The global weather system is complex, with many large and small weather drivers. A growing El Niño event will be the main influence in the 2023/2024 Winter across the Northern Hemisphere. But there is also the infamous Polar Vortex and a new anomaly high in the Stratosphere.
The image below shows the actual pressure anomalies of the 2009/2010 Winter season. That Winter has featured a very interesting dance between the El Niño and the Polar Vortex, creating a very impressive cold Winter pattern in the process.
THE WINTER TRIO
There are always various factors and influences that shape every weather season. Some are big, but most are small. How they work together in a very fine and sensitive balance determines the final weather outcome.
Based on the latest analysis, there are three large-scale factors that we are looking at closely for the upcoming Winter season:
- El Niño event (ENSO)
- Stratospheric Polar Vortex
- Quasi-Biennial Oscillation (QBO)
Each of these factors can have different phases: warm, cold, positive, negative, east, west, and so on. So you can imagine that each year, you can have a different combination of these factors, creating a different Winter weather outcome.
We will quickly review each one and look at their role for this Winter. As you will see, they all complement each other in a very delicate balance of power.
EL NINO SOUTHERN OSCILLATION
El Niño Southern Oscillation (or ENSO) is a region of the equatorial Pacific Ocean that changes between warm and cold phases. Typically, there is a phase change around every 1-3 years.
We are currently entering a warm phase called El Niño. The cold ENSO phase is called La Niña, which was active in the past three winters.
You can see the El Niño in NOAA’s latest ocean anomaly analysis below. It stands out as an area of above-normal ocean temperatures across the equatorial Pacific Ocean. This anomaly affects the atmosphere but also tells us that the weather patterns are changing globally.
