The latest forecast update for summer 2023 shows some interesting developments. Weather in North America looks more mixed, with a strong El Niño event, while in Europe a high-pressure atmospheric blockage is the trend. When trying to understand any season and long-term forecast, we need to understand its global factors. Global weather is a very complex system with many large and small factors. Seasonal forecasts focus on large-scale pressure systems and the location of jet streams. In the Northern Hemisphere, the upcoming summer season will be a transitional period between La Niña and El Niño, which is now emerging with increasing atmospheric influence. But first, let's quickly recap the first two months of the spring season and the riders behind them. The processes that affected the first half of the spring season occurred in different parts of the atmosphere. This is because the atmosphere has many layers and our weather develops in the lowest layer of the atmosphere, called the troposphere.. But above that we have the stratosphere, which is also home to the ozone layer. Both layers have their own circulation and are connected in many different ways. The main general circulation is what we call the polar vortex. Therefore, we divide the entire Polar Vortex into an upper (stratospheric) and lower (tropospheric) part. Both fulfill their roles differently, which is why we monitor them separately. (Andrej Flis, Severe Weather Europe)