precipitation forecast shows more precipitation in the northern half of the United States. This also means more snowfall in parts of the Northwest and Upper Midwest. The deep south of the United States is expected to be drier than normal.
But what is driving these winter patterns, and how will it affect spring in 2023?
OCEAN AND SEASONAL CLIMATE
One of the main large-scale drivers of this cold weather season is the La Niña event in the tropical Pacific Ocean.
In the image below, you can see the latest ocean temperature anomaly in the Pacific. Be aware of the cooler-than-normal surface waters in the tropical regions of the Pacific. This is a La Niña event, which spans the length of the equatorial Pacific Ocean, driven by the trade winds.
The presence of a cold Niña has been the main characteristic in the development of the weather since late autumn and will continue until spring.
La Niña is just a different name for the low temperatures of the tropical Pacific Ocean. The current ocean-atmosphere system is called ENSO (El Niño Southern Oscillation). This region in the tropical Pacific Ocean alternates between cold and warm phases.
In the image belowNOAA Weather, you can see a typical circulation pattern during a cold ENSO event in the ocean. Air sinks into the eastern Pacific, creating stable, high-pressure weather conditions. Conversely, air rises in the western Pacific, causing lower pressure, frequent storms, and heavy rain in the western Pacific.
In this way, ENSO significantly impacts tropical convection patterns and the ocean-atmosphere system. Through this delicate feedback system, it distributes its climatic influence globally.
To better understand the development of ENSO, we produced a video showing ocean temperature anomalies from summer to fall 2022.
ENSO cooling resumed in August when cold waves developed in the equatorial Pacific. But it intensified further in September, when the easterly trade winds became stronger.
Historically, a strong blockage of the high pressure system in the North Pacific is the most typical effect of a cold phase of ENSO. In addition, a strong high pressure system in the North Pacific aids the development of a low pressure region over Alaska and western Canada.
These effects generally translate well to early spring. Therefore, we generally see the continued presence of the high pressure system in the North Pacific even after winter.
In the image below, you can see the average position of the jet stream during La Niña winters. Plus, you can see the resulting weather patterns across the United States and Canada as the polar jet stream takes a different path.
The shifting jet stream brings cooler temperatures and storms to the northern and northwestern United States. But it generally creates hotter, drier weather in the southern and eastern states.
In this way, the jet stream can divide the United States into two climatic poles. In the northern part of the country, cooler and wetter events are more frequent as the jet stream drives storm systems and cold weather there.
ENSO SPRING FORECAST
The analysis and forecast set below the ECMWF shows the forecast for the eastern ENSO region. La Niña conditions (below -0.5) will weaken rapidly as winter ends. But atmospheric effects can persist for some time, even as ocean anomalies slowly fade.
Looking at the ocean anomaly forecast map, we can see that the ECMWF predicts warm anomalies emerging in the equatorial Pacific. This indicates that a warm phase, also known as El Niño, is likely to begin to develop.
The forecast map above does not show proper El Niño conditions, but does show anomalies emerging from the warm ocean. A proper El Niño is likely to emerge during the summer or early fall and affect the upcoming 2023/2024 winter season according to the latest forecasts.
But what climate development do the latest long-term forecasts for spring show?
SPRING 2023 - SEASONAL FORECAST
We focus on the two main (or most widely used) seasonal models for this forecast: the European ECMWF and the US CFSv2. The charts are fromECMWFIt's inCPC/NCEP.
All of these forecasts show an average image over three spring months (March-April-May) and show prevailing weather patterns.
Even if the models were completely accurate, it does not mean that such weather conditions would last for three months straight. Rather, it just suggests what the prevailing weather patterns would look like throughout the season.
ECMWF SPRING SEASON FORECAST
The ECMWF pressure pattern forecast below shows the typical La Niña high pressure system in the North Pacific. The low pressure system is indicated in western Canada, with another area of high pressure in Greenland. The above segment shows that the jet stream bends between high and low pressure systems.
We also see the North Atlantic in a negative westNorth Atlantic Oscillation (NAO)Mode and blockade over the North Atlantic. The model suggests a possible area of low pressure over southwestern Europe in such a configuration.
The global air mass temperature forecast below shows North America divided into two parts. First, western Canada is forecast to be colder than usual. Thanks to the jet stream, there is a high probability that cooler air will spread southward, into the northern United States, over the Midwest, and partly into the northeastern United States.
Europe also has above normal temperatures in the east. But we don't see strong positive anomalies in the west due to the high pressure system over Greenland.
Taking a closer look at Europa, you can see that the surface temperatures are above normal. As a result, warmer temperature anomalies and milder conditions are more likely in the eastern parts. The central and western regions are likely to see occasional cold fronts from the north/northwest as Greenland allows more northerly flow.
In North America, the ECMWF forecast suggests normal to cooler-than-normal surface temperatures in the northwestern United States and the upper Midwest. Additionally, we see an indication of cooler-than-normal air encroaching on the Northeast as well.
Despite being warmer than normal, the central parts of the United States tend to see occasional cooler weather and early spring snowfall during these jet stream patterns. But most of the warmer-than-normal temperatures are forecast in the Deep South and Southwestern United States.
In terms of precipitation, Europe tends to have more precipitation in the central and south-central regions. This probably indicates that the model is heading towards an area of low pressure in western and southwestern Europe. More precipitation is also indicated in areas further north.
The North American precipitation anomaly predicted below shows a more normal La Niña pattern in Canada and the United States. As a result, the United States has wetter conditions in the Northwest and East and drier conditions in the Southwest.
Combined with cooler temperatures, this also affects the potential for early spring snowfall.
SNOW FORECAST FOR EARLY SPRING
Although spring is generally referred to as the beginning of the warmest part of the year, it still offers snowfall events, especially in early March. But looking at the March snow forecast image below, you can see that most of Europe has below-normal snowfall in early spring, except in the alpine regions.
In early spring in North America, you may see more snow than usual, covering a large area from western Canada to the northwestern United States and the far Midwest. Surprisingly, the forecast also shows an increase in snowfall potential in the southeastern United States.
We will produce an article with a more detailed analysis of the spring snowfall potential.
CFS SPRING SEASON FORECAST
Unlike the European model, we tend to use the main North American long-range model, theCFS version 2from NOAA/NCEP in the United States.
The CFS model agrees with the ECMWF Over the North Pacific, predicting a high pressure system. No low pressure anomaly is drawn, but in such a pattern, we know one can be expected over Canada.
But it differs over the North Atlantic, with indications of a low pressure system over the region. This creates a different weather pattern in Europe, which must be under a wide area of high pressure.
Air mass temperatures over North America do not show actual cold anomalies, but in the case of this model's prediction, this area would be over Canada and the northern United States. As expected, Europe is hotter than normal, with high pressure over the continent.
Taking a closer look at Europe, surface temperatures are warmer than normal across much of the continent, especially in the northern and central regions. That's not too far off from the ECMWF, but it doesn't allow for as many persistent cold spells in the spring.
The North American forecast below shows a more La Niña-like temperature pattern. However, the coldest temperatures remain in western Canada and extend into the northwestern United States and the Midwest. There is no indication of cold anomalies, but this is likely due to model and climatology bias. In reality, there are always areas of warmer and colder than normal weather.
Warmer than normal weather prevails in the southern parts of the United States. A gap in the warm anomaly indicates a probable path of spring cold over the Midwest into the northeastern United States, similar to the ECMWF.
Looking at the precipitation forecast, we see normal to drier conditions across Europe. This was mainly expected given the high pressure prediction of this model.
In North America, the precipitation forecast calls for drier-than-normal conditions in the southwestern United States and along the West Coast. The northern and eastern United States are likely to experience more precipitation than normal due to the waning influence of La Niña.
SPRING OUTLOOK - SUMMARY
Because reading images and descriptions can be confusing at times, we've put together the overall summary of the Spring 2023 forecast:
Europait is expected to have warmer than average temperatures across much of the continent. This, however, does not mean that there will not be cold fronts and colder days. The ECMWF, for example, shows a locked Greenland pattern. This increases the chances of a northern flow into continental Europe.
The models do not conform to the standard over the North Atlantic. The main difference is the pressure anomaly over Iceland/Greenland. The ECMWF enters the Greenland lock, while the CFS is closer to a low pressure anomaly.
Depending on the model chosen, the precipitation forecast shows mostly normal conditions. But a lot depends on the pattern of the North Atlantic and the possibility of a more local area of low pressure over southwestern Europe.
The North American Spring Forecastlooks solid for a typical extension of the La Niña winter pattern. Most of western and central Canada should expect colder and snowier conditions, along with parts of the northern United States.
The northwestern United States is expected to experience normal to cooler spring weather with increased precipitation. This increases the chance of spring snowfall in the Northwest. More snowfall is also forecast in early spring in the upper Midwest.
The southern United States has a high chance of warmer and drier than normal weather in the spring. This, however, does not mean that no cold front can hit the southern states. Rather, it implies that frequent southward cold fronts are much less likely to occur in a La Niña pattern.
The main channel of cold air surges in the spring appears to be from the northwestern United States and the Midwest to the central and eastern United States. Despite the forecast for warmer temperatures for the central and eastern United States, a surge of cold air may be masked by the warmer seasonal average.
NOAA OFFICIAL SPRING OUTLOOK
Below is the official spring temperature forecast for the United States by NOAA. Shows the temperature probability, with equal colder probabilities in the northern United States. The southern half of the country and the Northeast are more likely to have warmer-than-normal weather, as seen in previous models.
The official precipitation forecast is also quite similar to the model forecast. We see an equal or greater chance of more precipitation in the eastern United States throughout the Ohio Valley. On the other hand, the southwestern United States is forecast to have a drier than normal spring.
But there is one event that can significantly affect spring weather patterns.
STRATOSPHERIC POLAR VORTEX COLLAPSE
Below is the pressure and temperature forecast for the stratosphere in mid-February. You can see a strong wave of stratospheric warming moving across the polar regions. The Polar Vortex moves away from the North Pole and weakens strongly, with an inverted circulation.
This means that the stratospheric circulation is breaking up, shifting the influence of the stratosphere down into the lower levels.
By looking at the vertical pressure anomalies below, you can see the scheduled forecast for the first half of February. Again, it shows high-pressure anomalies in the stratosphere, associated with strong warming anomalies.
It is not known exactly how this will happen and how strong the stratospheric warming will be. But based on early indications, we are likely dealing with a proper collapse of the stratospheric circulation that could influence the weather in early spring.
We'll keep you posted on developing weather trends in the coming seasons, so bookmark our page. Also, if you saw this article on the Google App (Discover) feed, please click the Like (♥) button to see more of ourpredictionsand our latest articles ontime and naturein general.
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